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1998 Microchip Technology Inc. December 1998 /DS51115E
microID™ 125 kHz RFID
System Design Guide
INCLUDES:
• Passive RFID Basics Application Note
• MCRF200 Data Sheet
• MCRF250 Data Sheet
• Contact Programming Support
• RFID Coil Design
• FSK Reader Reference Design
• PSK Reader Reference Design
• ASK Reader Reference Design
• FSK Anti-Collision Reader Reference Design
• Using the microID Programmer
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December 1998 /DS51115E 1998 Microchip Technology Inc.
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1998 Microchip Technology Inc. December 1998 /DS51115E
DATA SHEET MARKINGS
Microc hip uses v arious d ata sheet m arking s to design ate each do cument pha se as it re lates to the product dev elopme nt
stage. The markings appear at the bottom of the data sheet, between the copyright and document and page numbers.
The definitions for each marking are provided below for your use.
“All rights reser ved. Copyright © 1998, Microchip Technology
Incorporated, USA. Information contained in this publication
regarding devi ce applications and the like is intended through
suggestion only and may be superseded by updates. No rep-
resentation or warranty is given and no liability is assumed by
Microchip Technology Incorporated with respect to the accu-
racy or use of such inform ation, or infringement of patents or
other intellectual property rights ar ising from suc h use or oth-
erwise. Use of Microchip’s products as cr itical com ponents in
life support systems is not authorized except with express
written approval by Microchip. No licenses are conveyed,
implicitly or otherwise, under any intellectual property rights.
The Microchip logo and name are registered trademarks of
Microchip Technology Inc. in the U.S.A. and other countries.
All rights reserved. All other trademarks mentioned herein are
the property of their respective companies. No licenses are
conveyed, implicitly or otherwise, under any intellectual prop-
erty rights.”
Trademarks
The Microchip name, logo, KEELOQ, and PICmicro are
registered rademarks of Microchip Technology Incorporated in
the U.S.A.
microID and RFLAB are a trademarks of Microchip
Technology Inc.
All other trademarks mentioned herein are property of their
respective companies.
Marking Description
Advance Information The infor mation is on products in the design phase. Your designs should not be
finalized with this information as revised infor mation will be published when the
product becomes available.
Preliminary This is preliminary information on new products in production but not yet fully
char acterized. The specific ations in t hese data s heets ar e subject to c hange wit h-
out notic e. Be fore y ou fin alize y our desi gn, ple ase ensure that y ou ha ve the most
current revision of the data sheet by contacting your Microchip sales office.
No Marking Information contained in the data sheet is on products in full production.
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December 1998 /DS51115E 1998 Microchip Technology Inc.
1998 Microchip Technology Inc. DS51115E-page v
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PAGE
AN680 PASSIVE RFID BASICS
Introduction ........................................................................................................................................ 1
Definitions ..........................................................................................................................................1
Reader ........................................................................................................................................1
Tag ............................................................................................................................................. 1
Carrier ........................................................................................................................................1
Modulation ..................................................................................................................................1
System Handshake ...........................................................................................................................2
Backscatter Modulation .....................................................................................................................2
Data Encoding ...................................................................................................................................3
Data Modulation ................................................................................................................................4
Anticollision .......................................................................................................................................5
MCRF200 DATA SHEET
Features ............................................................................................................................................ 7
Application .........................................................................................................................................7
Package Type ...................................................................................................................................7
Description ........................................................................................................................................7
Block Diagram ................................................................................................................................... 7
1.0 Electrical Characteristics ............................................................................................................8
1.1 Maximum Ratings ................................................................................................................8
2.0 Functional Description ................................................................................................................ 9
2.1 Rectifier – AC Clamp ...........................................................................................................9
2.2 Coil Load Modulation ...........................................................................................................9
2.3 VDD Regulator .....................................................................................................................9
2.4 VPP Regulator .....................................................................................................................9
2.5 Clock Generator ........................................................ ..........................................................9
2.6 IRQ Detector ...................... ............................................................. ............................ ...... ..9
2.7 Power-On Reset ..................................................................................................................9
2.8 Modulation Lo gic .................................................................................................................9
3.0 Configuration Logic Control Bit Register ..................................................................................10
3.1 Organization ......................................................................................................................10
3.2 Baud Rate Timing ..............................................................................................................10
3.3 Column and Row Decoder Logic and Bit Counter .............................................................10
4.0 Modes of Operation ..................................................................................................................12
4.1 Native Mode ............................................. .............................................................. ..... ......12
4.2 Read Mode ........................................................................................................................12
microID™ Design Guide Product Identification System ..................................................................13
Table of Contents
DS51115E-page vi 1998 Microchip Technology Inc.
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PAGE
MCRF250 DATA SHEET
Features .......................................................................................................................................... 15
Description ......................................................................................................................................15
Application .......................................................................................................................................15
Block Diagram ................................................................................................................................. 15
1.0 Electrical characteristics ...........................................................................................................16
1.1 Maximum Ratings ..............................................................................................................16
2.0 Functional Description ..............................................................................................................17
2.1 Rectifier – AC Clamp ......................................................................................................... 17
2.2 Coil Load Modulation .........................................................................................................17
2.3 VDD Regulator ................................................................................................................... 17
2.4 VPP Regulator ................................................................................................................... 17
2.5 Clock Generator ........................................................ ........................................................17
2.6 IRQ Detector ...................... ............................................................. ............................ ......17
2.7 Power On Reset ......................................................................... .......................................17
2.8 Modulation Lo gic ...............................................................................................................17
3.0 ConfigurationLogic ...................................................................................................................18
3.1 Contro l Bit Register ...........................................................................................................18
3.2 Organization ......................................................................................................................18
3.3 Baud Rate Timing ..............................................................................................................18
3.4 Column and Row Decoder Logic and Bit Counter .............................................................18
4.0 Modes of operation ...................................................................................................................20
4.1 Native Mode ............................................. .............................................................. ..... ......20
4.2 Read Mode ........................................................................................................................20
5.0 Anticollision ..............................................................................................................................21
MCRF250 Product Identification System ........................................................................................22
TB023 CONTACT PROGRAMMING SUPPORT
Introduction ......................................................................................................................................23
Definitions ........................................................................................................................................23
File Specification .............................................................................................................................23
Table of Contents (Continued)
1998 Microchip Technology Inc. DS51115E-page vii
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PAGE
AN678 RFID COIL DESIGN
Introduction ......................................................................................................................................25
Review of a Basic Theory for Antenna Coil Design .........................................................................25
Current and Magnetic Fields ....................................................................................................25
Induced Voltage in Antenna Coil .....................................................................................................27
Wire Types and Ohmic Losses .......................................................................................................30
Wire Size and DC Resistance ..................................................................................................30
AC Resistance of Wire .............................................................................................................30
Inductance of Various Antenna Coils .............................................................................................. 32
Inductance of a Straight Wire ...................................................................................................32
Inductance of a Single Layer Coil .............................................................................................32
Inductance of a Circular Loop Antenna Coil with Multilayer .....................................................33
Inductance of a Square Loop Coil with Multilayer ....................................................................33
Configuration of Antenna Coils ........................................................................................................34
Tag Antenna Coil ................. ...... ..... .................................. .................................. ......................34
Reader Antenna Coil ................................................................................................................35
Resonance Circuits, Quality Factor Q, and Bandwidth ...................... .................................. ........... 36
Parallel Resonant Circuit ..........................................................................................................36
Series Resonant Circuit ............................................................................................................37
Q and Bandwidth ......................................................................................................................39
Limitation on Q .........................................................................................................................39
Tuning Me thod .............. ...... .............................................................. ................................. ......40
FSK READER REFERENCE DESIGN
Read Range of RFID Devices ......................................................................................................... 41
References ......................................................................................................................................42
1.0 Introduction ...............................................................................................................................43
2.0 Reader Circuits .........................................................................................................................43
2.1 Transmitting Section .......................................................................................................... 44
2.2 Receiving Section ..............................................................................................................44
3.0 microID™ FSK Reader ............................................................................................................45
4.0 FSK Reader Schematic ............................................................................................................46
5.0 FSK Reader Bill of Materials ....................................................................................................47
6.0 FSK Source Code for the PICmicro® MCU ..............................................................................49
PSK READER REFERENCE DESIGN
1.0 Introduction ...............................................................................................................................59
2.0 Reader Circuits .........................................................................................................................59
2.1 Transmitting Section .......................................................................................................... 60
2.2 Receiving Section ..............................................................................................................60
3.0 microID™ PSK Reader ............................................................................................................61
4.0 PSK Reader Schematic ............................................................................................................63
5.0 PSK Reader Bill of Materials ....................................................................................................64
6.0 PSK Source Code for the PICmicro® MCU .............................................................................. 67
Table of Contents
DS51115E-page viii 1998 Microchip Technology Inc.
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PAGE
ASK READER REFEREN C E DESIGN
1.0 Introduction ...............................................................................................................................77
2.0 Reader Circuits .........................................................................................................................77
2.1 Transmitting Section .......................................................................................................... 78
2.2 Receiving Section ..............................................................................................................78
3.0 microID™ ASK Reader ............................................................................................................79
4.0 ASK Reader Schematic ............................................................................................................80
5.0 ASK Reader Bill of Materials ....................................................................................................81
6.0 ASK Reader Source Code for the PICmicro® MCU .................................................................83
FSK ANTICOLLISION READER REFERENCE DESIGN
1.0 Introduction ...............................................................................................................................99
2.0 Reader Circuits .......................................................................................................................100
3.0 AntiCollision Reader Schematic .............................................................................................102
4.0 Anticollision Reader Bill of Materials ...................................................................................... 103
5.0 FSK Anticollision Source Code for the PICmicro® MCU ........................................................105
USING THE microID™ PROGRAMMER
1.0 Introduction .............................................................................................................................117
2.0 Programming Signal Waveform ............................................................................................. 118
2.1 Power-up, Gap, and Verifica tio n Signa ls ......................................... ................................118
2.2 Programming Sequence ..................................................................................................118
3.0 Calibration of Programming Voltage ......................................................................................1 20
4.0 Programming Procedure ........................................................................................................121
4.1 Error Conditions ..............................................................................................................121
5.0 Programming in a Standard Terminal Mode ..........................................................................123
5.1 Programmer Wake-up .....................................................................................................123
5.2 Blank Check ............................ .................................. ......................................................123
5.3 Program and Verify the Device ................ .............................................................. ......... 123
5.4 Error Conditions ..............................................................................................................123
6.0 microID™ Programmer Schematic .......................................................................................126
7.0 microID™ Programmer Bill of Materials .................................................................................127
8.0 Programmer Source Code for PIC16C73 ...............................................................................129
WORLDWIDE SALES AND SERVICE
Table of Contents
1998 Microchip Technology Inc. DS00680A-page 1
MAN680
INTRODUCTION
Radio Frequency Identification (RFID) systems use
radio frequency to identify, locate and track people,
assets, and animals. Passive RFID systems are
composed of three components – an interrogator
(reader), a passive tag, and a host computer. The tag
is composed of an antenna coil and a silicon chip that
includes basic modulation circuitry and non-volatile
memory. The tag is energized by a time-varying
electromagnetic radio frequency (RF) wave that is
transmitted by the reader. This RF signal is called a
carrier signal
. When the RF field passes through an
antenna coil, there is an AC voltage generated across
the coil. This voltage is rectified to supply power to the
tag. The information stored in the tag is transmitted
back to the reader. This is often called backscattering.
By detecting the backscattering signal, the information
stored in the tag can be fully identified.
DEFINITIONS
Reader
Usually a microcontroller-based unit with a wound out-
put coil, peak detector hardware, comparators, and
firmware des igned to tran smit energ y to a tag and rea d
information back from it by detecting the backscatter
modulation.
Tag
An RFID device incorporating a silicon memory chip
(usuall y with on-bo ard rectifi cation bridge and other RF
front-end d evic es), a wound or printe d input/output c oil,
and (at lower frequencies) a tuning capacitor.
Carrier
A Radio Frequency (RF) sine wave generated by the
reader to transmit energy to the tag and retrieve data
from th e tag. In these examples th e ISO frequencies of
125 kH z a nd 1 3.5 6 M H z ar e as su med; higher frequen-
cies are used for RFID tagging but the communication
methods are somewhat different. 2.45 GHz, for
examp le, uses a true R F li nk . 1 25 kHz and 13 .56 MH z ,
utilize transformer-type electromagnetic coupling.
Modulation
Periodic fluctuations in the amplitude of the carrier,
used to transmit data back from the tag to the reader.
Systems incorporating passive RFID tags operate in
ways that may seem unusual to anyone who already
understands RF or microwave systems. There is only
one transmitter – the passive tag is not a transmitter or
tran sponder in the p urest definiti on of the term, yet bidi-
rectional communication is taking place. The RF field
generated by a tag reader (the energy transmitter) has
three purposes:
1. Induce enough power into the tag coil to
energize the tag. Passive tags have no ba t tery
or other power source; they must derive all
power for operation from the reader field.
125 kHz and 13.56 MHz tag designs must
operate over a vast dynamic range of carrier
input, from the very near field (in the range of
200 VPP) to the maximum read distance (in the
range of 5 VPP).
2. Provide a synchronized clock source to the
tag. Most RFID tags divide th e carrier fre quency
down to generate an on-board clock for state
machines, counters, etc., and to derive the data
transmission bit rate for data returned to the
reader. Some tags, however, employ on-board
oscillators for clock generation.
3. Act as a carrier for return data from the tag.
Backscatter modulation requires the reader to
peak-detect the tag's modulation of the reader's
own carrier. See Section for additional
information on backscatter modulation.
Author: Pete Sorrells
Microchip Technology Inc.
Passive RFID Basics
AN680
DS00680A-page 2 1998 Microchip Technology Inc.
SYSTEM HANDSHAKE
Typical handshake of a tag and reader is as follows:
1. The reader continuously generates an RF
carrier sine wave, watching always for modula-
tion to occur. Detected modulation of the field
would indicate the presence of a tag.
2. A tag enters the RF field generated by the
reader. Once the tag has received sufficient
energy to operate correctly, it divides down the
carrier and begins clocking its data to an output
transistor, which is normally connected across
the coil inputs.
3. The tag’s output transistor shunts the coil,
sequentially corresponding to the data which is
being clocked out of the memory array.
4. Shunting the coil causes a momentary
fluctuation (dampening) of the carrier wave,
which is see n a s a s li ght c ha nge in amplitude of
the carrier.
5. The reader peak-detects the
amplitude-modulated data and processes the
resulting bitstream according to the encoding
and data modulation methods used.
BACKSCATTER MODULATION
This terminology refers to the communication method
used by a passive RFID tag to send data back to the
reader. By repeatedly shunting the tag coil through a
transistor, the tag can cause slight fluctuations in the
reader's RF carrier amplitude. The RF link behaves
essenti al ly as a transformer; as th e s ec on dary win din g
(tag coil) is mom entari ly shunt ed, the pr imar y wind ing
(reader coil) experiences a momentary voltage drop.
The reader must peak-detect this data at about 60 dB
down (about 100 mV riding on a 100V sine wave) as
shown in Figure 1.
This amplitude-modulation loading of the reader's
transmitted field provides a communication path back
to the reader. The data bits can then be encoded or
further modulated in a number of ways.
FIGURE 1: AMPLITUDE – MODULATED
BACKSCATTERING SIGNAL
100 mV
100V
1998 Microchip Technology Inc. DS00680A-page 3
AN680
DATA ENCODING
Data e nco di ng re fers to pro cess ing or a lte ring the da ta
bitstream in-between the time it is retrieved from the
RFID chip’s data array and its transmission back to th e
reader. The various encoding algorithms affect error
recovery, cost of implementation, bandwidth, synchro-
nization capability, and other aspects of the system
design. Entire textbooks are written on the subject, but
there are several popular methods used in RFID
tagging today:
1. NRZ (Non-Return to Zero) Direct. In this
method no data encoding is done at all; the 1’s
and 0’s are clocked from the data array directly
to the output transistor. A low in the
peak-de tected modulati on is a ‘0’ and a high is a
‘1’.
2. Differential Bipha se. Several different forms of
differential biphase are used, but in general the
bitstream being clocked out of the data array is
modified so that a transition always occurs on
every clock edge, and 1's and 0's are distin-
guished by the transitions within the middle of
the clock period. This method is used to embed
clocking information to help synchronize the
reader to the bitstream; and because it always
has a transition at a clock edge, it inherently
provides some error correction capability. Any
clock edge that does not contain a transition in
the data stream is in error and can be used to
rec onstruct the d a ta.
3. Biphase_L (Manchester). This is a variation of
biphase encodin g, in wh ich there is not al wa ys a
transition at the clock edge.
FIGURE 2: VARIOUS DATA CODING WAVEFORMS
Data
NRZ_L
Biphase_L
(Manchester)
Differential
Biphase_S
SIGNAL WAVEFORM DESCRIPTION
Digital Data
Non-Return to Zero - Level
‘1’ is represented by logic high level.
‘0’ is represented by logic low level.
Biphase - Level (Split Phase)
A level change occurs at middle of
every bit clock period.
‘1’ is represented by a high to low
level change at midclock.
‘0’ is represented by a low to high
level change at midclock.
Differential Biphase - Space
‘1’ is represented by a change in
level at start of clock.
‘0’ is represented by no change in
Bit Rate Clock Signal
(Direct)
CLK
A level change occurs at middle of
every bit clock period.
level at star t of clock.
101100011010
AN680
DS00680A-page 4 1998 Microchip Technology Inc.
DATA MODULATION
Although all the data is transferred to the host by
amplitude-modulating the carrier (backscatter modula-
tion), the actual modulation of 1’s and 0’s is accom-
plished with three additional modulation methods:
1. Direct. In direct modulation, the Amplitude
Modulation of the backscatter approach is the
only modu l at i on u se d. A h i gh i n t h e envelop e is
a ‘1’ an d a low is a ‘0’. Direct modulat ion can pro-
vide a high data rate but low noise immunity.
2. FSK (Frequency Shift Keying). This form of
modulation uses two different frequencies for
data transfer; the most common FSK mode is
Fc/8/10. In other w ords, a ‘0 ’ is trans mitted as a n
amplitude-modulated clock cycle with period
corresponding to the carrier frequency divided
by 8, and a ‘1’ is transmitted as an
amplitude-modulated clock cycle period corre-
sponding to the carrier frequency divided by 10.
The amplitude modulation of the carrier thus
switches from Fc/8 to Fc/10 corresponding to 0's
and 1's in the bits tream, and the reader h as only
to count cycles between the peak-detected
clock edges to decode the data. FSK allows for
a simple reader design, provides very strong
noise immunity, but suffers from a lower data
rate than some other for ms of data modulation.
In Figure 3, FSK data modulation is used with
NRZ encoding:
3. PSK (Phase Shift Keying). This metho d of data
modulation is similar to FSK, except only one
frequenc y is us ed, and th e shift b etween 1's and
0's is accomplished by shifting the phase of the
bac ksc atter cl oc k b y 1 80 deg rees . Two commo n
types of PSK are:
• Change phase at any ‘0’, or
• Change phase at any data change
(0 to 1 or 1 to 0).
PSK provides fairly good noise immunity, a
moderately simple reader design, and a faster
data rate than FSK. Typical applications utilize a
backscatter clock of Fc/2, as shown in Figure 4.
FIGURE 3: FSK MODULATED SIGNAL, FC/8 = 0, FC/10 = 1
FIGURE 4: PSK MODULATED SIGNAL
8 cycles = 0 8 cycles = 0 10 cycles = 1 10 cycles = 1 8 cycles = 0
Phase
Shift Phase
Shift Phase
Shift Phase
Shift
1998 Microchip Technology Inc. DS00680A-page 5
AN680
ANTICOLLISION
In many existing applications, a single-read RFID tag is
sufficient and even necessary: animal tagging and
access control are examples. However, in a growing
numbe r of new app lica ti ons, t he s imulta neo us r eadi ng
of several tags in the same RF field is absolutely criti-
cal: librar y books, airline baggage, gar ment, and retail
applications are a few.
In order to read multiple tags simultaneously, the tag
and reader must be designed to detect the condition
that more than one tag is active. Otherwise, the tags
will all ba cksca tter the carrier at the s ame time, and the
amplitude-modulated waveforms shown in Figures 3
and 4 would be garbled. This is referred to as a
collision
. No data would be transferred to the reader.
The tag/reader interface is similar to a serial bus, even
though the “bus” trav els through the a ir . In a wired serial
bus application, arbitration is necessary to prevent bus
contention. The RFID interface also requires arbitration
so that only one tag transmits data o ver the “b us” at one
time.
A number of different methods are in use and in
development today for preventing collisions; most are
patented or patent pending, but all are related to
making sure that only one tag “talks” (backscatters) at
any one time . See the
MCRF250 Data Sheet
(page 15)
and the
FSK Anticollision Reader Reference Design
(page 99) chapters for more information.
AN680
DS00680A-page 6 1998 Microchip Technology Inc.
NOTES:
1998 Microchip Technology Inc. DS21219D-page 7
MMCRF200
FEATURES
• Contactless programmable after encaps ulation
• Read only data transmission
• 96 or 128 bits of One-Time Programmable (OTP)
user memory (also supports 48 and 64-bit
protocols)
• Typical operates at 125 kHz
• On chip rectifier and voltage regulator
• Ultra low power operation
• Factory programming and device serialization
available
• Encoding options:
- NRZ Direct, Differential Biphase, Manchester
Biphase
• Modulation options:
- Direct, FSK, PSK (change on data change),
PSK (change at the beginning of a one)
APPLICATION
PACKAGE TYPE
DESCRIPTION
This device is a Radio Frequency Identification (RFID)
tag t hat provides a bid irec tiona l inte rfac e for progra m-
ming and reading the contents of the user array. The
device is powered by an external RF transmitter
through inductive coupling. When in read mode, the
device transmits the contents of its memory array by
damping (modulating) the incoming RF signal. The
reader is able to detect the damping and decodes the
data being transmitted. Code length, modulation
option, encoding option, and bit rate are set at the
factory to fit the needs of particular applications.
The user memory array of this device can be
programmed contactlessly after encapsulation. This
allows the user to keep encapsulated blank tags in
stock for on-demand personalization. The tags can
then be programmed with data as they are needed.
These devices ar e available in die, wafe r, PDIP, SOIC,
and COB module form. The encoding, modulation,
frequency, and bit rate options are specified by the
customer and programmed by Microchip Technology
Inc. prior to shipment. Array programming and
serialization (SQTP) can also be arranged upon
request. See TB023 (page 23) for more information.
BLOCK DIAGRAM
MCRF200
Transmitter/
Receiver
RF
Signal
Data
PDIP/SOIC
VAVB
1
2
3
4
8
7
6
5
NC
NC
NC
NC
NC
NC
Column
Memory
Array
Vcc
Vss
Rectifier
Clock
Generator
coil
connections
Decode
Row
Decode
Modulation
Control
Counter
Data
Load
Contactless Programmable Passive RFID Device
MCRF200
DS21219D-page 8 1998 Microchip Technology Inc.
1.0 ELECTRICAL
CHARACTERISTICS
1.1 Maximum Ratings*
Storage temperature....................................- 65°C to +150°C
Ambient temp. with power applied ................- 40°C to +125°C
Maximum current into coil pads .......... ....... ............ .......50 mA
*Notice: Stresses above those listed under “Maximum ratings” may
cause permanent damage to the device. This is a stress rating only and
functional operation of the device at those or any other conditions
above those indicated in the operati onal listin gs of this spec ificat ion is
not implied. Exposure to maximum rating conditions for extended peri-
ods may affect device reliability.
TABLE 1-1: PAD FUNCTION TABLE
FIGURE 1-1: DIE PLOT TABLE 1-3 RFID PAD COORDINATES
(MICRONS)
Name Function
VA,VBCoil connection
NC No connection, test pad
TABLE 1-2: AC AND DC CHARACTERISTICS
All parameters apply across the
specified operating ranges
unless otherwis e noted.
Industrial (I): Tamb = -40°C to +85°C
Parameter Symbol Min. Typ. Max. Units Conditions
Clock frequency FCLK 100 — 150 kHz
Contactless programming time TWC — 2 — s 128-bit array
Data retention 200 — — Years 25°C
Coil current (Dynamic) ICD —50 µA
Operating current IDD —5 µAVCC = 2V
Turn-on-voltage (Dynamic) for
modulation VAVB10 — — VPP
VCC 2——VDC
Input Capacitance CIN — 2 — pF Betwe en VA and VB
VBVA
NC NC NC NC
Passivation
Openings
Pad
Name Pad
Width Pad
Height Pad
Center X Pad
Center Y
VA90.0 90.0 427.50 -734.17
VB90.0 90.0 -408.60 -734.17
Note 1: All coordinate s are re ferenced from the
center of the die.
2: Die size 1.1215 mm x 1.7384 mm.
1998 Microchip Technology Inc. DS21219D-page 9
MCRF200
2.0 FUNCTIONAL DESCRIPTION
The RF section generates all the analog functions
needed by the transponder. These include rectification
of the carrier, on-chip regulation of VPP (pr ogramming
voltage), and VDD (operating voltage), as well as high
voltage clamping to prevent excessive voltage from
being applied to the transponder. This section gener-
ates a system clock from the interrogator carrier of the
same frequency, detects carrier interrupts, and modu-
lates the tuned LC antenna for transmission to the
interrogator . The chip detects a power-up condition and
resets the transponder when sufficient voltage
develops.
2.1 Rectifier – AC Clamp
The A C voltage generated by the tr ansponder tuned LC
circuit is full wave rectifi ed. This unregulated vol tage is
used as the m axim um D C suppl y v ol tag e for th e rest of
the chip. The peak voltage on the tuned circuit is
clamped by the internal circuitry to a safe level to
prevent damage to the IC. This voltage is adjusted
during programming to allow sufficient programming
v olt age to the EEPR OM.
2.2 Coil Load Modulation
The MCRF200 communicates to the reader by
AM-modulating the coil voltage across the tuned LC
circuit.
2.3 VDD Regulator
The device generates a fixed supply voltage from the
unregulated coil voltage.
2.4 VPP Regulator
This regulates a programming voltage during the pro-
gram m ing mode . The voltage is used fo r the EEPROM
arra y to perform block erasure of the memory as well as
single-bit programming during both contact and
contactless programming. During reading, this voltage
is l evel- shifte d down an d kept bel ow the p rogrammi ng
voltages to insure that the part is not inadvertently
programmed.
2.5 Clock Generator
This circ uit gener ates a clo ck ba sed on the in terrogator
frequency. This clock is used to der ive all timing in the
tag, including the baud rate, modulation rate, and
prog r am ming rate.
2.6 IRQ Detector
This circuitry detects an interrupt in the continuous
electromagnetic field of the interrogator. An IRQ
(interrupt request) is defined as the absence of the
electromagnetic field for a specific number of clock
cycles. This feature is used during contactless
programming.
2.7 Power-On-Reset
This circuit generates a power-on-reset when the tag
first enters the interrogator field. The reset releases
when sufficient power has developed on the VDD
regulator to allow correct operation. The reset trip
points are set such that sufficient voltage across VDD
has developed, which allows for correct clocking of the
logic for reading of the EEPROM and configuration
data, and correct modulation.
2.8 Modulation Logic
This l ogic acts upon the serial d ata bein g read from the
EEPROM and performs two operations on the data.
The logic first encodes the data according to the
configuration bits CB6 and CB7. The data can be sent
out direct to the modulation logic or encoded Biphase
Differential, Biphase Manchester or Manchester with
IDI option.
The encod ed data is then eit her passed NRZ D irect out
to modulate the coil, or FSK modulated, or PSK
modula ted with chang es on the change of dat a, or PSK
with changes on the bit edge of a one. Configuration
bits CB8 and CB9 determine the modulation option.
CB10 is used if the PSK opt ion has been selec ted, an d
determines if the return carrier rate is FCLK/2 or FCLK/4.
MCRF200
DS21219D-page 10 1998 Microchip Technology Inc.
3.0 CONFIGURATION LOGIC
CONTROL BIT REGISTER
The configuration register determines the operational
parameters of the device. The configuration register
cannot be program med contactless ly; it is progr ammed
during wafer probe at the Microchip factory. CB11 is
always a zero; CB12 is set when successful contact or
contactless programming of the data array has been
completed. Once CB12 is set, device programming and
erasing is disabled. Figure 3-1 contains a description of
the control register bit functions.
3.1 Organization
The configuration bit register directly controls logic
blocks which generate the baud rate, memory size,
encoded data, and modulated data. This register also
con tains bits w hich lock the data array.
3.2 Baud Rate Timing
The chi p w il l a cc es s data at a baud rate de termined by
bits CB2, CB3, CB4, and CB5 of the configuration
register. CB2, CB3, and CB4 dete rmine the retu rn data
rate (CACLK). The default rate of FCLK/128 is used for
contact and contactless programming. Once the array
is successfully programmed, the lock bit CB12 is set.
When the lock bit is cl eare d, p r og ramming and er as in g
the device bec omes permanentl y disab le d. The confi g-
ura tion register has no effec t on de vice tim ing until aft er
the EEPROM data array is programmed. If CB2 is set
to a one and CB5 is set to a one, the 1.5 bit SYNC word
option is enabled.
3.3 Column and Row Decoder Logic and
Bit Counter
The column and row decoders address the EEPROM
array at the clock rate and generate a serial data
stream for modulation. This data stream can be up to
128 bits in length. The size of the stream is user
programmable with CB1 and can be set to 96 or 128
bits . Data leng ths of 48 an d 64 bits are av ailab le by p ro-
gramming the data twice in the array, end-to-end. The
data is then en co ded b y t he mod ulatio n logi c. The data
length during contactless programming is 128 bits.
The colum n and row decoders route the prop er vol tage
to the array for programming and reading. In the
programming modes, each individual bit is addressed
serially from bit 1 to bit 128.
1998 Microchip Technology Inc. DS21219D-page 11
MCRF200
FIGURE 3-1: CONFIGURATION REGISTER
CB12CB11 CB10 CB9 CB8 CB7 CB6 CB5 CB4 CB3 CB2 CB1 ARRAY SIZE
CB1 = 1 128-bit user array
CB1 = 0 96-bit user array
TIMING
SYNC WORD
CB5 = 1 1.5-bit sync word enable
CB5 = 0 1.5-bit sync word disable
DATA ENCODING
CB6 = 0; CB7 = 0 NRZ_L (Direct)
CB6 = 0; CB7 = 1 Biphase_S (Differential)
CB6 = 1; CB7 = 0 Biphase_L (Manchester)
CB6 = 1; CB7 = 1 (Not Used)
MODULATION OPTIONS
CB8 = 0; CB9 = 0 FSK 0 = Fc/8, 1 = Fc/10
CB8 = 0; CB9 = 1 Direct
CB8 = 1; CB9 = 0 psk_1
(phase change on change of data)
CB8 = 1; CB9 = 1 psk_2
(phase change at beginning of a one)
PSK RATE OPTION
CB10 = 1 clk/4 carrier
CB10 = 0 clk/2 carrier
(READ ONLY)
CB11 = 0
ARRAY LOCK BIT (READ ONLY)
CB12 = 0 array not locked
CB12 = 1 array is locked
CB2 CB3 CB4 Rate
0 0 0 MOD128
0 0 1 MOD100
010MOD80
011MOD32
100MOD64
101MOD50
110MOD40
111MOD16
MCRF200
DS21219D-page 12 1998 Microchip Technology Inc.
4.0 MODES OF OPERATION
The device has two basic modes of operation: Native
Mode and Read Mode.
4.1 Native Mode
In native mode, a transponder will have an
unprog ramme d arra y and will be in the defa ult mode for
contactless programming (default baud rate FCLK/128,
FSK, NRZ_direct).
4.2 Read Mode
The sec ond mo de i s a re ad m od e aft er th e co nta ctl es s
or contact programming has been completed and for
the rest of the lifetime of the device. The lock bit CB12
will be set, and when the tr ansp onder is po wered, it w ill
have the ab i li t y to tra n smi t a cc o rd ing t o t h e pr o t oc o l in
the configuration register.
FIGURE 4-1: TYPICAL APPLICATION CIRCUIT
Pad VB
Pad VA
Input capacitance: 2 pF
Energy
Data
2.2 nF
To reader
amplifier/filter
From
oscillator
IAC 740 µH 4.05 mH 390 pF
fres 1
2πLC
------------------ 125
kHz
==
125 kHz
MCRF200
1998 Microchip Technology Inc. DS21219D-page 13
MCRF200
MCRF200 PRODUCT IDENTIFICATION SYSTEM
To order or obtain information, e.g., on pricing or delivery, refer to the factory or the listed sales office.
Configuration:
Hex Code = Three digit hex value to be programmed into the
configuration register. Three hex characters corre-
spond to 12 binary bits. These bit s a r e prog rammed
into the configuration register MSB first (CB12,
CB11…CB1). See the example belo w.
Package:
WF = Sawed wafer on frame (7 mil backgrind)
W = Wafer (11 mil backgrind)
S = Dice in waffle pack
SN = 150 mil SOIC
P=PDIP
1C = 0.45 mm COB module with 1000 pF capacitor
3C = 0.70 mmCOB module with 330 pF capacitor
Temperature I= -40°C to +85°C
Range:
Sample Part MCRF200-I /W00A
Number:
MCRF200-I/W00A = 125 kHz, industrial temperature, wafer package,
contactlessly programmable, 96 bit,
FSK Fc/8 Fc/10, direct encoded, Fc/50 data return
rate tag. The configuration register is:
CB12 CB11 CB10 CB9 CB8 CB7 CB6 CB5 CB4 CB3 CB2 CB1
MCRF 200 – I /WFxxx
000000 000 110
MCRF200
DS21219D-page 14 1998 Microchip Technology Inc.
NOTES:
1998 Microchip Technology Inc. DS21267C-page 15
MMCRF250
FEATURES
• Antic oll is ion fe ature to resolv e m ultiple tags in the
same RF field
• Read-only data transmission
• 96 or 128 bits of One-Time Programmable (OTP)
user memory (also supports 48 and 64-bit
protocols)
• Operates up to 150 kHz
• On-chip rectifier and voltage regulator
• Low power operation
• Factory programming and device serialization
available
• Encoding options:
- NRZ Direct, Differential Biphase, Manchester
Biphase, Biphase IDI
• Modulation options:
- FSK, Direct, PSK (change on data change),
PSK (change at the beginning of a one)
• Contactless programmable after encaps ulation
DESCRIPTION
This device is a Radio Frequency Identification (RFID)
tag that provides a variety of operating modes. The
device is powered by an external RF transmitter
(reader) through inductiv e coupling. Whe n in the reader
field, the de vic e will transm it the contents of i ts memo ry
array by d ampi ng (mo dulati ng) the incom ing RF si gnal.
A reader is able to d etect the dampin g and decode s the
data being transmitted. Code length, modulation
option, encoding option and bit rate are set at the
factory to fit the needs of particular applications.
APPLICATION
The MCRF250 is equipped with an anticollision
feature that allows multiple tags in the same field to
be read simultaneously. This revolutionary feature
eliminates the issue of data corruption due to
simult ane ous transm iss ions from multiple tags .
The user memory array of this device can be
programmed contactlessly after encapsulation. This
allows the user to keep encapsulated blank tags in
stock for on-demand personalization. The tags can
then be programmed with data as they are needed.
These devices are availa ble in die form or packaged in
SOIC, PDIP or COB modules. The encoding,
modulation, frequency, and bit rate options are
specified by the customer and programmed by
Microc hip Techno log y In c. prior to shipmen t. Arra y pro-
gramming and serialization (SQTP) can also be
arra nged upon reque st. See TB02 3 (p age 23) for mo re
information.
BLOCK DIAGRAM
MCRF250
Transmitter/
Receiver
RF
Signal
Data
Column
Memory
Array
VCC
VSS
Rectifier
Clock
Generator
Coil
Connections
Decode
Row
Decode
Modulation
Control
Counter
Data
Modulation
Anticollision
Circuitry
Circuit
Contactless Programmable Passive RFID Device With Anticollision
MCRF250
DS21267C-page 16 1998 Microchip Technology Inc.
1.0 ELECTRICAL
CHARACTERISTICS
1.1 Maximum Ratings*
Storage temperature.....................................-65°C to +150°C
Ambient temp. with power applied ................- 40°C to +125°C
Maximum current into coil pads ................... ...... ...........50 mA
*Notice: Stresses above those listed under “Maximum ratings” may
cause permanent damage to the device. This is a stress rating only and
functional operation of the device at those or any other conditions
above those indicated in the operati onal listin gs of this spec ificat ion is
not implied. Exposure to maximum rating conditions for extended peri-
ods may affect device reliability.
TABLE 1-1: PAD FUNCTION TABLE
FIGURE 1-1: DIE PLOT
FIGURE 1-2: PIN DIAGRAM
Name Function
VA,VBCoil connection
NC No connection, test pad
TABLE 1-2: AC AND DC CHARACTERISTICS
All parameters apply across the speci-
fied operating ranges unless otherwise
noted.
Industrial (I): Tamb = -40°C to +85°C
Parameter Symbol Min. Typ. Max. Units Conditions
Clock frequency FCLK 100 — 150 kHz
Contactless programming time TWC — 2 — s 128-bit array
Data retention 200 — — Years 25°C
Coil current (Dynamic) ICD —50 µA
Operating current IDD —2 µA
Turn-on-voltage (Dynamic)
for modulation VAVB10 — — VPP
VCC 2——VDC
VBVA
NC NC NC NC TABLE 1-3: RFID PAD COORDINATES
(MICRONS)
Passivation
Openings
Pad
Name Pad
Width Pad
Height Pad
Center X Pad
Center Y
VA90.0 90.0 427.50 -734.17
VB90.0 90.0 -408.60 -734.17
Note 1: All coord ina tes are refe renc ed from the ce n-
ter of the die.
2: Die size 1.1215 mm x 1.7384 mm.
PDIP, SOIC
8
7
6
5
1
2
3
4
MCRF250
NC
NC
NC
NC
NC
NC
VAVB
MCRF250
1998 Microchip Technology Inc. DS21267C-page 17
2.0 FUNCTIONAL DESCRIPTION
The RF section generates all the analog functions
needed by the transponder. These include rectification
of the carrier, on-chip regulation of VPP (pr ogramming
voltage), and VDD (operating voltage), as well as high
voltage clamping to prevent excessive voltage from
being applied to the device. This section generates a
system clock from the interrogator carrier frequency,
detects carrier interr upts and modulates the tuned LC
antenna for transmission to the interrogator. The chip
detects a power up condition and resets the transpon-
der w hen sufficient voltage develops.
2.1 Rectifier – AC Clamp
The AC voltage induced by the tuned LC circuit is full
wave rectified. This unregulated voltage is used as the
DC supply voltage for the rest of the chip. The peak
voltage on the tuned circuit is clamped by the inter nal
circuitry to a safe level to prevent damage to the IC.
This voltage is adjusted during programming to allow
sufficient programming voltage to the EEPROM.
2.2 Coil Load Modulation
The MCRF250 communicates by shunting a transistor
across the tuned LC circuit, which modulates the
received RF field.
2.3 VDD Regulator
The device generates a fixed supply voltage from the
unregulated coil voltage.
2.4 VPP Regulator
This regulates a programming voltage during the
programming mode. The voltage is switched into the
EEPROM array to perform block erasure of the
memory as well as single bit programming during both
contact and contactless programming. During reading
this voltage is level shifted down and kept below the
programming voltages to insure that the part is not
inadvertently programmed.
2.5 Clock Generator
This ci rcuit g enera tes a c loc k wi th a frequen cy equ al to
the interrogator frequency. This clock is used to derive
all timing in the device, including the baud rate,
modulation rate, and programming rate.
2.6 IRQ Detector
This circuitry detects an interrupt in the continuous
electromagnetic field of the interrogator. An IRQ
(interrupt request) is defined as the absence of the
electromagnetic field for a specific number of clock
cycles. Detection of an IRQ will trigger the device to
enter the Anticollision mode. This mode is discussed in
detail in Section 5.0.
2.7 Power-On-Reset
This circuit generates a power-on-reset when the tag
first enters the interrogator field. The reset releases
when sufficient power has developed on the VDD
regulator to allow correct operation. The reset trip
points are set such that sufficient voltage across VDD
has developed which allows for correct clocking of the
logic for reading of the EEPROM and configuration
data, and correct modulation.
2.8 Modulation Logic
This l ogic acts upon the serial d ata bein g read from the
EEPROM and performs two operations on the data.
The logic first encodes the data according to the
configuration bits CB6 and CB7. The data can be sent
out direct to the modulation logic or encoded
Biphase _s (Different ial), Bip hase_l (Man chester) o r IDI
(Manchester).
The encod ed data is then eit her passed NRZ D irect out
to modulate the coil, or FSK modulated, or PSK
modulated with phase changes on the change of data,
or PSK with phase changes on the bit edge of a one.
Configuration bits CB8 and CB9 determine the
modulation option. CB10 is used if the PSK option has
been selected and determines whether the return
carrier rate is FCLK/2 or FCLK/4.
MCRF250
DS21267C-page 18 1998 Microchip Technology Inc.
3.0 CONFIGURATIONLOGIC
3.1 Control Bit Register
The configuration register determines the operational
parameters of the device. The configuration register
can not be programmed contactlessly; it is
programmed during wafer probe at the Microchip
factory. CB11 is always a one; CB12 is set when
successful contact or contactless programming of the
data array has been completed. Once CB12 is set,
programming and erasing of the device is disabled.
Figure 3-1 co ntains a desc ription of th e contro l regis ter
bit functions.
3.2 Organization
The configuration bit register directly controls logic
blocks, which generate the baud rate, memory size,
encoded data, and modulated data. This register also
con tains bits w hich lock the data array.
3.3 Baud Rate Timing
The chi p w il l a cc es s data at a baud rate de termined by
bits CB2, CB3, CB4, and CB5 of the configuration
register. CB2, CB3, and CB4 dete rmine the retu rn data
rate (CACLK). The default rate of FCLK/128 is used for
contact and contactless programming. Once the array
is successfully programmed, the lock bit CB12 is set.
When the lock bit is set, programming and erasing the
device becomes permanently disabled. The
configuration register has no effect on device timing or
modulation until after the EEPROM data array is
prog r am me d. If C B2 is set to a one and CB5 is set to a
one, the 1.5 bit SYNC word option is enabled.
3.4 Column and Row Decoder Logic and
Bit Counter
The column and row decoders address the EEPROM
array at the CACLK rate and generate a serial data
stream for modulation. This data stream can be up to
128 bits in length. The size of the stream is user
programmable with CB1, and can be set to 96 or 128
bits. Data lengths of 48 and 64 bits are available by
programming the data twice in the array end to end.
The data is then encoded by the modulation logi c. The
data length during contactless programming is 128 bits.
The colum n and row decoders route the prop er vol tage
to the array for programming and reading. In the
programming modes, each individual bit is addressed
serially from bit 1 to bit 128.
MCRF250
1998 Microchip Technology Inc. DS21267C-page 19
FIGURE 3-1: CONFIGURATION REGISTER
CB12CB11 CB10 CB9 CB8 CB7 CB6 CB5 CB4 CB3 CB2 CB1 ARRAY SIZE
CB1 = 1: 128-bit user array
CB1 = 0: 96-bit user array
TIMING
SYNC WORD
CB5 = 1: 1.5-bit sync word enable
CB5 = 0: 1.5-bit sync word disable
DATA ENCODIN G
CB6 = 0; CB7 = 0 nrz_I (direct)
CB6 = 0; CB7 = 1 biphas e_s (diff erential)
CB6 = 1; CB7 = 0 biphase_I (manchester)
CB6 = 1; CB7 = 1 (Not Used)
MODULATION OPTIONS
CB8 = 0; CB9 = 0 FSK 0 = /8, 1 = /10
CB8 = 0; CB9 = 1 Direct
CB8 = 1; CB9 = 0 psk_1
(phase change on change of data)
CB8 = 1; CB9 = 1 psk_2
(phase change at beginning of a one
PSK RATE OPTION
CB10 = 1 clk/4 carrier
CB10 = 0 clk/2 carrier
(READ ONLY)
CB1 1 = 1
ARRAY LOCK BIT (READ ONLY)
CB12 = 0 array not locked
CB12 = 1 array is locked
CB2 CB3 CB4 Rate
000MOD128
001MOD100
010MOD80
011MOD32
100MOD64
101MOD50
110MOD40
111MOD16
MCRF250
DS21267C-page 20 1998 Microchip Technology Inc.
4.0 MODES OF OPERATION
The device has two basic modes of operation: Native
Mode and Read Mode.
4.1 Native Mode
In native mode, the MCRF250 will have an
unprog ramme d arra y and will be in the defa ult mode for
contactless programming (default baud rate FCLK/128,
FSK, NRZ_direct).
4.2 Read Mode
The sec ond mo de i s a re ad m od e aft er th e co nta ctl es s
or contact programming has been completed and for
the rest of the lifetime of the device. The lock bit CB12
will be set, and the transponder will have the ability to
transmit when powered and enter the anticollision algo-
rithm.
FIGURE 4-1: TYPICAL APPLICATION CIRCUIT
Pad VB
Pad VA
Input parasitic
RF Energy
Data
2.2 nF
To reader
amplifier/
From
carrier
IAC 740 µH 4.05 mH 390 pF
fres 1
2πLC
------------------ 12 5 kHz==
125 kHz
signal
generator
data detector
capacitance 2pF
(Backscattering
Signal)
MCRF250
MCRF250
1998 Microchip Technology Inc. DS21267C-page 21
5.0 ANTICOLLISION
The anticollision feature is enabled when the array is
locked. In this mode, the MCRF250 has the ability to
stop transmitting when a collision has occurred. The
device will begin transmitting again when its internal
anticollision algorithm indicates that it is time to do so.
Multiple tags can enter the same reader field and be
read b y the rea der in a sh ort pe riod of ti me . The reader
must provide “gaps” (RF field off) at proper timing
inte r vals as shown in F igur e 5-1 in o rder t o info r m the
MCRF250 of collisions, and to sequence from one tag
to another.
FIGURE 5-1: ANTICOLLISION
FLOWCHART
Begin
Provide Gap*
W ait 5-bit times
Is
Read Tag
Is
only one tag
modulating?
modulation
present?
Provide gap in the
first half of the first
bit time to make
tag stop
transmitting
No
No
Yes
Yes
Note: *Gap = lack of RF carrier signal
= 60 µs ± 20%.
MCRF250
DS21267C-page 22 1998 Microchip Technology Inc.
MCRF250 PRODUCT IDENTIFICATION SYSTEM
To order or obtain information, e.g., on pricing or delivery, refer to the factory or the listed sales office.
Configuration:
Hex
Code = Thr ee digit hex value to be programmed in to the
configuration register. Three hex characters corre-
spond to 12 bin ary bits. These bit s are progr ammed
into the configuration register MSB first (CB12,
CB11…CB1). See the example below.
Package:
WF = Sawed wafer on frame (7 mil backgrind)
W=Wafer
S = Dice in wafer pack
SN = 150 mil SOIC
P=PDIP
1C = COB module with 1000 pF capacitor
3C = COB module with 330 pF capacitor
Temperature I = –40°C to +85°C
Range:
Device: 250 = 125 kHz
Sample Part MCRF250-I /40A
Number:
MCRF250-I/W40A = 125 kHz, Industrial temperature, wafer package,
anticollision, 96 bit, FSK/8 /10,direct encoded, F/50
data return rate tag. The configuration register is:
CB12 CB11 CB10 CB9 CB8 CB7 CB6 CB5 CB4 CB3 CB2 CB1
MCRF250 - I /WFxxx
000010 000 110
1998 Microchip Technology Inc. DS91023A-page 23
MTB023
INTRODUCTION
The MCRF200 and MCRF250 are 125 kHz RF tags,
which can be contact or contactlessly programmed.
The contact progr amming of the device is performed by
Microchip Technolog y , Inc. upon customer reques t. The
customer can choose any ID code suitable to their
applic ation subject to a m in im u m o rder quantity. These
devices can also be contactlessly programmed after
encaps ulation using th e M ic roc hi p m ic roID co ntactl ess
programmer (PG103001).
DEFINITIONS
First, the customer has to define the following operation
options of the MCRF200 and MCRF250 (refer to
individual data sheets page 7 and page 15,
respectively):
Second, the ID codes and series numbers must be
supplied by the customer or an algorithm can be
specified by the customer. This section describes only
the case in which actual serial numbers are supplied.
The customer must supply the ID codes and series
numb ers on floppy disk or vi a em ail . The c ode s sh ould
conform to the SQTP format below:
FILE SPECIFICATION
SQTP codes supplied to Microchip must comply with
the following format:
The ID code file is a plain ASCII te xt file from flopp y disk
or email (no headers).
The code files should be compressed. Please make
self-extracting files.
The cod e files are used in alphabeti cal order of th eir file
nam es (includi ng letters and numbe rs).
Used (i.e., programmed) code files are discarded by
Microchip after use.
Each line of the code file must contain one ID code for
one IC.
The code is in hexadecimal format.
The code line is exactly as long as the selected code
length (e.g., code length = 64, ID code = 16 hex char-
acters = 64-bit number).
Each line must end with a carriage return.
Each hexadecimal ID code must be preceded by a
deci ma l series number.
Series number and ID code must be separated by a
space.
The series number must be unique and ascending to
avoid double programming.
The se ries num be rs of tw o c on s ec uti ve fil e s mus t al so
count up for proper linking.
FIGURE 1: EXAMPLE OF TWO CODE FILES, CODE LENGTH = 64 BITS
• Bit rate Defined as clocks per bit e.g.,
Fc/16, Fc/32, Fc/40, Fc/50, Fc/64,
Fc/80, Fc/100, and Fc/128
• Modulation FSK, PSK1, PSK2, ASK Direct
• Encoding NRZ_L (Direct), Bip hase_ L
(Manchester), Differential
Biphase_S
• Code length 32, 48, 64, 96, and 128 bits
FILE0000.TXT
00001 A34953DBCA001F26
00002 C4F55308B492A783
00003 38FAC359981200B7
" "
12345 9278256DCAFE8756
FILE0001.TXT
12346 EA43786937DCFB87
12347 459724FCA487ED24
" "
" "
Last Code
Serial Number Carriage Return
Filename
Code File
Next Code
ID Code Space Necessary
Contact Programming Support
TB023
DS91023A-page 24 1998 Microchip Technology Inc.
NOTES:
1998 Microchip Technology Inc. DS00678B-page 25
MAN678
INTRODUCTION
In a Radio Frequency Identification (RFID) application,
an antenna coil is needed for two main reasons:
• To transmit the RF carrier signal to power up the
tag
• To receive data signals from the tag
An RF signal can be radiated effectively if the linear
dimension of the antenna is comparable with the
wavelength of the operating frequency. In an RFID
applic ation utili zing th e VLF (100 kHz – 50 0 kHz) band,
the wavelength of the operating frequency is a few
kilometers (λ = 2.4 Km for 125 kHz s ign al). Bec au se of
its long wavelength, a true antenna can never be
formed in a limited space of the device. Alternatively, a
small loop antenna coil that is resonating at the
frequency of the interest (i.e., 125 kHz) is used. This
type of antenna utilizes near field magnetic induction
coupling between transmitting and receiving antenna
coils.
The field produced by the small dipole loop antenna is
not a propagating wave, but rather an attenuating wave.
The field strength falls off with r-3 (where r = distance
from the antenna). This near field behavior (r-3) is a
main limiting factor of the read range in RFID
applications.
When the time-varying magnetic field is passing
through a coil (antenna), it induces a voltage across the
coil terminal. This voltage is utilized to activate the
passive tag device . Th e ante nna c oil m ust be desi gned
to maximize this indu ced voltage.
This app licat ion not e is written as a re ference guide for
antenna coil design ers and appl ication engi neers in the
RFID industry. It reviews basic electromagnetics
theories to understand the antenna coils, a procedure
for coil design, calculation and measurement of
inductance, an antenna-tuning method, and the
relationship between read range vs. size of antenna
coil.
REVIEW OF A BASIC THEORY FOR
ANTENNA COIL DESIGN
Current and Magnetic Fields
Ampere’s law states that current flowing on a cond uctor
produces a magnetic field around the conductor.
Figure 1 shows the magnetic field produced by a
current element. The magnetic field produced by the
current on a round conductor (wire) with a finite length
is gi ven by:
EQUATION 1:
where:
In a special case with an infinitely long wire where
α1= -180° and α2 = 0°, Equation 1 can be rewritten as:
EQUATION 2:
FIGURE 1: CALCULATION OF
MAGNETIC FIELD B AT
LOCATION P DUE TO
CURRENT I ON A STRAIGHT
CONDUCTING WIRE
Author: Youbok Lee
Microchip Technology Inc.
I= current
r= distance from the center of wire
µo= permeability of free space and given as
µo=4 π x 10-7 (Henry/meter)
BφµoI
4πr
---------α2
cos α1
cos–()= Weber m2
⁄()
BφµoI
2πr
---------= Weber m2
⁄()
Wire
dL
I
r
0B (into th e pag e)
P
R
α2
α
α1
Ζ
X
RFID Coil Design
AN678
DS00678B-page 26 1998 Microchip Technology Inc.
The magn etic field produced b y a ci rcular loo p antenna
coil with N-turns as shown in Figure 2 is found by:
EQUATION 3:
where:
Equation 3 indicates that the magnetic field produced
by a loop antenna decays with 1/r3 as shown in
Figure 3. This near-field decaying behavior of the
magnetic field is the main limiting factor in the read
range of the RFID device. The field strength is
maximum in the plane of the loop and directly
proportional to the current (I), the number of turns (N),
and the surface area of the loop.
Equation 3 is frequently used to calculate the
ampere-turn requirement for read range. A few
examples that calculate the ampere-turns and the field
intensi ty necess ary to po we r the tag will be giv en in the
following sections.
FIGURE 2: CALCULATION OF
MAGNETIC FIELD B AT
LOCATION P DUE TO
CURRENT I ON THE LOOP
FIGURE 3: DECAYING OF THE
MAGNETIC FIELD B VS.
DISTANCE r
a= radius of loop
BzµoINa2
2a2r2
+()
32⁄
---------------------------------=
µoINa2
2
------------------ 1
r3
----
=forr2>>a2αR
r
y
I
coil
Bz
P
z
a
r
r-3
B
Note: The magnetic field produced by a
loop antenna drops off with r-3.
1998 Microchip Technology Inc. DS00678B-page 27
AN678
INDUCED VOLTAGE IN ANTENNA
COIL
Faraday’s law states a time-varying magnetic field
through a surface bounded by a closed path induces a
voltage around the loop. This fundamental principle
has important consequences for operation of passive
RFI D devices .
Figure 4 shows a simple geometry of an RFID
application. When the tag and reader antennas are
within a proximity distance, the time-var ying magnetic
field B that is produced by a reader antenna coil
induces a voltage (called electromotive force or simply
EMF) in the tag antenna coil. The induced voltage in
the coil causes a flo w of current in the coil . This is called
Faraday’s law.
The induc ed v olta ge on the tag an tenna co il is equa l to
the time rate of change of the magnetic flux Ψ.
EQUATION 4:
where:
The negative sign shows that the induced voltage acts
in such a wa y as to oppos e the magnetic flux producing
it. Th is is know n as Lenz ’s Law and i t empha sizes the
fact that the direction of current flow in the circuit is
such that the induced magnetic field produced by the
induce d current will oppose th e original magne tic field.
The magn etic fl ux Ψ in Equation 4 is the total magnetic
field B that is passing through the entire surface of the
antenna coil, and found by:
EQUATION 5:
where:
The inner product presentation of two vectors in
Equation 5 suggests that the total magnetic flux ψ that
is passing through the antenna coil is affected by an
orientation of the antenna coils. The inner product of
two vectors becomes maximized when the two vectors
are in the same direction. Therefore, the magnetic flux
that is passing through the tag coil will become
maxim iz ed when the tw o co ils (rea der coil and tag coi l)
are placed in parallel with respect to each other.
FIGURE 4: A BASIC CONFIGURATION OF READER AND TAG ANTENNAS IN AN RFID
APPLICATION
N= num ber of turns in the antenna coil
Ψ= magnetic flux through each turn
VN
dΨ
dt
--------
–=
B = magnetic field given in Equation 3
S= surface area of the coil
• = inner product (
cosine angle between
two ve ctors
) of vectors B and surface
area S
Note: Both magnetic field B and surface S are
vector quantities.
ψB·Sd
∫
=
Tag Coil
V = V0sin(ωt)
Tag
B = B
0
sin(
ω
t)
Reader Coil
I = I
0
sin(
ω
t)
Tuning Circuit
Reader
Electronics
AN678
DS00678B-page 28 1998 Microchip Technology Inc.
From Equations 3, 4, and 5, the induced voltage V0 for
an untuned loop antenna is given by:
EQUATION 6:
where:
If the c oil is tuned (with c apacitor C) to th e frequ ency of
the arrival signal (125 kHz), the output voltage Vo will
rise substantially. The output voltage found in
Equation 6 is multiplied by the loaded Q (Quality
Factor) of the tuned circuit, which can be varied from 5
to 50 in typical low-frequency RFID applications:
EQUATION 7:
where the loaded Q is a measure of the selectivity of
the frequency of the interest. The Q will be defined in
Equations 30, 31, and 37 for general, parallel, and
serial resonant circuit, respectively.
FIGURE 5: ORIENTATION DEPENDEN C Y
OF THE TAG ANTENNA.
The induced voltage developed across the loop
antenna coil is a function of the angle of the arrival sig-
nal. The induced voltage is maximized when the
antenna coil is placed perpendicular to the direction of
the incoming signal where α = 0.
EXAMPLE 1: B-FIELD REQUIREMENT
EXAMPLE 2: NUMBER OF TURNS AND
CURRENT (AMPERE-
TURNS) OF READER COIL
f = frequency of the arrival signal
N= num ber of turns of coil in the loop
S= area of the l oop in square me ters (m2)
Bo= strength of the arrival signal
α= angle of arrival of the signal
Vo2πfNSBoαcos=
Vo2πfoNQSBoαcos=
Tag
B-field
α
Line of axis
(Tag)
The strength of the B-field that is needed to turn on
the tag can be calculated from Equation 7:
EQUATION 8:
where the following parameters are used in the
above calculation:
tag coil siz e = 2 x 3 inches =
38.71 cm2: (credit
card size)
frequency = 125 kHz
number of turns = 100
Q of antenna coil = 15
AC coil voltage
to turn on the tag = 7 V
cos α= 1 (normal directio n,
α= 0).
BoVo
2πfoNQS αcos
------------------------------------=
72.4()
2π()125 kHz()100()15()38.71cm2
()
-------------------------------------------------------------------------------------------=
1.5≈µWb/m2
Assuming that the reader should provide a read
range of 10 inches (25.4 cm) with a tag given in
Example 1, the requirement for the current and
numbe r of t u r n s ( Am pe r e-t u rns ) of a rea de r co il tha t
has an 8 cm radius can be calculated from
Equation 3:
EQUATION 9:
This is an attainable number. If, ho wev er, we wish to
have a read range of 20 inches (50.8 cm), it can be
found that NI increases to 48.5 ampere-turns. At
25.2 inches (64 cm), it exceeds 100 ampere-turns.
NI() 2Bza2r2
+()
µa2
-------------------------------
32⁄
=
21.5 106–
×()0.0820.2542
+()
4π10 7–
×()0.08()
------------------------------------------------------------------------- 32⁄
=
7.04 ampere - turns()=
1998 Microchip Technology Inc. DS00678B-page 29
AN678
For a longer read range, it is instructive to consider
increasing the radius of the coil. For example, by
doubling the radius (16 cm) of the loop, the
ampere-t urns requirem ent f or the same read rang e (10
inches: 25.4 cm) becomes:
EQUATION 10:
At a read range of 20 inches (50.8 cm), the
ampere-turns becomes 13.5 and at 25.2 inches (64
cm), 26.8. Therefore, for a longer read range,
increasing the tag size is often more effective than
incr easing the coi l current. F igure 6 shows th e relation-
ship between the read range and the ampere-turns
(IN).
FIGURE 6: AMPERE-TURNS VS. READ
RANGE FOR AN ACCESS
CONTROL CARD (CREDIT
CARD SIZE)
The optimum radius of loop that requires the minimum
numb er of ampere-turns for a p articular read ra nge can
be found from Equation 3 such as:
EQUATION 11:
where:
By taking derivative with respect to the radius a,
The above equation becomes minimized when:
The above result shows a relationship between the
read range vs. tag size. The optimum radius is found
as:
where:
The above result indicates that the optimum radius of
loop for a reader antenna is 1.414 times the read
range r.
NI 21.5 106–
×()0.1620.252
+()
4π10 7–
×()0.162
()
---------------------------------------------------------------------- 32⁄
=
2.44 (amp er e - tu r n s)=
100
10
1
0.1
0.01
0.001
0.001 0.01 0.1 101
a = 50 cm
a = 20 cm
a = 10 cm
a = 5 cm
a = 2 cm
a = sqrt(2)*r
r (m)
NI for 1.5 µ-Weber/m2
Note: BO = 1.5 µWb/m2 is used.
a= radius of coil
r= read range
NI K a2r2
+()
3
2
---
a2
------------------------
=
K2Bz
µo
---------=
dNI()
da
-------------- K32⁄a2r2
+()
12⁄2a3
()2aa
2r2
+()
32⁄
–
a4
------------------------------------------------------------------------------------------------
=
Ka22r2
–()a2r2
+()
12⁄
a3
------------------------------------------------------
=
a22r2
–0=
a2= r
AN678
DS00678B-page 30 1998 Microchip Technology Inc.
WIRE TYPES AND OHMIC LOSSES
Wire Size and DC Resistance
The diameter of electrical wire is expressed as the
American Wire Gauge (AWG) number. The gauge
number is inversely proportional to diameter and the
diamete r is roughly doub led e very six wire ga uges. The
wire with a smaller diameter has higher DC resistance.
The DC resistance for a conductor with a uniform
cross-sectional area is found by:
EQUATION 12:
where:
Table 1 shows the diameter for bare and
enamel-coated wires, and DC resistance.
AC Resistance of Wire
At DC, charge carriers are evenly distributed through
the entire cross section of a wire. As the frequency
increases, the reactance near the center of the wire
increases. This results in higher impedance to the cur-
rent densi ty in the reg ion. Therefore , the charg e mov es
away from the center of the wire and towards the edge
of the wire. As a result, the current density decreases
in the c enter of the w ire and inc reases ne ar the edge of
the wire. This is called a
skin effect
. The depth into the
conductor at which the current density falls to 1/e, or
37% of its v alue al ong the su rface, is kno wn as the
skin
depth
and is a function of the freque ncy and the perme-
ability and conductivity of the medium. The skin depth
is given by:
EQUATION 13:
where:
EXAMPL E 3:
The wire resistance increases with frequency, and the
resistance due to the skin depth is called an AC
resistance. An approximated formula for the ac resis-
tance is given by:
EQUATION 15:
where:
For copper wire, the loss is approximated by the DC
resistance of the coil, if the wire radius is greater than
cm. At 125 kHz, the critical radius is 0.019
cm. This is equivalent to #26 gauge wire. Therefore, for
minim al lo ss, wir e gau ge num bers of grea ter t han #26
should be a voided if coil Q is to be maximized.
l = total length of the wire
σ= conductivity
S= cross-sectional area
f= frequency
µ= permeability of mat erial
σ= conductivity of the material
RDC l
σ
S
------=Ω()
δ1
πfµ
σ
-----------------=
a= coil radius
The skin depth for a copper wire at 125 kHz can be
calcu la ted as :
EQUATION 14:
δ1
πf4π10 7–
×()5.8 10 7–
×()
--------------------------------------------------------------------=
0.06608
f
-------------------=m()
0.187=mm()
Rac 1
2
σ
πδ
------------- RDC
()
a
2δ
------
=≈Ω()
0.066 f⁄
1998 Microchip Technology Inc. DS00678B-page 31
AN678
TABLE 1: AWG WIRE CHART
Wire
Size
(AWG)
Dia. in
Mils
(bare)
Dia. in
Mils
(coated)
Ohms/
1000 ft.
Cross
Section
(mils)
1 289.3 — 0.126 83690
2 287.6 — 0.156 66360
3 229.4 — 0.197 52620
4 204.3 — 0.249 41740
5 181.9 — 0.313 33090
6 162.0 — 0.395 26240
7 166.3 — 0.498 20820
8 128.5 131.6 0.628 16510
9 114.4 116.3 0.793 13090
10 101.9 106.2 0.999 10380
11 90.7 93.5 1.26 8230
12 80.8 83.3 1.59 6530
13 72.0 74.1 2.00 5180
14 64.1 66.7 2.52 4110
15 57.1 59.5 3.18 3260
16 50.8 52.9 4.02 2580
17 45.3 47.2 5.05 2060
18 40.3 42.4 6.39 1620
19 35.9 37.9 8.05 1290
20 32.0 34.0 10.1 1020
21 28.5 30.2 12.8 812
22 25.3 28.0 16.2 640
23 22.6 24.2 20.3 511
24 20.1 21.6 25.7 404
25 17.9 19.3 32.4 320
Note: 1 mil = 2.54 x 10-3 cm
26 15.9 17.2 41.0 253
27 14.2 15.4 51.4 202
28 12.6 13.8 65.3 159
29 11.3 12.3 81.2 123
30 10.0 11.0 106.0 100
31 8.9 9.9 131 79.2
32 8.0 8.8 162 64.0
33 7.1 7.9 206 50.4
34 6.3 7.0 261 39.7
35 5.6 6.3 331 31.4
36 5.0 5.7 415 25.0
37 4.5 5.1 512 20.2
38 4.0 4.5 648 16.0
39 3.5 4.0 847 12.2
40 3.1 3.5 1080 9.61
41 2.8 3.1 1320 7.84
42 2.5 2.8 1660 6.25
43 2.2 2.5 2140 4.84
44 2.0 2.3 2590 4.00
45 1.76 1.9 3350 3.10
46 1.57 1.7 4210 2.46
47 1.40 1.6 5290 1.96
48 1.24 1.4 6750 1.54
49 1.11 1.3 8420 1.23
50 0.99 1.1 10600 0.98
Wire
Size
(AWG)
Dia. in
Mils
(bare)
Dia. in
Mils
(coated)
Ohms/
1000 ft.
Cross
Section
(mils)
Note: 1 mil = 2.54 x 10-3 cm
AN678
DS00678B-page 32 1998 Microchip Technology Inc.
INDUCTANCE OF VARIOUS
ANTENNA COILS
The electrical current flowing through a conductor
produces a magnetic field. This time-varying magnetic
field is capable of producing a flow of current through
another conductor. This is called inductance. The
inductance L depends on the ph ysical cha racteristics of
the conductor. A coil has more inductance than a
str aight wire of the sa me materi al, and a coil with mo re
turns has more ind uctan ce tha n a coil with fe we r tu rns.
The inductance L of inductor is defined as the ratio of
the total magnetic flux linkage to the current Ι through
the inductor: i.e.,
EQUATION 16:
where:
In a typical RFID antenna coil for 125 kHz, the
inducta nce is often cho sen as a fe w (mH) for a tag and
from a few hundred to a fe w thousand (µH) for a reader .
For a coil antenna with multiple turns, greater
inductance results with closer turns. Therefore, the tag
antenna coil that has to be formed in a limited space
often nee ds a mu lti-la y er windin g to reduce the nu mber
of turns.
The design of the inductor would se em to be a relativ ely
simple matter. However, it is almost impossible to
construct an ideal inductor because:
a) The coil has a finite conductivity that results in
losses, and
b) The distributed capacitance exists between
turns of a coil and between the conductor and
surrounding objects.
The actual inductance is always a combination of
resista nce, inductanc e, an d capac itance . The apparent
inducta nce is the effectiv e inductance at any frequency,
i.e., inductive minus the capacitive effect. Various
formulas are available in literatures for the calculation
of inductance for wires and coils[1, 2]
.
The parameters in the inductor can be measured. For
example, an HP 4285 Precision LCR Meter can
measur e the inductance, res is tan ce, and Q of the coil.
Inductance of a Straight Wire
The inductance of a straight wound wire shown in
Figure 1 is given by:
EQUATION 17:
where:
EXAMPLE 4: CALCULATION OF
INDUCTANCE FOR A
STRAIGHT WIRE
Inductance of a Single Layer Coil
The inductance of a single layer coil shown in Figure 7
can be calculated by:
EQUATION 19:
where:
FIGURE 7: A SINGLE LAYER COIL
N = number of turns
I = current
Ψ = magnetic flux
LNψ
I
--------= (Henry)
l and a= length and radius of wire in cm,
respectively.
a= coil radius (cm)
l= coil length (cm)
N= number of turns
L0.002lloge2l
a
-----3
4
---–
=µH()
The inductance of a wire with 10 feet (304.8 cm)
long and 2 mm diameter is calculated as follows:
EQUATION 18:
L0.002 304.8()
2304.8()
0.1
---------------------
ln 3
4
---
–
=
0.60967 7.965()=
4.855 µH()=
LaN()
2
22.9l25.4a+
--------------------------------=µH()
l
a
Note: Fo r be s t Q of the coil, the length should
be roughly the same as the diameter of
the coil.
1998 Microchip Technology Inc. DS00678B-page 33
AN678
Inductance of a Circular Loop Antenna Coil
with Multilayer
To form a big inductance coil in a limited space, it is
more efficient to use multilayer coils. For this reason, a
typical RFID antenna coil is formed in a planar
multi- tur n str uctu re. Figur e 8 s hows a cro ss sec tion of
the coil. The inductance of a circular r ing antenna coil
is ca lcula ted by an em pirical formula[2]:
EQUATION 20:
where:
FIGURE 8: A CIRCULAR LOOP AIR CORE
ANTENNA COIL WITH
N-TURNS
The number of turns needed for a certain inductance
value is simply obtained from Equation 20 such that:
EQUATION 21:
EXAMPLE 5: EXAMPLE ON NUMBER OF
TURNS
Inductance of a Square Loop Coil with
Multilayer
If N is the number of turns and a is the side of the
square m easured t o the center of the rectang ular cr oss
section that has length b and depth c as shown in
Figure 9 , then[2]:
EQUATION 23:
The formulas for inductance are widely published and
pro vide a reasonab le appro ximation for the relations hip
between inductance and number of turns for a given
physical size[1]-[4]. When building prototype coils, it is
wise to exceed the number of calculated turns by about
10%, an d then remo v e turns to a chie v e reson ance . For
produ cti on c oi ls, it is best to specify an inductance and
tolerance ra ther than a specific number of turns.
FIGURE 9: A SQUARE LOOP ANTENNA
COIL WITH MULTILAYER
a= average radius of the coil in cm
N= num ber of turns
b= winding thickness in cm
h= windi ng height in cm
L0.31 aN()
2
6a9h10b++
----------------------------------=µH()
X
b
a
h
a
b
center of coil
N-Turn Coil
NLµH6a9h10b++()
0.31()a2
--------------------------------------------------=
Equation 21 re su lts i n N = 200 turns for L = 3.8 7 mH
with the following coil geometry:
To form a resonant circuit for 125 kHz, it needs a
capaci tor acr oss the in ducto r. Th e resona nt capaci -
tor can be calcu lated as:
EQUATION 22:
a= 1 inch (2.54 cm)
h= 0.05 cm
b=0.5 cm
C1
2πf()
2L
------------------- 1
4π2
()125 103
×()3.87 10 3–
×()
----------------------------------------------------------------------------==
419=pF()
L0.008aN22.303log10 a
bc+
------------
0.2235bc+
a
------------0.726++
=µH()
(a) Top View (b) Cross Sectional View
b
c
a
N-Turn Coil
a
AN678
DS00678B-page 34 1998 Microchip Technology Inc.
CONFIGURATION OF ANTENNA
COILS
Tag Antenna Coil
An antenna coil for an RFID tag can be configured in
many different ways, depending on the purpose of the
application and the dimensional constraints. A typical
inductance L for the tag coil is a few (mH) for 125 kHz
devices. Fig ur e 10 shows var i ou s con f ig urat i on s of tag
ante nna c oil s. The coil is t ypic all y mad e of a t hin wir e.
The induc tance and the num ber of turns of the coil can
be calculated by the formulas given in the previous sec-
tion. An Inductance Meter is ofte n used to measu re the
induc tan ce of th e coi l. A ty pica l number of tur n s of t he
coil is in the range of 100 turns for 125 kHz and 3~5
turns for 13.56 MHz devices.
F or a longer read range , the antenna coil mus t be tuned
properly to the frequency of interest (i.e., 125 kHz).
Voltage drop acro ss the c oil is ma xi mized by forming a
parallel resonant circuit. The tuning is accomplished
with a resonant capacitor that is connected in parallel
to the coil as shown in Figure 10. The formula for the
resonant capacitor value is given in Equation 22.
FIGURE 10: VARIOUS CONFIGURATIONS OF TAG ANTENNA COIL
Co
a
2a
CoCo
d = 2a
2a
N-turn Coil
b
1998 Microchip Technology Inc. DS00678B-page 35
AN678
Reader Antenna Coil
The inductance for the reader antenna coil is ty pically
in the range of a few hundred to a few thousand
micr o-Henrie s (µH) for lo w fr equenc y appl icati ons . The
reader antenna can be m ade of either a sin gl e c oil th at
is typically forming a series resonant circuit or a double
loop (transformer) antenna coil that forms a parallel
resonant circuit.
The series resonant circuit results in minimum
impedance at the resonance frequency. Therefore, it
draws a maximum current at the resonance frequency.
On the other hand, the parallel resonant circuit results
in maximum impedance at the resonance frequency.
Theref ore, the current beco me s m ini mi z e d at th e res o-
nance frequency. Since the voltage can be stepped up
by forming a double loop (parallel) coil, the parallel
resonant circuit is often used for a system where a
higher voltage signal is required.
Figure 11 shows an example of the transformer loop
antenna. The main loop (secondary) is formed with
several turns of wire on a large frame, with a tuning
capacitor to resonate it to the resonance frequency
(125 kHz). The other loop is called a coupling loop
(pr imary), and it is for med with less than two or three
turns of coil. This loop is placed in a very close
proximity to the main loop, usually (but not necessarily)
on the inside edge and not more than a couple of cen-
timeters away from the main loop. The purpose of this
loop is to couple signals induced from the main loop to
the reader (or vise versa) at a more reasonable
matching impedance.
The coupling (primary) loop provides an impedance
match t o the inpu t/output im pedance of the r eader . Th e
coil is connected to the input/output signal driver in the
reader el ectron ics . The main lo op (se conda ry) must be
tuned to resonate at the resonance frequency and is
not physically connected to the reader electronics.
The coupling loop is usually untuned, but in some
designs, a tuning capacitor C2 is placed in series with
the cou pling loop. Because there a re far fe we r turns on
the coupling loop than the main loop, its inductance is
considerably smaller. As a result, the capacitance to
resonate is usually much larger.
FIGURE 11: A TRANSFORMER LOOP ANTENNA FOR READER
C2
Coupling Coil
(primary coil)
To reader electronics
Main Loop
(secondary coil) C1
AN678
DS00678B-page 36 1998 Microchip Technology Inc.
RESONANCE CIRCUITS, QUALITY
FACTOR Q, AND BANDWIDTH
In RFID applications, the antenna coil is an element of
resonant circuit and the read range of the device is
greatly affected by the performance of the resonant
circuit.
Figures 12 and 13 show typical examples of resonant
circuits formed by an antenna coil and a tuning
capaci tor. The res onanc e frequen cy (fo) of the circuit i s
determined by:
EQUATION 24:
where:
The resonant circuit can be formed either series or
parallel.
The series resonant circuit has a minimum impedance
at the resonance frequency. As a result, maximum
current is available in the circuit. This series resonant
circuit is typically used for the reader antenna.
On the other hand, the parallel resonant circuit has
maximum impedance at the resonance frequency. It
offers minimum current and maximum voltage at the
resonance frequency. This parallel resonant circuit is
used for the tag antenna.
Parallel Resonant Circuit
Figure 12 shows a simple parallel resonant circuit. The
total impedance of the circuit is given by:
EQUATION 25:
where:
The ohmic resistance r of the coil is ignored. The
maximum impedance occurs when the denominator in
the above equation minimized such as:
EQUATION 26:
This is ca lled a resonanc e condition and the res onance
frequency is given by:
EQUATION 27:
By applying Equation 26 into Equation 25, the
impedance at the resonance frequency becomes:
EQUATION 28:
FIGURE 12: PARALLEL RESONANT
CIRCUIT
The R and C in the parallel resonant circuit determine
the bandwidth, B, of the circuit.
EQUATION 29:
L= inductance of antenna coil
C= tuning ca pacitance
fo1
2πLC
------------------=
ω= angular frequency = 2πf
R= load resi stor
Zjω() jωL
1ω2LC–()jωL
R
-------
+
---------------------------------------------= Ω()
ω2LC 1=
fo1
2πLC
------------------=
ZR=
RLC
B1
2πRC
---------------= Hz()
1998 Microchip Technology Inc. DS00678B-page 37
AN678
The quality factor, Q, is defined by various ways such
as:
EQUATION 30:
where:
By applying Equation 27 and Equation 29 into
Equation 30, the loaded Q in the parallel resonant
circuit is:
EQUATION 31:
The Q in parall el resonan t circuit is direct ly proportional
to the load resistor R and also to the square root of the
rati o of capacitance and induct ance in the circuit.
When this parallel resonant circuit is used for the tag
ante nn a ci rc ui t, t h e volt age dr o p a cro ss t he c ircuit can
be obtained by combining Equations 7 and 31,
EQUATION 32:
The above equation indicates that the induced voltage
in the tag coil is inversely proportional to the square
root of the coil induct ance , b ut prop ortional to the num -
ber of turns and surface area of the coil.
The para ll el resonant circuit can be used in the trans-
former loop antenna for a long-range reader as dis-
cussed in "Reader Antenna Coil" (Figure 11). The
v oltage in the sec ondary loop is proportional to the turn
ratio (n2/n1) of the t r a nsf ormer loop. How ever, this high
voltage signal can co rrupt the receivin g signals. For this
reason, a separ ate an tenna i s need ed for rec eiving th e
signal. This receiving antenna circuit should be tuned
to the m od ula tin g s ign al of the tag an d detunne d to the
carrier signal frequency for maximum read range.
Series Resonant Circuit
A simp le se rie s reso nan t circu it is shown in Figur e 13.
The expression for the impedance of the circuit is:
EQUATION 33:
where:
EQUATION 34:
EQUATION 35:
The impedance in Equation 33 becomes minimized
when the reactance component cancelled out each
other such that XL = XC. This is called a resonance
condition. The resonance frequency is same as the
parallel resonant frequency given in Equation 27.
FIGURE 13: SERIES RESONANCE
CIRCUIT
The half power frequency bandwidth is determined by
r and L, and given by:
EQUATION 36:
fo= resonant frequency
B= bandwidth
QEnergy Stored in the System per One Cycle
Energy Dissipated in the System per One Cycle
------------------------------------------------------------------------------------------------------------------=
fo
B
----=
QR
C
L
----=
Vo2πfoNQSBoαcos=
2πfoNR C
L
----
SBoαcos=
r= ohmic resistance of the circuit
Zjω() rjX
LXC
–()+= Ω()
XL2πfoL=Ω()
Xc1
2πfoC
---------------=Ω()
C
EIN L
Eo
125 kHz
r
Br
2πL
----------= Hz()
AN678
DS00678B-page 38 1998 Microchip Technology Inc.
The quality factor, Q, in the series resonant circuit is
given by:
EQUATION 37:
The series circuit forms a voltage divider; the voltage
drops in the coil is given by:
EQUATION 38:
or
EQUATION 39:
EXAMPLE 6: CIRCUIT PARAMETERS.
EXAMPLE 7: CALCULATION OF READ
RANGE
ωL
r
------- 1
ωCr
------------= for unloaded circuit;
1
r
---L
C
---- ; for loaded circuit
Qfo
B
---- ==
VojXL
rjX
LjXc
–+
------------------------------- Vin
=
Vo
Vin
---------XL
r2XLXc
–()
2
+
----------------------------------------------XL
r1XLXc
–
r
---------------------
2
+
----------------------------------------------- Q
1XLXc
–
r
---------------------
2
+
--------------------------------------------== =
If the s eries re sistance of th e circuit is 15 Ω, then the
L and C values form a 125 kHz resonant circuit with
Q = 8 are:
EQUATION 40:
XLQrs120Ω==
LXL
2πf
-------- 120
2π125 kHz()
--------------------------------- 153== = µH()
C1
2πfXL
-----------------1
2π125 kHz()120()
----------------------------------------------- 10.6== = nF()
Let us con sider desig ning a reader an tenna coil w ith
L = 153 µH, diameter = 10 cm, and winding
thickness and height are small compared to the
diameter.
The number of turns for the inductance can be
calculated from Equation 21, resulting in 24 turns.
If the current flow through the coil is 0.5 amperes,
the ampere-turns becomes 12. Therefore, the read
range for this coil will be about 20 cm with a credit
card size tag.
1998 Microchip Technology Inc. DS00678B-page 39
AN678
Q and Bandwidth
Figure 14 shows the approximate frequency bands for
common forms of Amplitude Shift Keying (ASK),
Frequency Shift Keying (FSK), and Phase Shift Keying
(PSK) modulation. For a full recovery of data signal
from the tag, the reader circuit needs a bandwidth that
is at le ast twice the d ata rate . Therefo re, if th e data ra te
is 8 kHz for an ASK signal, the bandwidth must be at
least 16 kHz for a full rec ove ry of the in formation that is
coming from the tag.
The data rate for FSK (÷ 10) signal is 12.5 kHz.
Therefore, a bandwidth of 25 kHz is needed for a full
data reco very.
The Q for this FSK (÷ 10) signal can be obtained from
Equation 30.
EQUATION 41:
For a PSK (÷ 2) signal, the data rate is 62.5 kHz (if the
carrier frequency is 125 kHz) therefore, the reader
circuit needs 125 kHz of bandwidth. The Q in this case
is 1, and consequently the circuit becomes
Q-independent.
This problem may be solved by separating the
transmitting and receiving coils. The transmitting coil
can be designed with higher Q and the receiving coil
with lower Q.
Limitation on Q
When designing a reader antenna circuit, the
temptation is to design a coil with very high Q. There
are three important limitations to this approach.
a) Very high voltages can cause insulation
breakdown in either the coil or resonant
capacitor.
F or example, a 1 ampere of current flow in a 2 mH
coil will produce a voltage drop of 1500 VPP. Such
voltages are easy to obtain but difficult to isolate.
In addition, in the case of single coil reader
designs, recovery of the return signal from the tag
must be accomplished in the presence of these
high voltages.
b) Tuning becomes critical.
To implement a high Q antenna circuit, high volt-
age components with a close tolerance and high
stability would have to be used. Such parts are
generally expensive and difficult to obtain.
c) As the Q of the cir cuit ge ts high er, the ampli tude
of the return signal relative to the power of the
carrier gets proportionally smaller complicating
its recover y by the reader circuit.
FIGURE 14: Q FACTOR VS. MODULATION SIGNALS
Qfo
B
----125 kHz
25 kHz
--------------------==
5=
35
30
25
20
15
10
5
050 75 100 125 150 175 200
Q = 30
Q = 14
Q = 8
Q =5
ASK FSK
÷8,10
FSK
÷8,10
PSK
÷2
PSK
÷2
AN678
DS00678B-page 40 1998 Microchip Technology Inc.
Tuning Method
The circuit must be tuned to the resonance frequency
for a ma ximum p erformance (re ad range) of the de vice.
Two examples of tuning the circuit are as follows:
• Voltage Measurement Method:
a) Set up a voltage signal source at the
resonance frequency (125 kHz)
b) Connect a voltage signal source across the
resonant circuit.
c) Connect an Oscilloscope across the
resonant circuit.
d) Tune the capacitor or the coil while
observing the signal amplitude on the
Oscilloscope.
e) Stop the tuning at the maximum voltage.
• S-parameter or Impedance Measurement
Method using Network Analyzer:
a) Set up an S-Parameter Test Set (Network
Analyzer) for S11 measurement, and do a
calibration.
b) Measure the S11 for the resonant circuit.
c) Reflection impedance or reflection
admittance can be measured instead of the
S11.
d) Tune the capacitor or the coil until a
maximum null (S11) occurs at the
resonance frequency, fo. For the impedance
measurement, the maximum peak will occur
for the parallel resonant circuit, and
minimum peak for the series resonant
circuit.
FIGURE 15: VOLTAGE VS. FREQUENCY FOR RESONANT CIRCUIT
FIGURE 16: FREQUENCY RESPONSES FOR RESONANT CIRCUIT
f
fo
V
(a) (b) (c)
S11
f
fofo
Z
ffo
Z
f
Note 1: (a) S11 Response , (b) Imped ance Respo nse for a P a rallel R esonan t Circuit, and (c )
Impedance Response for a Series Resonant Circuit.
2: In (a), the null at the resonance frequency represents a minimum input reflection at
the resona nce frequ ency. This mean s the ci rcuit abs orbs the s ignal at the frequen cy
while other frequencies are reflected back. In (b), the im pedance curve has a peak
at the re sonan ce freque ncy. This is beca use the p ar allel reso nant c ircui t has a m ax-
imum impedance at the resonance frequency. (c) shows a response for the ser ies
resonant circuit. Since the series resonant circuit has a minimum impedance at the
resonance frequency, a minimum peak occurs at the resonance frequency.
1998 Microchip Technology Inc. DS00678B-page 41
AN678
READ RANGE OF RFID DEVICES
Read range is defined as a maximum communication
distance between the reader and tag. The read range
of typical passive RFID products varies from about
1 inch to 1 meter, depending on system configuration.
The read range of an RFID device is, in general,
affected by the following parameters:
a) Operating frequency and performance of
antenna coils
b) Q of antenna and tuning circuit
c) Antenna orientation
d) Excitation current and voltage
e) Sensitivity of receiver
f) Coding (or modulation) and decoding (or
demodulation) algorithm
g) Number of data bits and detection
(interpretation) algorithm
h) Condition of operating environment (metallic,
electrical noise), etc.
With a giv e n opera ting freq uency, the abo ve conditi ons
(a – c) are related to the antenna configuration and
tuning cir cui t. The cond itions (d – e) are determined by
a circuit topology of the reader. The condition (f) is
called the communication protocol of the device, and
(g) is rela ted to a firmw ar e pro g r am for d ata interpreta-
tion.
Assuming the device is operating under a given
condition, the read range of the device is largely
affected by the performance of the antenna coil. It is
always true that a longer read range is expected with
the large r s ize of the ante nna . Fi gure s 17 and 18 sh o w
typical examples of the read range of various passive
RFID devices.
FIGURE 17: READ RANGE VS. TAG SIZE FOR PROXIMITY APPLICATIONS
FIGURE 18: READ RANGE VS. TAG SIZE FOR LONG RANGE APPLICATIONS
Proximity Reader
Antenna
Tag
Tag
Tag
Tag
1 inch
2 inches
3 ~ 4 inches
4 ~ 5 inches
0.5" diameter
1" diameter
2" diameter
3.37" x 2.125"
(Credit Card Type: ISO Card)
(4" x 3")
(16" x 32")
Long Range
0.5" diameter
4 ~ 5 inches
8 ~ 12 inches
18 ~ 22 inches
27 ~ 32 inches
Reader Antenna 2" diameter
3.37" x 2.125"
Tag
Tag
Tag
Tag
(Credit Card Type: ISO Card)
1" diameter
AN678
DS00678B-page 42 1998 Microchip Technology Inc.
REFERENCES
1. Frederick W. Grover, Inductance Calculations:
Working Formulas and Tables, Dover
Publications, Inc., New York, NY., 1946.
2. Keith Henry, Editor, Radio Engineering
Handbook, McGraw-Hill Book Company, New
York, NY., 1963.
3. V. G. Welsby, The Theory and Design of
Inductance Coils, John Wiley and Sons, Inc.,
1960.
4. Ja mes K. Hardy, High Fre quency Cir cuit Design,
Reston Publishing Company, Inc., Reston,
Virginia, 1975.
1998 Microchip Technology Inc. DS51137B-page 43
MmicroID™ 125 kHz DESIGN GUIDE
1.0 INTRODUCTION
This app licat ion not e is written as a re ference guide for
FSK reader designers. Microchip Technology Inc.
provides basic reader electronics circuitry for the
MCRF200 customers as a part of this design guide.
The circ uit i s de si gne d fo r a read ra nge of 3 ~ 5 inc he s
with a n a c cess co nt ro l ca r d. T h e m ic ro ID FSK Reader
(demo unit), which is built based on the FSK reference
design, is available in the microID Designers Kit
(DV103001). The circuit can be modified for longer
read r ange or other appl ications with the MCRF200 . An
electronic copy of the FSK microID PICmicro® source
code is available upon request.
2.0 READER CIRCUITS
The RFID read er consi sts of tr an smitting an d receiv ing
sections. It transmits a carrier signal, receives the
backscattering signal, and performs data processing.
The reader also communicates with an external host
computer. A basic block diagram of the typical RFID
reader is shown in Figure 2-1.
FIGURE 2-1: BLOCK DIAGRAM OF TYPICAL RFID READER FOR FSK SIGNAL (125 kHz)
(4 MHz Crystal Oscillator) Carrier Signal Amplifier
(Power Driver)
Env elope Detector
Filter, Amplifier,
and Pulse Shaping
Interface with
Host Computer
Transmitting Section
Antenna Coil
CLK
To Host Computer
Serial Interface (RS-232)
125 kHz
Time Base Signal Generator
Microcontroller
Data Decoding
Receiving Section
÷ 32
FSK Reader Refere nce Design
PICmicro is a registered trademark of Microchip Technology Inc.
microID™ 125
k
Hz Design Guide
DS51137B-page 44 1998 Microchip Technology Inc.
2.1 Transmitting Section
The tr ansmitt ing se ction co ntains c ircui tr y for a ca rrie r
signal (125 kHz), power amplifiers, and a tuned
antenna coil.
The 125 kHz carrier signal is typically generated by
dividing a 4 MHz (4 MHz/32 = 125 kHz) crystal
osci lla tor si gna l. The signa l is am plif ie d befor e it is fed
into the antenna tunin g circuit. A com plementary pow er
amplifier circuit is typically used to boost the
transmitting signal level.
An antenna impedance tuning circuit consisting of
capacitors is used to maximize the signal level at the
carrier frequency. This tuning circuit is also needed to
form an exact LC resonant circuit for the carrier signal.
The tuning compensates the variations in the
component values and the perturbation of coil
inductance due to environment effect. A design guide
for the antenna coil is given in
AN678, RFID Coil
Design,
page 25.
2.1.1 L IMITS ON TRANSMITTING SIGN AL LE VEL
(FCC PART 15) IN THE USA
Each country limits the signal strength of the RF wave
that is intentionally radiated by a device. In the USA, the
signal strength of the carrier signal (125 kHz) radiating
from the antenna coil must comply with the FCC
(Federal Communications Commission) part 15
regulation. The signal level is specified by the 47 CFR
Part 15.209a of the federal regulation. For a 125 kHz
signal, the FCC limits the signal level to 19.2 µv per
meter, or 25.66 dBµV (i .e ., 20 l og(19.2) = 25.66 dBµV),
at 300 meters away from the antenna. For a close
distance measurement, an extrapolation rule (40 dB
per decade) is applied (Part 15.31.f.2). For example,
the signal le v el at 30 meters aw a y from the de vice must
not exceed:
25.66 dBµV + 40 dBµV = 65.66 dBµV
2.2 Receiving Section
The receiving section consists of an antenna coil,
demodulator, filters, amplifiers, and microcontroller. In
applic ations for clo se pro ximity read range, a single coi l
is often used for both transmitting and receiving. For
long read-range applications, however, separated
antennas may be used. More details on the antenna
coil are given in
AN678, RFID Coil Design,
page 25.
In the FSK communication protocol, a ‘0’ and a ‘1’ are
represented by two different frequencies. In the
MCRF200, a ‘0’ and a ‘1’ are represented by Fc/8 and
Fc/10, respectively. Fc is the carrier frequency. The
MCRF200 sends this FSK signal to the reader by an
amplitude modulation of the carrier signal.
The FSK reader needs two steps for a full recover y of
the data. The first step is demodulating the
bac ksc attering si gnal, and th e sec ond s tep is detec ting
the frequency (or period) of the demodulation signal.
The demodulation is accomplished by detecting the
envelope of the carrier signal. A half-wave
capacitor-filtered rectifier circuit is used for the
demodulation process. A diode detects the peak
voltage of the back scattering signal. The voltage is then
fed into an RC charging/discharging circuit. The RC
time constant must be small enough to allow the
v oltage acro ss C to fall fast enough to keep in step with
the envelope. However, the time constant must not be
so small as to introduce excessive ripple. The
demodu lated sign al mus t then pas s through a f ilter and
signal shaping circuit before it is fed to the microcon-
troller. The microcont roller performs data deco ding and
communicates with the host computer through an
RS-232 or other serial interface protocols.
1998 Microchip Technology Inc. DS51137B-page 45
microID™ 125
k
Hz Design Guide
3.0 microID FSK READER
The electronic circuitry for an FSK reader is shown in
Figure 3-1. The reader needs +9 VDC power supply.
The 125 kH z ca rrier sign al i s ge nerated by div idi ng th e
4 MHz time base signal that is generated by a crystal
oscill ator . A 16-st age binary ripple coun ter (74HC406 0)
is used for this purpose. The 74HC4060 also provides
a clock signal for the PIC16C84 microcontroller. The
125 kH z sign al is pas sed to an R F chok e (L 1) and fil ter
befo re i t is fed int o a p ower am pl ifi er th at i s fo r me d by
a pair of complementary bipolar transistors (Q2 and
Q3).
For long read-range applications, this power amplifier
circuit can be modifi ed. Power M OSFETs may be used
instead of the bipolar transistors (2N2222). These
power MOSFETs can be driven by +24 VDC power
supply. A push-pull predriver can be added at the front
of the complementary circuit. This modification will
enhance the signal level of the carrier signal.
The reader circuit uses a single coil for both
transmitting and receiving signals. An antenna coil
(L2: 1.62 mH) and a resonant capacitor (C2: 1000 pF)
forms a seri es resonant c ircuit for a 125 kHz resonance
frequency. Si nce the C2 is grounded, the carrier signal
(125 kHz) is filtered out to ground after passing the
antenna coil. The circuit provides a minimum imped-
ance at the resonance frequency. This results in
maximizing the antenna current, and therefore, the
magnetic field strength is maximized.
L2, C15, D7, and the other bottom parts in the circuit
form a signal rec eivin g sect ion. The v ol tage drop in the
antenna coil is a summation (superposition) of
tran smitting s ignal and backsca ttering signal. The D7 is
a demodulator which detects the envelope of the
backscattering signal. The FSK signal waveforms are
shown in Figure 3-1.
D7 and C1 9 form a half-w a v e cap acitor-f iltered rectifi er
circuit. The detected envelope signal is charged into
the C19. R21 provides a discharge path for the voltage
charged in the C19. This voltage passes active filters
(U8) and the pulse shapin g circuitry (U8) before it is fe d
into the PIC16C84 for data processing.
The PIC16C8 4 microcontrol ler performs data decodin g
and communicates with the host computer via an
RS-232 serial interface.
FIGURE 3-1: SIGNAL WAV EFORM FOR FSK PROTOC OL (Fc = 125 KHZ)
1 23456 78910
ô í÷ û øù î 12345678910
ôí ÷ûøù î 123
Fc/10 = 12.5 kHz Fc/8 =
15.625 kHz
(‘1’) (‘0’) (‘1’) (‘0’)
80 µsec 64 µsec 80 µsec 64 µsec
Transmitting Signal
Data Signal
Backscattering
Signal in Receiver
Coil
Output Signal of
Envelop Detector
Signal
Detected Signal
after Pulse Shaping
Circuit
microID™ 125
k
Hz Design Guide
DS51137B-page 46 1998 Microchip Technology Inc.
4.0 FSK READER SCHEMATIC
PIC16C84
1998 Microchip Technology Inc. DS51137B-page 47
microID™ 125
k
Hz Design Guide
5.0 FSK READER BILL OF MATERIALS
Item # Qty Part # Reference
Designator Part Description Manufacturer V endor Vendor Part #
1 1 110-93-318-41-001 xU5 SOCKET, 18P OPEN
FRAME COLLET
(0.300)
MILL-MAX DIGIKEY ED3318-ND
2 1 DE9S-FRS P2 CONN, D-SUB 9P
RECPT RT ANGLE SPC
TECHNOLOGY
3 1 DJ005B P1 JACK, POWER,
2.5 mm DC
PC MOUNT
LZR
ELECTRONICS
4 1 PKM22EPP -4001 SP1 BUZZER, PIEZO,
4kHz, 3-20V MURATA
5 2 D220J20COGHAAAC C2, C3 CAP, 22 pF CER DISK
RAD COG 100V PHILIPS DIGIKEY 1330PH-ND
6 6 ECQ-P6102JU C7, C8, C10,
C14, C16,
C18
CAP, 0.001 uF
POLYPROPYLENE
630V
PHILIPS DIGIKEY P3497-ND
7 2 2222 370 52102 C15, C17 CAP, 0.001 uF METAL
FILM, 5%, RAD, 400V PHILIPS DIGIKEY 3001PH-ND
8 1 ECU-S2A182JCB C9 CAP, 1800 pF
MONOLITH CERM,
5%, RAD, 100V
PHILIPS DIGIKEY P4864-ND
9 1 2222 370 52222 C19 CAP, 0.0022 UF 400V
5% MF BOX PHILIPS DIGIKEY 3003PH-ND
10 1 ECU-S1H682JCB C12 CAP, 6800 pF 50V
CERAMIC MONO 5% PANASONIC DIGIKEY P4946-ND
11 2 ECQ-E1104KF C4, C11 CAP, 0.1UF 100VDC
10% RAD METAL
POL Y CAP
PANASONIC DIGIKEY EF1104-ND
12 3 ECS-F1CE106K C5, C6, C13 CAP, TANT, 10uF, 16V PANASONIC DIGIKEY P2038-ND
13 1 ECS-F1AE107 C1 CAP, 100 UFD @
10VDC 20%
TANTA LUM CAP
PANASONIC DIGIKEY P2032-ND
14 6 1N4148 D1-D6 DIODE, GENERAL
PURPOSE, 1N4148
(DO-35)
DIODES INC. DIGIKEY 1N4148D ITR-
ND
15 1 1N4936 D7 DIODE, 1A 400V
FAST-RECOVERY
RECTIFIER
DIODES INC DIGIKEY 1N4936CT-ND
16 1 -SPAR E- LED1 -SPARE- LOCATION
DO NOT INSTALL
17 1 78F102J L1 INDUCTOR, 1000 µH,
COATED JW MILLER DIGIKEY M7849-ND
18 1 MCT0003-001 L2 INDUCTOR, 1.62 mH CORNELL DUBI-
LIER
19 3 2N2907A Q1, Q3, Q4 TRANSISTOR, PNP,
2N2907A, TO-92 MOTOROLA
20 1 2N2222A Q2 TRANSISTOR, NPN,
2N2222A, TO-92 MOTOROLA ALLIED 2N2222A
21 2 5043CX10R0J R10, R13 RES, CF 10 OHM
1/4W 5% PHILLIPS
22 1 82E CR-1/4W-B 5% R11 RES, CF 82 OHM
1/4W 5% YAGEO DIGIKEY 82QBK-ND
23 2 5043CX100R0J R18, R21 RE S, CF 100 OHM
1/4W 5% PHILLIPS
24 3 5043CX330R0J R4, R14, R17 RES, CF 330 OHM
1/4W 5% PHILLIPS
microID™ 125
k
Hz Design Guide
DS51137B-page 48 1998 Microchip Technology Inc.
25 1 5043CX470R0J R7 RE S, CF 470 OHM
5% 1/4W PHILLIPS
26 1 1K8 CR-1/4W-B 5% R3 RES, CF 1.8K OHM
1/4W 5% YAGEO DIGIKEY 1.8KQBK-ND
27 1 1K82 MF-1/4W-B 1% R12 RES, MF 1.82K OHM
1/4W 1% YAGEO DIGIKEY 1.82KXBK-ND
28 1 2K67 MF-1/4W-B 1% R15 RES, 2.67K OHM
1/4W 1% MF YAGEO DIGIKEY 2.67KXBK-ND
29 1 3K3 CR-1/4W-B 5% R2 RES, CF 3.3K OHM
1/4W 5% YAGEO DIGIKEY 3.3KQBK-ND
30 4 10K CR-1/4W-B 5% R1, R26, R27,
R28 RES, CF 10K OHM
1/4W 5% YAGEO DIGIKEY 10KQBK-ND
31 3 5043ED10K00F R16, R29,
R30 RES, MF 10K
1/4W 1% PHILLIPS
32 2 12K CR-1/4W-B 5% R20, R25 RES, CF 12K OHM
1/4W 5% YAGEO DIGIKEY 12KQBK-ND
33 1 16K5 MF-1/4W-B 1% R22 RES, MF 16.5K OHM
1/4W 1% YAGEO DIGIKEY 16.5KXBK-ND
34 1 22K CR-1/4W-B 5% R6 RES, CF 22K OHM
1/4W 5% YAGEO DIGIKEY 22KQBK-ND
35 1 47K5 MF-1/4W-B 1% R19 RES, MF 47.5K OHM
1/4W 1% YAGEO DIGIKEY 47.5KXBK-ND
36 1 82K5 MF-1/4W-B 1% R23 RES, 82.5K OHM
1/4W 1% MF YAGEO DIGIKEY 82.5KXBK-ND
37 1 5043CX100K0J R9 RES, CF 100K
5% 1/4W PHILLIPS
38 2 1M0 CR-1/4W-B 5% R5, R24 RES, CF 1.0M OHM
1/4W 5% YAGEO DIGIKEY 1.0MQBK-ND
39 1 390K CR-1/4W-B 5% R31 RES, 390K OHM
1/4W 5% CF YAGEO DIGIKEY 390KQBK-ND
40 1 LM78M12Ct U1 IC, REG 12V 3 TERM
POS (TO-220) NATIONAL DIGIKEY LM78M12CT-
ND
41 1 LM78L05ACZ U2 IC, REG, +5V 0.1A
TO-92 NATIONAL DIGIKEY LM78L05ACZ-
ND
42 1 MM74HC04N U3 IC, HEX INVERTER
14P DIP FAIRCHILD
SEMICONDUC-
TOR
DIGIKEY MM74HC04N-
ND
43 1 MM74HC4060N U4 IC , 14 ST A GE BINARY
COUNTER, 16P DIP FA IR CHILD
SEMICONDUC-
TOR
DIGIKEY MM74HC4060N
-ND
44 1 PIC16C84/P U5 IC, PIC16C84
PLASTIC, 14P DIP MICROCHIP
45 1 CD4017BCN U6 IC, DECADE
COUNTER FAIRCHILD DIGIKEY CD4017BCN-
ND
46 1 MM74HC74AN U7 IC, DUAL D TYPE
FLIP FLOP 14P DIP FAIRCHILD DIGIKEY MM74HC74AN-
ND
47 1 TL084CN U8 IC, QUAD OP AMP,
14P DIP SGS THO M P-
SON MOUSER 511-TL084CN
48 1 EFO-EC4004A4 Y1 RESONATOR,
4.00MHZ CERAMIC
W/CAP
PANASONIC DIGIKEY PX400-ND
Item # Qty Part # Reference
Designator Part Description Manufacturer V endor Vendor Part #
1998 Microchip Technology Inc. DS51137B-page 49
microID™ 125
k
Hz Design Guide
6.0 FSK SOURCE CODE FOR THE PICmicro® MCU
The following source code is for the PIC16C84 microcontroller used in the FSK reader electronics.
; #=#=#=#=#=#=#=#=#=#=#= PROJECT Microchip FSK Reader =#=#=#=#=#=#=#=#=#=#=#
;
; PIC16C84 running at 4MHz, Ti=1us
; ///////////////////////////////////////////////////////////////////////////
; Revision history
; ///////////////////////////////////////////////////////////////////////////
;
; Ver Date Comment
;
; 0.01 29 Dec 97 Copied from MChip\Reader\FSK
; 0.03 28 Jan 98 TRANSMIT TAB (h’09’) REGULARLY
; 20 Aug 98 Modified to correct FSK comments
;
; Tbit=50Tcy=400Ti
; Ttag=96Tbit
; Header=h’802A’
;
processor pic16c84
#include “p16c84.inc”
__config b’11111111101001’
; Code Protect on, power-up timer on, WDT off, XT oscillator
#define _CARRY STATUS,0
#define _ZERO STATUS,2
#define _TO STATUS,4
#define _RP0 STATUS,5
#define _BUZZ1 PORTA,0
#define _BUZZ2 PORTA,1
#define _RS232TX PORTA,2
#define _RS232RX PORTA,3
#define _T0CKI PORTA,4
StartPORTA = b’01100’
StartTRISA = b’11000’
BeepPort = PORTA
Beep0 = StartPORTA
Beep1 = StartPORTA | b’00001’
Beep2 = StartPORTA | b’00010’
#define _DATA_IN PORTB,0
#define _UNUSED1 PORTB,1
#define _LED1 PORTB,2
#define _LED2 PORTB,3
#define _UNUSED2 PORTB,4
#define _UNUSED3 PORTB,5
#define _UNUSED4 PORTB,6
#define _UNUSED5 PORTB,7
StartPORTB = b’00000000’
StartTRISB = b’00000001’
StartOPTION = b’00001111’ ; TMR0 internal, prescaler off
BO3 = h’0C’
DelayReg = h’0C’
BitCtr = h’0D’
BeepCtrHi = h’0D’
TxByte = h’0E’
BeepCtrLo = h’0E’
Buffer0 = h’10’ ; --- IMMOBILE --- IMMOBILE --- IMMOBILE --- IMMOBILE
microID™ 125
k
Hz Design Guide
DS51137B-page 50 1998 Microchip Technology Inc.
Buffer1 = h’11’ ; |
Buffer2 = h’12’ ; |
Buffer3 = h’13’ ; |
Buffer4 = h’14’ ; |
Buffer5 = h’15’ ; |
Buffer6 = h’16’ ; |
Buffer7 = h’17’ ; |
Buffer8 = h’18’ ; |
Buffer9 = h’19’ ; |
BufferA = h’1A’ ; |
BufferB = h’1B’ ; |
;BufferC = h’1C’ ; |
;BufferD = h’1D’ ; |
;BufferE = h’1E’ ; |
;BufferF = h’1F’ ; |
Old0 = h’20’ ; |
Old1 = h’21’ ; |
Old2 = h’22’ ; |
Old3 = h’23’ ; |
Old4 = h’24’ ; |
Old5 = h’25’ ; |
Old6 = h’26’ ; |
Old7 = h’27’ ; |
Old8 = h’28’ ; |
Old9 = h’29’ ; |
OldA = h’2A’ ; |
OldB = h’2B’ ; |
;OldC = h’2C’ ; |
;OldD = h’2D’ ; |
;OldE = h’2E’ ; |
;OldF = h’2F’ ; |
SKIP macro
BTFSC PCLATH,7
endm
org h’0000’ ; *#*#*#* RESET VECTOR *#*#*#*
CLRF PCLATH
CLRF INTCON
CLRF STATUS
GOTO RESET_A
org h’0004’ ; *#*#*#* INTERRUPT VECTOR *#*#*#*
CLRF PCLATH
CLRF INTCON
CLRF STATUS
GOTO RESET_A
; ***** Subroutines, Page 0
Delay07 ;[0] Delay 7Ti
NOP ; |
Delay06 ;[0] Delay 6Ti
NOP ; |
Delay05 ;[0] Delay 5Ti
NOP ; |
Delay04 ;[0] Delay 4Ti
RETLW 0 ; |
RS232CR ;[1] Transmit CR on RS232
MOVLW d’13’ ; |
GOTO RS232TxW ; |
RS232TxDigit ;[1] Transmit LSnybble of W on RS232
ANDLW h’0F’ ; |
MOVWF TxByte ; |
MOVLW h’0A’ ; |
1998 Microchip Technology Inc. DS51137B-page 51
microID™ 125
k
Hz Design Guide
SUBWF TxByte,W ; |
BTFSS _CARRY ; |
GOTO DigitLT10 ; |
DigitGE10 ; |
MOVLW ‘A’-’0’-h’0A’ ; |
ADDWF TxByte,f ; |
DigitLT10 ; |
MOVLW ‘0’ ; |
ADDWF TxByte,W ; |
RS232TxW ;[1] Transmit W on RS232 at 9615 baud
MOVWF TxByte ; | TxByte=W
RS232Tx ;[1] Transmit TxByte - 104us = 9615.4 baud
BSF _RS232TX ; | Stop bit
MOVLW d’35’ ; | |
MOVLW DelayReg ; | |
RS232TxD1 ; | |
DECFSZ DelayReg,f ; | |
GOTO RS232TxD1 ; | |
BCF _RS232TX ; | Start bit
NOP ; | |
MOVLW d’32’ ; | |
MOVWF DelayReg ; | |
RS232TxD2 ; | |
DECFSZ DelayReg,f ; | |
GOTO RS232TxD2 ; | |
CLRF BitCtr ; | BitCtr=#8
BSF BitCtr,3 ; | |
RS232TxL1 ; | {% -4Ti
BTFSC TxByte,0 ; | Transmit TxByte.0, RR TxByte
GOTO RS232TxBit1 ; | |
NOP ; | |
RS232TxBit0 ; | |
BCF _RS232TX ; | |
BCF _CARRY ; | |
GOTO RS232TxBitDone ; | |
RS232TxBit1 ; | |
BSF _RS232TX ; | |
BSF _CARRY ; | |
GOTO RS232TxBitDone ; | |
RS232TxBitDone ; | |
RRF TxByte,f ; | |% 4Ti
MOVLW d’30’ ; | delay 1 bit
MOVWF DelayReg ; | |
GOTO RS232TxD3 ; | |
RS232TxD3 ; | |
DECFSZ DelayReg,f ; | |
GOTO RS232TxD3 ; | |
DECFSZ BitCtr,f ; | DEC BitCtr
GOTO RS232TxL1 ; | } until (BitCtr==#0)
CALL Delay04 ; | delay
BSF _RS232TX ; | stop bit
RETLW 0 ; end
; ***** End of subroutines, Page 0
RESET_A
CLRWDT
; Initialise registers
CLRF STATUS ; | Access register page 0
CLRF FSR ; | FSR=#0
MOVLW StartPORTA ; | Initialise PORT and TRIS registers
MOVWF PORTA ; | |
MOVLW StartPORTB ; | |
MOVWF PORTB ; | |
BSF _RP0 ;^| |
MOVLW StartTRISA ;^| |
microID™ 125
k
Hz Design Guide
DS51137B-page 52 1998 Microchip Technology Inc.
MOVWF TRISA ;^| |
MOVLW StartTRISB ;^| |
MOVWF TRISB ;^| |
MOVLW StartOPTION ;^| Initialise OPTION register
MOVWF OPTION_REG ;^| |
BCF _RP0 ; | |
CLRF Old0 ; | Clear Old buffer
CLRF Old1 ; | |
CLRF Old2 ; | |
CLRF Old3 ; | |
CLRF Old4 ; | |
CLRF Old5 ; | |
CLRF Old6 ; | |
CLRF Old7 ; | |
CLRF Old8 ; | |
CLRF Old9 ; | |
CLRF OldA ; | |
CLRF OldB ; | |
BigLoop1
;303-581-1041
BSF _LED1 ; LEDs “reading”
CALL Delay07 ; |
BCF _LED2 ; |
MOVLW h’09’ ; Transmit TAB regularly
CALL RS232TxW ; |
MOVLW d’96’ ; set BitCtr
MOVWF BitCtr ; |
GetEdge ; Get an edge on _DATA_IN
BTFSC _DATA_IN ; |
GOTO PreSync_H ; |
NOP ; |
PreSync_L ; |
BTFSC _DATA_IN ; |
GOTO PreSync_H ; |
BTFSC _DATA_IN ; |
GOTO PreSync_H ; |
DoSync_L ; |
CLRWDT ; |
BTFSS _DATA_IN ; |
GOTO DoSync_L ; |
BTFSS _DATA_IN ; |
GOTO DoSync_L ; |
GOTO Sync_Done ; |
; |
PreSync_H ; |
BTFSS _DATA_IN ; |
GOTO PreSync_L ; |
BTFSS _DATA_IN ; |
GOTO PreSync_L ; |
DoSync_H ; |
CLRWDT ; |
BTFSC _DATA_IN ; |
GOTO DoSync_H ; |
BTFSC _DATA_IN ; |
GOTO DoSync_H ; |
GOTO Sync_Done ; |
Sync_Done ; |% 6 to (+4) from edge, say 8 from edge
;% -192Ti from sample
MOVLW d’62’
MOVWF DelayReg
;% -190Ti from sample
ReadBit ; {% -4-DelayReg*3 Ti from sample
GOTO ReadBitD1 ; delay
ReadBitD1 ; |
DECFSZ DelayReg,f ; |
1998 Microchip Technology Inc. DS51137B-page 53
microID™ 125
k
Hz Design Guide
GOTO ReadBitD1 ; |
CLRF BO3 ; BO3.1=_DATA_IN
BTFSC _DATA_IN ; |
INCF BO3,f ; |% effective sample time
BTFSC _DATA_IN ; |
INCF BO3,f ; |
BTFSC _DATA_IN ; |
INCF BO3,f ; |
BCF _CARRY ; _CARRY=BO3.1
BTFSC BO3,1 ; |
BSF _CARRY ; |
RLF Buffer0,f ; roll in _CARRY
RLF Buffer1,f ; |
RLF Buffer2,f ; |
RLF Buffer3,f ; |
RLF Buffer4,f ; |
RLF Buffer5,f ; |
RLF Buffer6,f ; |
RLF Buffer7,f ; |
RLF Buffer8,f ; |
RLF Buffer9,f ; |
RLF BufferA,f ; |
RLF BufferB,f ; |
; % 19Ti from sample = -381Ti from sample
MOVLW d’124’ ; set bit delay
MOVWF DelayReg ; |% -379Ti from sample
;% -7-DelayReg*3 Ti from sample
DECFSZ BitCtr,f ; DEC BitCtr
GOTO ReadBit ; } until (BitCtr==#0)
HeadSearch
MOVLW d’96’ ; set BitCtr
MOVWF BitCtr ; |
HeadSearchL1 ; {
MOVLW h’80’ ; if (header found)
XORWF BufferB,W ; |
BTFSS _ZERO ; |
GOTO NotHead0 ; |
MOVLW h’2A’ ; |
XORWF BufferA,W ; |
BTFSS _ZERO ; |
GOTO NotHead0 ; {
GOTO HeadFound ; goto HeadFound
NotHead0 ; }
RLF Buffer0,f ; ROL Buffer
RLF Buffer1,f ; |
RLF Buffer2,f ; |
RLF Buffer3,f ; |
RLF Buffer4,f ; |
RLF Buffer5,f ; |
RLF Buffer6,f ; |
RLF Buffer7,f ; |
RLF Buffer8,f ; |
RLF Buffer9,f ; |
RLF BufferA,f ; |
RLF BufferB,f ; |
BCF Buffer0,0 ; |
BTFSC _CARRY ; |
BSF Buffer0,0 ; |
DECFSZ BitCtr,f ; DEC BitCtr
GOTO HeadSearchL1 ; } until (BitCtr==#0)
GOTO BigLoop1 ; goto BigLoop1
HeadFound
CheckSame
microID™ 125
k
Hz Design Guide
DS51137B-page 54 1998 Microchip Technology Inc.
MOVF Buffer0,W
XORWF Old0,W
BTFSS _ZERO
GOTO NotSame
MOVF Buffer1,W
XORWF Old1,W
BTFSS _ZERO
GOTO NotSame
MOVF Buffer2,W
XORWF Old2,W
BTFSS _ZERO
GOTO NotSame
MOVF Buffer3,W
XORWF Old3,W
BTFSS _ZERO
GOTO NotSame
MOVF Buffer4,W
XORWF Old4,W
BTFSS _ZERO
GOTO NotSame
MOVF Buffer5,W
XORWF Old5,W
BTFSS _ZERO
GOTO NotSame
MOVF Buffer6,W
XORWF Old6,W
BTFSS _ZERO
GOTO NotSame
MOVF Buffer7,W
XORWF Old7,W
BTFSS _ZERO
GOTO NotSame
MOVF Buffer8,W
XORWF Old8,W
BTFSS _ZERO
GOTO NotSame
MOVF Buffer9,W
XORWF Old9,W
BTFSS _ZERO
GOTO NotSame
MOVF BufferA,W
XORWF OldA,W
BTFSS _ZERO
GOTO NotSame
MOVF BufferB,W
XORWF OldB,W
BTFSS _ZERO
GOTO NotSame
GOTO Same
NotSame
MOVF Buffer0,W
MOVWF Old0
MOVF Buffer1,W
MOVWF Old1
MOVF Buffer2,W
MOVWF Old2
MOVF Buffer3,W
MOVWF Old3
MOVF Buffer4,W
MOVWF Old4
MOVF Buffer5,W
MOVWF Old5
MOVF Buffer6,W
MOVWF Old6
MOVF Buffer7,W
MOVWF Old7
1998 Microchip Technology Inc. DS51137B-page 55
microID™ 125
k
Hz Design Guide
MOVF Buffer8,W
MOVWF Old8
MOVF Buffer9,W
MOVWF Old9
MOVF BufferA,W
MOVWF OldA
MOVF BufferB,W
MOVWF OldB
GOTO BigLoop1
Same
TxTag ;- Transmit tag
BSF _LED2 ; LEDs “Found tag”
CALL Delay07 ; |
BCF _LED1 ; |
MOVLW d’4’ ; Beep at 3597Hz for 1024 cycles
MOVWF BeepCtrHi ; |
MOVLW d’0’ ; |
MOVWF BeepCtrLo ; |
BeepLoopJ1 ; |
GOTO BeepLoopJ2 ; |
BeepLoopJ2 ; |
MOVLW Beep1 ; |
MOVWF BeepPort ; |
MOVLW d’34’ ; |
MOVWF DelayReg ; |
BeepD1 ; |
CLRWDT ; |
DECFSZ DelayReg,f ; |
GOTO BeepD1 ; |
MOVLW Beep2 ; |
MOVWF BeepPort ; |
MOVLW d’32’ ; |
MOVWF DelayReg ; |
NOP ; |
GOTO BeepD2 ; |
BeepD2 ; |
CLRWDT ; |
DECFSZ DelayReg,f ; |
GOTO BeepD2 ; |
DECFSZ BeepCtrLo,f ; |
GOTO BeepLoopJ1 ; |
DECFSZ BeepCtrHi,f ; |
GOTO BeepLoopJ2 ; |
NOP ; |
MOVLW Beep0 ; |
MOVWF BeepPort ; |
CALL RS232CR ; Transmit tag info
MOVLW ‘F’ ; |
CALL RS232TxW ; |
MOVLW ‘S’ ; |
CALL RS232TxW ; |
MOVLW ‘K’ ; |
CALL RS232TxW ; |
MOVLW ‘ ‘ ; |
CALL RS232TxW ; |
MOVLW ‘/’ ; |
CALL RS232TxW ; |
MOVLW ‘8’ ; |
CALL RS232TxW ; |
MOVLW ‘-’ ; |
CALL RS232TxW ; |
MOVLW ‘/’ ; |
CALL RS232TxW ; |
MOVLW ‘1’ ; |
microID™ 125
k
Hz Design Guide
DS51137B-page 56 1998 Microchip Technology Inc.
CALL RS232TxW ; |
MOVLW ‘0’ ; |
CALL RS232TxW ; |
CALL RS232CR ; |
MOVLW ‘T’ ; |
CALL RS232TxW ; |
MOVLW ‘b’ ; |
CALL RS232TxW ; |
MOVLW ‘i’ ; |
CALL RS232TxW ; |
MOVLW ‘t’ ; |
CALL RS232TxW ; |
MOVLW ‘=’ ; |
CALL RS232TxW ; |
MOVLW ‘5’ ; |
CALL RS232TxW ; |
MOVLW ‘0’ ; |
CALL RS232TxW ; |
MOVLW ‘T’ ; |
CALL RS232TxW ; |
MOVLW ‘c’ ; |
CALL RS232TxW ; |
MOVLW ‘y’ ; |
CALL RS232TxW ; |
CALL RS232CR ; |
MOVLW ‘C’ ; |
CALL RS232TxW ; |
MOVLW ‘o’ ; |
CALL RS232TxW ; |
MOVLW ‘n’ ; |
CALL RS232TxW ; |
MOVLW ‘s’ ; |
CALL RS232TxW ; |
MOVLW ‘t’ ; |
CALL RS232TxW ; |
MOVLW ‘a’ ; |
CALL RS232TxW ; |
MOVLW ‘n’ ; |
CALL RS232TxW ; |
MOVLW ‘t’ ; |
CALL RS232TxW ; |
CALL RS232CR ; |
MOVLW ‘T’ ; |
CALL RS232TxW ; |
MOVLW ‘t’ ; |
CALL RS232TxW ; |
MOVLW ‘a’ ; |
CALL RS232TxW ; |
MOVLW ‘g’ ; |
CALL RS232TxW ; |
MOVLW ‘=’ ; |
CALL RS232TxW ; |
MOVLW ‘9’ ; |
CALL RS232TxW ; |
MOVLW ‘6’ ; |
CALL RS232TxW ; |
MOVLW ‘T’ ; |
CALL RS232TxW ; |
MOVLW ‘b’ ; |
CALL RS232TxW ; |
MOVLW ‘i’ ; |
CALL RS232TxW ; |
MOVLW ‘t’ ; |
CALL RS232TxW ; |
CALL RS232CR ; |
MOVLW ‘P’ ; |
1998 Microchip Technology Inc. DS51137B-page 57
microID™ 125
k
Hz Design Guide
CALL RS232TxW ; |
MOVLW ‘o’ ; |
CALL RS232TxW ; |
MOVLW ‘l’ ; |
CALL RS232TxW ; |
MOVLW ‘a’ ; |
CALL RS232TxW ; |
MOVLW ‘r’ ; |
CALL RS232TxW ; |
MOVLW ‘i’ ; |
CALL RS232TxW ; |
MOVLW ‘t’ ; |
CALL RS232TxW ; |
MOVLW ‘y’ ; |
CALL RS232TxW ; |
MOVLW ‘ ‘ ; |
CALL RS232TxW ; |
MOVLW ‘0’ ; |
CALL RS232TxW ; |
CALL RS232CR ; |
MOVLW BufferB ; Transmit tag ID
MOVWF FSR ; |
TxLoop1 ; |
SWAPF INDF,W ; |
CALL RS232TxDigit ; |
MOVF INDF,W ; |
CALL RS232TxDigit ; |
DECF FSR,f ; |
BTFSC FSR,4 ; |
GOTO TxLoop1 ; |
CALL RS232CR ; |
GOTO BigLoop1 ; goto BigLoop1
end
microID™ 125
k
Hz Design Guide
DS51137B-page 58 1998 Microchip Technology Inc.
NOTES:
1998 Microchip Technology Inc. DS51138B-page 59
MmicroID™ 125 kHz DESIGN GUIDE
1.0 INTRODUCTION
This app licat ion not e is written as a re ference guide for
PSK reader designers. Microchip Technology Inc.
provides basic reader schematic for the MCRF200
customers as a part of this design guide. The circuit is
designed for a read range of 3 ~ 5 inches with an
access control card. The microID PSK Reader (demo
unit), which is bui lt based on the PSK ref erence design,
is available in the microID Designers Kit (DV103001).
The circuit can be modified for longer read range or
other applications with the MCRF200. An electronic
copy of the PSK microID PICmicro® source code is
available upon request.
2.0 READER CIRCUITS
The RFID read er consi sts of tr an smitting an d receiv ing
sections. It transmits a carrier signal, receives the
backscattering signal, and performs data processing.
The reader also communicates with an external host
computer. A basic block diagram of the typical RFID
reader is shown in Figure 2-1.
FIGURE 2-1: BLOCK DIAGRAM OF TYPICAL RFID READER FOR PSK SIGNAL (125 kHz)
(4 MHz Crystal Oscillator) 32
÷Carrier Signal Amplifier
(Power Driver)
Env elope Detector
Filter, Amplifier
Pulse Shaping,
Phase Comparator
and
Interface with
Host Computer
Transmitting Section
Antenna Coil
CLK
To Host Computer
Serial Interface (RS-232)
125 kHz
Time Base Signal Generator
Microcontroller
Data Decoding
Receiving Section
Circuits
PSK Reader Reference Design
PICmicro is a registered trademark of Microchip Technology Inc.
microID™ 125
k
Hz Design Guide
DS51138B-page 60 1998 Microchip Technology Inc.
2.1 Transmitting Section
The tr ansmitt ing se ction co ntains c ircui tr y for a ca rrie r
signal (125 kHz), power amplifiers, and a tuned
antenna coil.
The 125 kHz carrier signal is typically generated by
dividing a 4 MHz (4 MHz/32 = 125 kHz) crystal
osci lla tor si gna l. The signa l is am plif ie d befor e it is fed
into the antenna tunin g circuit. A com plementary pow er
amplifier circuit is typically used to boost the
transmitting signal level.
An antenna impedance tuning circuit consisting of
capacitors is used to maximize the signal level at the
carrier frequency. This tuning circuit is needed to form
an exact LC resonant circuit for the carrier signal. The
tuning compensates the variations in the component
values and the perturbation of coil inductance due to
env ironm ent effec t. A design guide for the an tenna coi l
is given in
AN678, RFID Coil Design,
page 25.
2.1.1 LIMITS ON TRANSMITTING SIGNAL LE V EL
(FCC PART 15) IN THE USA
Each country limits the signal strength of the RF wave
that is intentionally radiated by a device. In the USA, the
signal strength of the carrier signal (125 kHz) radiating
from the antenna coil must comply with the FCC (Fed-
eral Co mmuni cat ions Com miss ion) part 15 r egu lati on.
The signal level is specified by the 47 CFR Part
15.209a of the federal regulation. For a 125 kHz signal,
the FCC limits the signal level to 19.2 µV per meter, or
25.66 dBµV (i.e., 20 log(19.2) = 25.66 dBµV), at 300
meters away from the antenna. For a close distance
measurement, an extrapolation rule (40 dB per
decade) is applied (Part 15.31.f.2). For example, the
signal lev el at 30 meters aw ay from the device must not
exceed:
25.66 dBµV + 40 dBµV = 65.66 dBµV
2.2 Receiving Section
The receiving section consists of an antenna coil,
demodulator, filter, amplifier, pulse shaping, phase
comparator, and microcontroller. In applications for
pro ximity rea d-range, a single coil is often use d for both
transmitting and receiving. For long read range
application, however, separated antennas may be
used. More details on the antenna coil are given in
AN678, RFID Coil Design,
page 25.
In the PSK communication protocol, the phase of the
modulation signal changes with the data. Two most
common types of phase encoding method are: (a)
change phase at a ny dat a change (‘ 0’ to ‘1’ o r ‘1’ to ‘0’),
and (b) chan ge phase at ‘1’ . A typical data rate for PSK
applications is one half of the carrier frequency, and it
is faster than FSK. Howeve r, it requires a wider band-
width than FSK.
The PSK reader needs two steps for a full recover y of
the data. The first step is demodulating the backscat-
tering signal, and the second step is detecting the
phase changes in the demodulation signal.
The demodulation is accomplished by detecting the
envelope of the carrier signal. A full-wave
capacitor-filtered rectifier circuit is used for the
demodulation process. A diode detects the peak
voltage of the back scattering signal. The voltage is then
fed into an RC charging/discharging circuit. The RC
time constant must be small enough to allow the
voltage across C to fall fast e nough to k ee p in ste p with
the envelope. However, the time constant must not be
so small as to introduce excessive ripple. The
demodulated signal must then pass through a filter, an
amplifier, signal shaping, and phase comparator
circuits before it is fed to the microcontroller. The
microcontroller performs data decoding and
communicates with the host computer through an
RS-232 or other serial interface protocols.
1998 Microchip Technology Inc. DS51138B-page 61
microID™ 125
k
Hz Design Guide
3.0 microID PSK READER
The MCRF2 00 can be c onfigu red with eithe r PSK_1 or
PSK_2 modulation. The PSK_1 changes the phase of
the modulation signal on any change of the data
(i.e., 0 to 1 or 1 t o 0). T he PSK_2 ch anges the p hase of
the modulation signal on the first clock edge of a data
‘1’. Figure 3-1 shows the optional PSK encoding
protocols. The PSK encoded data is amplitude modu-
lating the carrier signal. A typical PSK modulated signal
is shown in Figure 3 in AN680,
Passive RFID Basics
page 15.
This reference reader was designed for use with an
MCRF20 0 with 08Dh i n its confi gurat ion registe r , whic h
represents PSK_1, NRZ Direct, Fc/32, data rate, and
128 bits.
The electronic circuitry for the PSK reader is shown in
Figure 3-1. The reader needs +9 to +15 VDC power
supply. The 125 kHz carrier signal is generated by
dividing the 4 MHz time-base signal that is generated
by a crystal oscillator. A 16-stage binary ripple counter
(74HC4060) is used for this purpose. The 74HC4060
also provides a clock signal for the PIC16C84 micro-
controller. Signal from the U8 is also used as a phase
reference for receiving signals.
The 125 kHz signal is passed to an RF choke (L1) and
filter befo re it is fed into a po wer ampli fier that is formed
by a pair of complemen t ary bipola r transistors (Q2 and
Q3).
For long read-range applications, this power amplifier
circuit can be modifi ed. Power M OSFETs may be used
instead of bipolar transistors (2N2222). These power
MOSFETs can be driven by +24 VDC power supply. A
push-pull predriver can be added at the front of the
complementary circuit. This modification will enhance
the signal level of the carrier signal.
The reader circuit uses a single coil for both transmit-
ting and receiving signals. An antenna coil
(L2: 1.62 mH) and a re sonant capacito r (C21: 1000 p F)
forms a series resonant circuit for 125 kHz resonance
frequency. Since the C21 is grounded, the carrier signal
(125 kHz) is fil t ere d out to the gro un d afte r pas si ng th e
antenna coil. The cir c uit provides minimum impedance
at the resonance frequency. This results in maximizing
the antenna current, and therefore, the magnetic field
strength is maximized.
In the circuit, D7 and D8 are amplitude demodulators
that are detecting the envelope of the backscattering
signal . D7 provi des a current p ath during a po sitiv e half
cycle and the D8 during the negative half cycle. The
detected envelope signal is charged into the C27. A
discharge path for the voltage charged in the C27 is
provided by R33. This voltage passes active filters
(U11:C) and the pulse shaping circuitry (U11:A).
The output from the U11 i s a sq uare wave at 62.5 kHz ,
which exhibits 180 degree phase-shifts in accordance
with changes in the data stream from the tag. This sig-
nal is used as a cloc k for D flip-flo p (U6:A) for wh ich the
D input is a reference 62.5 kHz square wave derived
from the 125 kHz transmitting signal. As the phase of
the received signal changes, the output of the flip-flop
changes, based on whether the clock in g oc cu rs d uring
the high or low portions of the reference signal. The
recovered data signal is fed to the input I/O pin of the
PICmicro MCU (U7) for decoding.
One of the major problems encountered with the PSK
reader is that the phase of the returned signal with
respect to a reference signal is, for several reasons,
indeterminate. If the transitions of the incoming signal
and the reference are occurring at the same time, the
outp ut of the D flip-f lop wil l be unpred ictable. To guar-
antee that this does not happen, additional circuits
have been added.
The rece ive d 62.5 kHz signal is buff ered b y U9:D and a
pulse is genera ted upon e v ery t ransition of the rece ived
signal by U4:C. Likewise, U4:B provides a string of
pulses on every transition of the reference 62.5 kHz
signal . Note that t hese pulse strings are a t 125 kHz an d
are independent of the phase state of the received
signal.
These pu lses are fed to the set a nd re set lin es o f U5:A
and resul t in a 125 k Hz ou tput at Q wh ose dut y cyc le is
proportional to the phase difference between the two
pulse signals. If the duty cycle is near 50%, then the
transitions of the 62.5 kHz signals are approximately 90
degr ees differe nt w hich is id eal f or PSK de modul ation.
FIGURE 3-1: PSK DATA MODULATION
P
P
PP
PP
PP
PP
PP
‘0’ ‘0’ ‘1’‘1’ EE Data
PSK 1
Change on Data
PSK 2
Change on ‘1’
microID™ 125
k
Hz Design Guide
DS51138B-page 62 1998 Microchip Technology Inc.
R6 and C10 filter the output of U5:A resulting in a DC
level proportional to the phase shift. This level is the
input to a wi ndo w detec tor con sisting of U10 a nd U4 :A.
If the DC level is near the midpoint, the output of
comparator U10:B would be high and the output of
comparator U10:A would be low. Therefore, the output
of U4:A w ould be high. If the DC le v el is highe r than the
reference level set by R21, R26, and R30 then the
output s of bo th compar ator s w ould be hi gh, res ultin g in
a low out put from U4: A. Sim ila rly, if the DC level is low,
both outputs would be low, which would also resu lt in a
low output at U4:A.
Note that the 125 kHz signal from which the 62.5 kHz
reference is obtained passes through gate U4:D. A
change of the state on the control output to this gate
allows the 125 kHz signal to be 180 degree
phase-shifted. This results in a phase-shift in the 62.5
kHz reference of 90 degrees. If the output of the U9:C
is low, the flip-flop U5:B will maintain its current state.
If the output of U4:A goes low, which would signify an
undesirable phase relationship between the 62.5 kHz
signals, then the output of U9:C would have a transition
to high, causing U5:B to change state. This would
change the reference phase 90 degrees, thus bringing
the phases of the 62.5 kHz signals back into a desirable
relationship and return the output of U4:A to a high
state.
In the event that no tag is present, Q of U5:A is always
high which makes the output of U10:B low. This turns
on an os cill ator co nsist ing of U 9:A, U9 :B , C8, R 15, an d
R19. This oscillator toggles U5:B at about 200 Hz,
allowing the reader to be looking for a tag signal with
both reference signal phases. When a good tag signal
appears, the circuit locks on in a good phase
relationship and demodulates the incoming 62.5 kHz
signal. As the tag comes closer to the reader , the phase
will be shift for a number of reasons. If the shift is
suffici ent, the reference signal will shi ft as necessary to
maintain good demodulation.
The PIC16C84 microcontroller performs data decoding
and communicates with host computer via an RS-232
serial interface.
1998 Microchip Technology Inc. DS51138B-page 63
microID™ 125
k
Hz Design Guide
4.0 PSK READER SCHEMATIC
PIC16C84
microID™ 125
k
Hz Design Guide
DS51138B-page 64 1998 Microchip Technology Inc.
5.0 PSK READER BILL OF MATERIALS
Item # Qty Part # Reference
Designator Part Description Manufacturer Vendor Vendor Part #
1 1 110-93-314-41-001 xU6 SOCKET, 14P COLLET
OPEN FR AM E
(0.300W)
MILL-MAX DIGIKEY ED3314-ND
2 1 DE9S-FRS P2 CONN, D-SUB 9P
RECPT RT ANGLE SPC
TECHNOLOGY
3 1 DJ005B P1 JACK, POWER, 2.5mm
DC PC MOUNT LZR
ELECTRONICS
4 1 PKM22EPP-4001 SP1 BUZZER, PIEZO,
4KHz, 3-20V MURATA
5 2 D100D20U2MHAAAC C7, C15 CAP, 10 pF CER DISK
RAD, 100V PHILIPS DIGIKEY 1301PH-ND
6 2 D 220J20COGHA AAC C2, C3 CAP, 22 pF CER DISK
RAD COG 100V PHILIPS DIGIKEY 1330PH-ND
7 7 ECU-S1H221JCA C13, C14,
C23-C25,
C29, C31
CAP, 220pF, CER
MONO, RAD, 50V, 5% PANASONIC DIGIKEY P4929-ND
8 1 ECQ-P6102JU C21 CAP, 0.001 µF
POLYPROPYLENE
630V
PHILIPS DIGIKEY P3497-ND
9 2 2222 370 52102 C26, C27 CAP, 0.001 µF METAL
FILM, 5%, RAD, 400V PHILIPS DIGIKEY 3001PH-ND
10 1 ECU-S 2A152J CB C22 CAP, 1500 pF MONO-
LITH CERM, 5%, RAD,
100V
PHILIPS DIGIKEY P4863-ND
11 3 ECU-S2A182JCB C9, C18, C20 CAP, 1800 pF MONO-
LITH CERM, 5%, RAD,
100V
PHILIPS DIGIKEY P4864-ND
12 1 ECU-S 1H682JCB C12 CAP, 6800 pF 50V
CERAMIC MONO 5% PANASONIC DIGIKEY P4946-ND
13 2 ECK- F1H 103ZF C8, C10 CAP, 0.01 µF CERM
DISK, +80/-20%, RAD,
50V
PHILIPS DIGIKEY P4066A-ND
14 1 ECQ-V 1103JM C16 CAP, 0.01 µF 100V
STACK METAL FILM PANASONIC DIGIKEY P4713-ND
15 3 ECQ-E1104KF C4, C11, C30 CAP, 0.1 µUF 100VDC
10% RAD METAL
POLY CAP
PANASONIC DIGIKEY EF1104-ND
16 1 ECU-S1H121JCA C28 CAP, 120 pF, CER
MONO, RAD, 50V, 5% PANASONIC DIGIKEY P4926-ND
17 3 ECE-A16Z10 C5, C6, C19 CAP, 10 µF, ELECTRO,
RAD, 16V, 20% PANASONIC DIGIKEY P6616-ND
18 1 ECE-A25Z100 C1 CAP, 100 µF, ELEC-
TRO, RAD, 25V, 20% PANASONIC DIGIKEY P6616-ND
19 6 1 N4148 D1-D6 DIODE, GENERAL
PURPOSE, 1N4148
(DO-35)
DIODES INC. DIGIKEY 1N4148DITR-
ND
20 2 1 N4936 D7, D8 DIODE, 1A 400V FAST-
RECOVERY RECTI-
FIER
DIODES INC DIGIKEY 1N4936CT-ND
21 1 - SPARE - LED1, C17 -SPARE- LOCATION
DO NOT INSTALL
22 2 78F102J L1, L3 I NDUCTOR, 1000 µH,
COATED JW MILLER DIGIKEY M7849-ND
23 1 MCT0003-001 L2 INDUCTOR, 1.62 mH CORNELL
DUBILIER
1998 Microchip Technology Inc. DS51138B-page 65
microID™ 125
k
Hz Design Guide
24 3 2N2907A Q1, Q3, Q4 TRANSISTOR, PNP,
2N2907A, TO-92 MOTOROLA
25 1 2N2222A Q2 TRANSISTOR, NPN,
2N2222A, TO-92 MOTOROLA ALLIED 2N2222A
26 2 5043CX10R0J R10, R13 RES , CF 10 OHM 1/4W
5% PHILLIPS
27 1 82E CR-1/4W -B 5% R11 RES, CF 82 OHM 1/4W
5% YAGEO DIGIKEY 82QBK-ND
28 1 5043CX100R0J R18 RES, CF 100 OHM
1/4W 5% PHILLIPS
29 1 5043CX220R0J R40 RES, CF 220 OHM 5%
1/4W PHILLIPS
30 3 5043CX330R0J R4, R14, R17 RES, CF 330 OHM
1/4W 5% PHILLIPS
31 1 5043CX470R0J R7 RES, CF 470 OHM 5%
1/4W PHILLIPS
32 1 1K21 MF-1/4W-B 1% R27 RES, MF 1.21K OHM 1/
4W 1% YAGEO DIGIKEY 1.21KXBK-ND
33 1 1K8 CR-1/4W-B 5% R3 RES, CF 1.8K OHM
1/4W 5% YAGEO DIGIKEY 1.8KQBK-ND
34 1 1K82 MF-1/4W-B 1% R24 RES, MF 1.82K OHM 1/
4W 1% YAGEO DIGIKEY 1.82KXBK-ND
35 1 3K3 CR-1/4W-B 5% R2 RES, CF 3.3K OHM
1/4W 5% YAGEO DIGIKEY 3.3KQBK-ND
36 1 5043CX4K700J R29 RES, CF 4.7K 5%
1/4W, AXIAL PHILLIPS
37 6 10K CR-1/4W-B 5% R1, R12, R 25,
R35, R39,
R41
RES, CF 10K OHM
1/4W 5% YAGEO DIGIKEY 10KQBK-ND
38 3 5043ED10K00F R31, R43,
R44 RES, MF 10K 1/4W 1% PHILLIPS
39 2 12K CR-1/4W-B 5% R20, R38 RES, CF 12K OHM
1/4W 5% YAGEO DIGIKEY 12KQBK-ND
40 1 16K5 MF-1/4W-B 1% R34 RES, MF 16.5K OHM
1/4W 1% YAGEO DIGIKEY 16.5KXBK-ND
41 2 22K CR-1/4W-B 5% R6, R8 RES, CF 22K OHM
1/4W 5% YAGEO DIGIKEY 22KQBK-ND
42 1 47K5 MF-1/4W-B 1% R37 RES, MF 47.5K OHM
1/4W 1% YAGEO DIGIKEY 47.5KXBK-ND
43 1 56K CR-1/4W-B 5% R32 RES, CF 56K OHM
1/4W 5% YAGEO DIGIKEY 56KQBK-ND
44 5 5043CX100K0J R9, R16, R21,
R22, R30 RES, CF 100K 5%
1/4W PHILLIPS
45 1 180K CR-1/4W-B 5% R26 RES, CF 180K OHM
1/4W 5% YAGEO DIGIKEY 180KQBK-ND
46 1 270K CR-1/4W-B 5% R15 RES, CF 270K OHM
1/4W 5% YAGEO DIGIKEY 270KQBK-ND
47 7 1M0 CR-1/4W-B 5% R5, R19, R23,
R28, R33,
R36, R42
RES, CF 1.0M OHM
1/4W 5% YAGEO DIGIKEY 1.0MQBK-ND
48 1 LM78M12CT U1 IC, REG 12V 3 TERM
POS (TO-220) NATIONAL DIGIKEY LM78M12CT-
ND
49 1 LM78L05ACZ U2 IC, REG, +5V 0.1
A TO-92 NATIONAL DIGIKEY LM78L05ACZ-
ND
Item # Qty Part # Reference
Designator Part Description Manufacturer Vendor Vendor Part #
microID™ 125
k
Hz Design Guide
DS51138B-page 66 1998 Microchip Technology Inc.
50 1 MM74HC04N U3 IC, HEX INVERTER
14P DIP FAIRCHILD
SEMICONDUC-
TOR
DIGIKEY MM74HC04N-
ND
51 1 CD4030CN U4 IC , QUAD EXCLUSIVE
OR GATE, 14P DIP FAIRCHILD
SEMICONDUC-
TOR
DIGIKEY CD4030CN-
ND
52 2 CD4013BCN U5, U6 IC , DUAL D FLIP FLOP,
14P DIP FAIRCHILD
SEMICONDUC-
TOR
DIGIKEY CD4013BCN-
ND
53 1 PIC16C84/P U7 IC, PIC16C84 PLAS-
TIC, 14P DIP MICROCHIP
54 1 MM74HC4060N U8 IC, 14 STA GE BINARY
COUNTER, 16P DIP FAIRCHILD
SEMICONDUC-
TOR
DIGIKEY MM74HC4060
N-ND
55 1 CD4001BCN U9 IC, QUAD 2-IN NOR
GATE, 14P DIP FAIRCHILD
SEMICONDUC-
TOR
DIGIKEY CD4001BCN-
ND
56 1 TLC3702CP U10 IC, DU AL VOLTAGE
COMPARATORS,
1000mW, 8P DIP
TEXAS
INSTRUMENTS MOUSER TLC3702CP
57 1 TL084C N U11 IC, QUAD OP AMP, 1
4P DIP SGS TH OMP-
SON MOUSER 511-TL084CN
58 1 EFO-EC4004A 4 Y1 RES ONATOR,
4.00MHZ CERAMIC
W/CAP
PANASONIC DIGIKEY PX400-ND
Item # Qty Part # Reference
Designator Part Description Manufacturer Vendor Vendor Part #
1998 Microchip Technology Inc. DS51138B-page 67
microID™ 125
k
Hz Design Guide
6.0 PSK SOURCE CODE FOR THE PICmicro® MCU
The following source code is for the PIC16C84 microcontroller used in the PSK reader electronics.
; #=#=#=#=#=#=#=#=#=#=#= PROJECT Microchip PSK Reader =#=#=#=#=#=#=#=#=#=#=#
;
; PIC16C84 running at 4MHz, Ti=1us
; ///////////////////////////////////////////////////////////////////////////
; Revision history
; ///////////////////////////////////////////////////////////////////////////
;
; Ver Date Comment
;
; 0.01 29 Dec 97 Copied from MChip\Reader\PSK
; 0.03 28 Jan 98 TRANSMIT TAB (h’09’) REGULARLY
; 20 Aug 98 Modified to correct PSK comments
;
; Tbit=32Tcy=256Ti
; Ttag=128Tbit
; Header=h’802A’
;
;
processor pic16c84
#include “p16c84.inc”
__config b’11111111101001’
; Code Protect on, power-up timer on, WDT off, XT oscillator
#define _CARRY STATUS,0
#define _ZERO STATUS,2
#define _TO STATUS,4
#define _RP0 STATUS,5
#define _BUZZ1 PORTA,0
#define _BUZZ2 PORTA,1
#define _RS232TX PORTA,2
#define _RS232RX PORTA,3
#define _T0CKI PORTA,4
StartPORTA = b’01100’
StartTRISA = b’11000’
BeepPort = PORTA
Beep0 = StartPORTA
Beep1 = StartPORTA | b’00001’
Beep2 = StartPORTA | b’00010’
#define _DATA_IN PORTB,0
#define _UNUSED1 PORTB,1
#define _LED1 PORTB,2
#define _LED2 PORTB,3
#define _UNUSED2 PORTB,4
#define _UNUSED3 PORTB,5
#define _UNUSED4 PORTB,6
#define _UNUSED5 PORTB,7
StartPORTB = b’00000000’
StartTRISB = b’00000001’
StartOPTION = b’00001111’ ; TMR0 internal, prescaler off
BO3 = h’0C’
DelayReg = h’0C’
BitCtr = h’0D’
BeepCtrHi = h’0D’
TxByte = h’0E’
BeepCtrLo = h’0E’
Buffer0 = h’10’ ; --- IMMOBILE --- IMMOBILE --- IMMOBILE --- IMMOBILE
microID™ 125
k
Hz Design Guide
DS51138B-page 68 1998 Microchip Technology Inc.
Buffer1 = h’11’ ; |
Buffer2 = h’12’ ; |
Buffer3 = h’13’ ; |
Buffer4 = h’14’ ; |
Buffer5 = h’15’ ; |
Buffer6 = h’16’ ; |
Buffer7 = h’17’ ; |
Buffer8 = h’18’ ; |
Buffer9 = h’19’ ; |
BufferA = h’1A’ ; |
BufferB = h’1B’ ; |
BufferC = h’1C’ ; |
BufferD = h’1D’ ; |
BufferE = h’1E’ ; |
BufferF = h’1F’ ; |
Old0 = h’20’ ; |
Old1 = h’21’ ; |
Old2 = h’22’ ; |
Old3 = h’23’ ; |
Old4 = h’24’ ; |
Old5 = h’25’ ; |
Old6 = h’26’ ; |
Old7 = h’27’ ; |
Old8 = h’28’ ; |
Old9 = h’29’ ; |
OldA = h’2A’ ; |
OldB = h’2B’ ; |
OldC = h’2C’ ; |
OldD = h’2D’ ; |
OldE = h’2E’ ; |
OldF = h’2F’ ; |
SKIP macro
BTFSC PCLATH,7
endm
org h’0000’ ; *#*#*#* RESET VECTOR *#*#*#*
CLRF PCLATH
CLRF INTCON
CLRF STATUS
GOTO RESET_A
org h’0004’ ; *#*#*#* INTERRUPT VECTOR *#*#*#*
CLRF PCLATH
CLRF INTCON
CLRF STATUS
GOTO RESET_A
; ***** Subroutines, Page 0
Delay07 ;[0] Delay 7Ti
NOP ; |
Delay06 ;[0] Delay 6Ti
NOP ; |
Delay05 ;[0] Delay 5Ti
NOP ; |
Delay04 ;[0] Delay 4Ti
RETLW 0 ; |
RS232CR ;[1] Transmit CR on RS232
MOVLW d’13’ ; |
GOTO RS232TxW ; |
RS232TxDigit ;[1] Transmit LSnybble of W on RS232
ANDLW h’0F’ ; |
MOVWF TxByte ; |
MOVLW h’0A’ ; |
1998 Microchip Technology Inc. DS51138B-page 69
microID™ 125
k
Hz Design Guide
SUBWF TxByte,W ; |
BTFSS _CARRY ; |
GOTO DigitLT10 ; |
DigitGE10 ; |
MOVLW ‘A’-’0’-h’0A’ ; |
ADDWF TxByte,f ; |
DigitLT10 ; |
MOVLW ‘0’ ; |
ADDWF TxByte,W ; |
RS232TxW ;[1] Transmit W on RS232 at 9615 baud
MOVWF TxByte ; | TxByte=W
RS232Tx ;[1] Transmit TxByte - 104us = 9615.4 baud
BSF _RS232TX ; | Stop bit
MOVLW d’35’ ; | |
MOVLW DelayReg ; | |
RS232TxD1 ; | |
DECFSZ DelayReg,f ; | |
GOTO RS232TxD1 ; | |
BCF _RS232TX ; | Start bit
NOP ; | |
MOVLW d’32’ ; | |
MOVWF DelayReg ; | |
RS232TxD2 ; | |
DECFSZ DelayReg,f ; | |
GOTO RS232TxD2 ; | |
CLRF BitCtr ; | BitCtr=#8
BSF BitCtr,3 ; | |
RS232TxL1 ; | {% -4Ti
BTFSC TxByte,0 ; | Transmit TxByte.0, RR TxByte
GOTO RS232TxBit1 ; | |
NOP ; | |
RS232TxBit0 ; | |
BCF _RS232TX ; | |
BCF _CARRY ; | |
GOTO RS232TxBitDone ; | |
RS232TxBit1 ; | |
BSF _RS232TX ; | |
BSF _CARRY ; | |
GOTO RS232TxBitDone ; | |
RS232TxBitDone ; | |
RRF TxByte,f ; | |% 4Ti
MOVLW d’30’ ; | delay 1 bit
MOVWF DelayReg ; | |
GOTO RS232TxD3 ; | |
RS232TxD3 ; | |
DECFSZ DelayReg,f ; | |
GOTO RS232TxD3 ; | |
DECFSZ BitCtr,f ; | DEC BitCtr
GOTO RS232TxL1 ; | } until (BitCtr==#0)
CALL Delay04 ; | delay
BSF _RS232TX ; | stop bit
RETLW 0 ; end
; ***** End of subroutines, Page 0
RESET_A
CLRWDT
; Initialise registers
CLRF STATUS ; | Access register page 0
CLRF FSR ; | FSR=#0
MOVLW StartPORTA ; | Initialise PORT and TRIS registers
MOVWF PORTA ; | |
MOVLW StartPORTB ; | |
MOVWF PORTB ; | |
BSF _RP0 ;^| |
MOVLW StartTRISA ;^| |
microID™ 125
k
Hz Design Guide
DS51138B-page 70 1998 Microchip Technology Inc.
MOVWF TRISA ;^| |
MOVLW StartTRISB ;^| |
MOVWF TRISB ;^| |
MOVLW StartOPTION ;^| Initialise OPTION register
MOVWF OPTION_REG ;^| |
BCF _RP0 ; | |
CLRF Old0 ; | Clear Old buffer
CLRF Old1 ; | |
CLRF Old2 ; | |
CLRF Old3 ; | |
CLRF Old4 ; | |
CLRF Old5 ; | |
CLRF Old6 ; | |
CLRF Old7 ; | |
CLRF Old8 ; | |
CLRF Old9 ; | |
CLRF OldA ; | |
CLRF OldB ; | |
CLRF OldC ; | |
CLRF OldD ; | |
CLRF OldE ; | |
CLRF OldF ; | |
BigLoop1
BSF _LED1 ; LEDs “reading”
CALL Delay07 ; |
BCF _LED2 ; |
MOVLW h’09’ ; Transmit TAB regularly
CALL RS232TxW ; |
MOVLW d’128’ ; set BitCtr
MOVWF BitCtr ; |
GetEdge ; Get an edge on _DATA_IN
BTFSC _DATA_IN ; |
GOTO PreSync_H ; |
NOP ; |
PreSync_L ; |
BTFSC _DATA_IN ; |
GOTO PreSync_H ; |
BTFSC _DATA_IN ; |
GOTO PreSync_H ; |
DoSync_L ; |
CLRWDT ; |
BTFSS _DATA_IN ; |
GOTO DoSync_L ; |
BTFSS _DATA_IN ; |
GOTO DoSync_L ; |
GOTO Sync_Done ; |
; |
PreSync_H ; |
BTFSS _DATA_IN ; |
GOTO PreSync_L ; |
BTFSS _DATA_IN ; |
GOTO PreSync_L ; |
DoSync_H ; |
CLRWDT ; |
BTFSC _DATA_IN ; |
GOTO DoSync_H ; |
BTFSC _DATA_IN ; |
GOTO DoSync_H ; |
GOTO Sync_Done ; |
Sync_Done ; |% 6 to (+4) from edge, say 8 from edge
;% -120Ti from sample
NOP
MOVLW d’38’
MOVWF DelayReg
;% -117Ti from sample
1998 Microchip Technology Inc. DS51138B-page 71
microID™ 125
k
Hz Design Guide
ReadBit ; {% -3-DelayReg*3 Ti from sample
NOP ; delay
ReadBitD1 ; |
DECFSZ DelayReg,f ; |
GOTO ReadBitD1 ; |
CLRF BO3 ; BO3.1=_DATA_IN
BTFSC _DATA_IN ; |
INCF BO3,f ; |% effective sample time
BTFSC _DATA_IN ; |
INCF BO3,f ; |
BTFSC _DATA_IN ; |
INCF BO3,f ; |
BCF _CARRY ; _CARRY=BO3.1
BTFSC BO3,1 ; |
BSF _CARRY ; |
RLF Buffer0,f ; roll in _CARRY
RLF Buffer1,f ; |
RLF Buffer2,f ; |
RLF Buffer3,f ; |
RLF Buffer4,f ; |
RLF Buffer5,f ; |
RLF Buffer6,f ; |
RLF Buffer7,f ; |
RLF Buffer8,f ; |
RLF Buffer9,f ; |
RLF BufferA,f ; |
RLF BufferB,f ; |
RLF BufferC,f ; |
RLF BufferD,f ; |
RLF BufferE,f ; |
RLF BufferF,f ; |
; % 23Ti from sample = -233Ti from sample
MOVLW d’75’ ; set bit delay
MOVWF DelayReg ; |% -231Ti from sample
;% -6-DelayReg*3 Ti from sample
DECFSZ BitCtr,f ; DEC BitCtr
GOTO ReadBit ; } until (BitCtr==#0)
HeadSearch
MOVLW d’128’ ; set BitCtr
MOVWF BitCtr ; |
HeadSearchL1 ; {
MOVLW h’80’ ; if (header found)
XORWF BufferF,W ; |
BTFSS _ZERO ; |
GOTO NotHead0 ; |
MOVLW h’2A’ ; |
XORWF BufferE,W ; |
BTFSS _ZERO ; |
GOTO NotHead0 ; {
GOTO HeadPolarity0 ; goto HeadPolarity0
NotHead0 ; }
MOVLW h’7F’ ; if (inverse header found)
XORWF BufferF,W ; |
BTFSS _ZERO ; |
GOTO NotHead1 ; |
MOVLW h’D5’ ; |
XORWF BufferE,W ; |
BTFSS _ZERO ; |
GOTO NotHead1 ; {
GOTO HeadPolarity1 ; goto HeadPolarity1
NotHead1 ; }
RLF Buffer0,f ; ROL Buffer
RLF Buffer1,f ; |
RLF Buffer2,f ; |
RLF Buffer3,f ; |
microID™ 125
k
Hz Design Guide
DS51138B-page 72 1998 Microchip Technology Inc.
RLF Buffer4,f ; |
RLF Buffer5,f ; |
RLF Buffer6,f ; |
RLF Buffer7,f ; |
RLF Buffer8,f ; |
RLF Buffer9,f ; |
RLF BufferA,f ; |
RLF BufferB,f ; |
RLF BufferC,f ; |
RLF BufferD,f ; |
RLF BufferE,f ; |
RLF BufferF,f ; |
BCF Buffer0,0 ; |
BTFSC _CARRY ; |
BSF Buffer0,0 ; |
DECFSZ BitCtr,f ; DEC BitCtr
GOTO HeadSearchL1 ; } until (BitCtr==#0)
GOTO BigLoop1 ; goto BigLoop1
HeadPolarity1
COMF Buffer0,f
COMF Buffer1,f
COMF Buffer2,f
COMF Buffer3,f
COMF Buffer4,f
COMF Buffer5,f
COMF Buffer6,f
COMF Buffer7,f
COMF Buffer8,f
COMF Buffer9,f
COMF BufferA,f
COMF BufferB,f
COMF BufferC,f
COMF BufferD,f
COMF BufferE,f
COMF BufferF,f
HeadPolarity0
HeadFound
CheckSame
MOVF Buffer0,W
XORWF Old0,W
BTFSS _ZERO
GOTO NotSame
MOVF Buffer1,W
XORWF Old1,W
BTFSS _ZERO
GOTO NotSame
MOVF Buffer2,W
XORWF Old2,W
BTFSS _ZERO
GOTO NotSame
MOVF Buffer3,W
XORWF Old3,W
BTFSS _ZERO
GOTO NotSame
MOVF Buffer4,W
XORWF Old4,W
BTFSS _ZERO
GOTO NotSame
MOVF Buffer5,W
XORWF Old5,W
BTFSS _ZERO
GOTO NotSame
MOVF Buffer6,W
XORWF Old6,W
1998 Microchip Technology Inc. DS51138B-page 73
microID™ 125
k
Hz Design Guide
BTFSS _ZERO
GOTO NotSame
MOVF Buffer7,W
XORWF Old7,W
BTFSS _ZERO
GOTO NotSame
MOVF Buffer8,W
XORWF Old8,W
BTFSS _ZERO
GOTO NotSame
MOVF Buffer9,W
XORWF Old9,W
BTFSS _ZERO
GOTO NotSame
MOVF BufferA,W
XORWF OldA,W
BTFSS _ZERO
GOTO NotSame
MOVF BufferB,W
XORWF OldB,W
BTFSS _ZERO
GOTO NotSame
MOVF BufferC,W
XORWF OldC,W
BTFSS _ZERO
GOTO NotSame
MOVF BufferD,W
XORWF OldD,W
BTFSS _ZERO
GOTO NotSame
MOVF BufferE,W
XORWF OldE,W
BTFSS _ZERO
GOTO NotSame
MOVF BufferF,W
XORWF OldF,W
BTFSS _ZERO
GOTO NotSame
GOTO Same
NotSame
MOVF Buffer0,W
MOVWF Old0
MOVF Buffer1,W
MOVWF Old1
MOVF Buffer2,W
MOVWF Old2
MOVF Buffer3,W
MOVWF Old3
MOVF Buffer4,W
MOVWF Old4
MOVF Buffer5,W
MOVWF Old5
MOVF Buffer6,W
MOVWF Old6
MOVF Buffer7,W
MOVWF Old7
MOVF Buffer8,W
MOVWF Old8
MOVF Buffer9,W
MOVWF Old9
MOVF BufferA,W
MOVWF OldA
MOVF BufferB,W
MOVWF OldB
MOVF BufferC,W
MOVWF OldC
microID™ 125
k
Hz Design Guide
DS51138B-page 74 1998 Microchip Technology Inc.
MOVF BufferD,W
MOVWF OldD
MOVF BufferE,W
MOVWF OldE
MOVF BufferF,W
MOVWF OldF
GOTO BigLoop1
Same
TxTag ;- Transmit tag
BSF _LED2 ; LEDs “Found tag”
CALL Delay07 ; |
BCF _LED1 ; |
MOVLW d’4’ ; Beep at 3597Hz for 1024 cycles
MOVWF BeepCtrHi ; |
MOVLW d’0’ ; |
MOVWF BeepCtrLo ; |
BeepLoopJ1 ; |
GOTO BeepLoopJ2 ; |
BeepLoopJ2 ; |
MOVLW Beep1 ; |
MOVWF BeepPort ; |
MOVLW d’34’ ; |
MOVWF DelayReg ; |
BeepD1 ; |
CLRWDT ; |
DECFSZ DelayReg,f ; |
GOTO BeepD1 ; |
MOVLW Beep2 ; |
MOVWF BeepPort ; |
MOVLW d’32’ ; |
MOVWF DelayReg ; |
NOP ; |
GOTO BeepD2 ; |
BeepD2 ; |
CLRWDT ; |
DECFSZ DelayReg,f ; |
GOTO BeepD2 ; |
DECFSZ BeepCtrLo,f ; |
GOTO BeepLoopJ1 ; |
DECFSZ BeepCtrHi,f ; |
GOTO BeepLoopJ2 ; |
NOP ; |
MOVLW Beep0 ; |
MOVWF BeepPort ; |
CALL RS232CR ; Transmit tag info
MOVLW ‘P’ ; |
CALL RS232TxW ; |
MOVLW ‘S’ ; |
CALL RS232TxW ; |
MOVLW ‘K’ ; |
CALL RS232TxW ; |
MOVLW ‘/’ ; |
CALL RS232TxW ; |
MOVLW ‘2’ ; |
CALL RS232TxW ; |
CALL RS232CR ; |
MOVLW ‘T’ ; |
CALL RS232TxW ; |
MOVLW ‘b’ ; |
CALL RS232TxW ; |
MOVLW ‘i’ ; |
CALL RS232TxW ; |
MOVLW ‘t’ ; |
CALL RS232TxW ; |
1998 Microchip Technology Inc. DS51138B-page 75
microID™ 125
k
Hz Design Guide
MOVLW ‘=’ ; |
CALL RS232TxW ; |
MOVLW ‘3’ ; |
CALL RS232TxW ; |
MOVLW ‘2’ ; |
CALL RS232TxW ; |
MOVLW ‘T’ ; |
CALL RS232TxW ; |
MOVLW ‘c’ ; |
CALL RS232TxW ; |
MOVLW ‘y’ ; |
CALL RS232TxW ; |
CALL RS232CR ; |
MOVLW ‘C’ ; |
CALL RS232TxW ; |
MOVLW ‘o’ ; |
CALL RS232TxW ; |
MOVLW ‘n’ ; |
CALL RS232TxW ; |
MOVLW ‘s’ ; |
CALL RS232TxW ; |
MOVLW ‘t’ ; |
CALL RS232TxW ; |
MOVLW ‘a’ ; |
CALL RS232TxW ; |
MOVLW ‘n’ ; |
CALL RS232TxW ; |
MOVLW ‘t’ ; |
CALL RS232TxW ; |
CALL RS232CR ; |
MOVLW ‘T’ ; |
CALL RS232TxW ; |
MOVLW ‘t’ ; |
CALL RS232TxW ; |
MOVLW ‘a’ ; |
CALL RS232TxW ; |
MOVLW ‘g’ ; |
CALL RS232TxW ; |
MOVLW ‘=’ ; |
CALL RS232TxW ; |
MOVLW ‘1’ ; |
CALL RS232TxW ; |
MOVLW ‘2’ ; |
CALL RS232TxW ; |
MOVLW ‘8’ ; |
CALL RS232TxW ; |
MOVLW ‘T’ ; |
CALL RS232TxW ; |
MOVLW ‘b’ ; |
CALL RS232TxW ; |
MOVLW ‘i’ ; |
CALL RS232TxW ; |
MOVLW ‘t’ ; |
CALL RS232TxW ; |
CALL RS232CR ; |
MOVLW ‘P’ ; |
CALL RS232TxW ; |
MOVLW ‘o’ ; |
CALL RS232TxW ; |
MOVLW ‘l’ ; |
CALL RS232TxW ; |
MOVLW ‘a’ ; |
CALL RS232TxW ; |
MOVLW ‘r’ ; |
CALL RS232TxW ; |
MOVLW ‘i’ ; |
microID™ 125
k
Hz Design Guide
DS51138B-page 76 1998 Microchip Technology Inc.
CALL RS232TxW ; |
MOVLW ‘t’ ; |
CALL RS232TxW ; |
MOVLW ‘y’ ; |
CALL RS232TxW ; |
MOVLW ‘ ‘ ; |
CALL RS232TxW ; |
MOVLW ‘0’ ; |
CALL RS232TxW ; |
CALL RS232CR ; |
MOVLW BufferF ; Transmit tag ID
MOVWF FSR ; |
TxLoop1 ; |
SWAPF INDF,W ; |
CALL RS232TxDigit ; |
MOVF INDF,W ; |
CALL RS232TxDigit ; |
DECF FSR,f ; |
BTFSC FSR,4 ; |
GOTO TxLoop1 ; |
CALL RS232CR ; |
GOTO BigLoop1 ; goto BigLoop1
end
1998 Microchip Technology Inc. DS51166C-page 77
MmicroID™ 125 kHz DESIGN GUIDE
1.0 INTRODUCTION
This app licat ion not e is written as a re ference guide for
ASK reader designers. Microchip Technology Inc.
provides basic reader electronics circuitry for the
MCRF200 customers as a part of this design guide.
The circ uit i s de si gne d fo r a read ra nge of 3 ~ 5 inc he s
with an access control card. The microID ASK Reader
(demo uni t), whi ch is b ui lt ba sed on th e ASK refer enc e
design, is available in the microID Designers Kit
(DV103001). The circuit can be modified for longer
read r ange or other appl ications with the MCRF200 . An
electronic copy of the ASK microID PICmicro® source
code is available upon request.
2.0 READER CIRCUITS
The RFID read er consi sts of tr an smitting an d receiv ing
sections. It transmits a carrier signal, receives the
backscattering signal, and performs data processing.
The reader also communicates with an external host
computer. A basic block diagram of the typical ASK
RFID reader is shown in Figure 2-1.
FIGURE 2-1: BLOCK DIAGRAM OF TYPICAL RFID READER FOR ASK SIGNAL (125 kHz)
(4 MHz Crystal Oscillator) Carrier Signal Amplifier
(Power Driver)
Env elope Detector
Filter, Amplifier,
and Pulse Shaping
Interface with
Host Computer
Transmitting Section
Antenna Coil
CLK
To Host Computer
Serial Interface (RS-232)
125 kHz
Time Base Signal Generator
Microcontroller
Data Decoding
Receiving Section
÷ 32
ASK Reader Reference Design
PICmicro is a registered trademark of Microchip Technology Inc.
microID™ 125
k
Hz Design Guide
DS51166C-page 78 1998 Microchip Technology Inc.
2.1 Transmitting Section
The tr ansmitt ing se ction co ntains c ircui tr y for a ca rrie r
signal (125 kHz), power amplifiers, and a tuned
antenna coil.
The 125 kHz carrier signal is typically generated by
dividing a 4 MHz (4 MHz/32 = 125 kHz) crystal
osci lla tor si gna l. The signa l is am plif ie d befor e it is fed
into the antenna tunin g circuit. A com plementary pow er
amplifier circuit is typically used to boost the
rans mitting signal level.
An antenna impedance tuning circuit consisting of
capacitors is used to maximize the signal level at the
carrier frequency. The tuning compensates the
variations in the component values and the
perturbation of coil inductance due to environment
effect. A design guide for the antenna coil is given in
AN678, RFID Coil Design
.
2.1.1 LIMITS ON TRANSMITTING SIGNAL LE V EL
(FCC PART 15) IN THE USA
Each country limits the signal strength of the RF wave
that is intentionally radiated by a device. In the USA,
the signal strength of the carrier signal (125 kHz)
radiating from the antenna coil must comply with the
FCC (Federal Communications Commission) part 15
regulation. The signal level is specified by the 47 CFR
Part 15.209a of the federal regulation. For a 125 kHz
signal, the FCC limits the signal level to 19.2 µv per
meter, or 25.66 dBµV (i .e ., 20 l og(19.2) = 25.66 dBµV),
at 300 meters away from the antenna. For a close
distance measurement, an extrapolation rule (40 dB
per decade) is applied (Part 15.31.f.2). For example,
the signal le v el at 30 meters aw a y from the de vice must
not exceed:
25.66 dBµV + 40 dBµV = 65.66 dBµV
2.2 Receiving Section
The receiving section consists of an antenna coil,
demodulator, filters, amplifiers, and microcontroller. In
applic ations for clo se pro ximity read range, a single coi l
is often used for both transmitting and receiving. For
long read-range applications, however, separated
antennas may be used. More details on the antenna
coil are given in
AN678, RFID Coil Design
page 25.
In the ASK communication protocol, a ‘0’ and a ‘1’ are
represen ted b y an ampl itude s tatus of rec eivin g signa l.
Various data coding waveforms that are available by
MCRF200 are shown in Figure 1 in
AN680
Passive
RFID Basics
, page 1.
The demodulation of the ASK signal is accomplished
by detecting the envelope of the carrier signal. A half-
wave capacitor-filtered rectifier circuit is used for the
demodulation process. The peak voltage of the
back-scattering signal is detected by a diode, and this
voltage is then fed into an RC charging/discharging
circuit. The RC time constant must be small enough to
allo w the v olta ge ac ross C to fall fa st eno ugh to k eep in
step with the envelope. However, the time constant
must not be so small as to introduce ex cessive ripple.
The charging capacitor and load R has the following
relationship for a full recovery of the data signal.
where ωs and ωo are the angular frequencies of the
modula tion (data ) and ca rrier (125 kHz) , respect ive ly. R
is the load (discharging) resistor.
The dem odulated signal must then pa ss throug h a filt er
and signal shaping circuit before it is fed to the
microcontroller. The microcontroller performs data
decoding and communicates with the host computer
through an RS-232 or ot her serial interfac e protocols .
1
ωoC
----------- R1
ωoC
-----------
>>
1998 Microchip Technology Inc. DS51166C-page 79
microID™ 125
k
Hz Design Guide
3.0 microID ASK READER
The electronic circuitr y for an ASK reader is shown in
Section 4.0. The reader needs +9 VDC power supply.
The 125 kH z ca rrier sign al i s ge nerated by div idi ng th e
4 MHz time base signal that is generated by a crystal
oscill ator . A 16-st age binary ripple coun ter (74HC406 0)
is used for this purpose. The 74HC4060 also provides
a clock signal for the PIC16C84 microcontroller. The
125 kH z sign al is pas sed to an R F chok e (L 1) and fil ter
befo re i t is fed int o a p ower am pl ifi er th at i s fo r me d by
a pair of complementary bipolar transistors (Q2 and
Q3).
For long read-range applications, this power amplifier
circuit can be modifi ed. Power M OSFETs may be used
instead of the bipolar transistors (2N2222). These
power MOSFETs can be driven by +24 VDC power
supply. A push-pull predriver can be added at the front
of the complementary circuit. This modification will
enhance the signal level of the carrier signal and the
read range of the ASK Reader.
The reader circuit uses a single coil for both transmit-
ting and receiving signals. An antenna coil
(L2: 1.62 mH) and a resonant capacitor (C14: 1000 pF)
forms a series resonant circuit for a 125 kHz resonanc e
frequency. Since the C14 is grounded, the carrier signa l
(125 kHz) is filtered out to ground after passing the
antenna coil. The circuit provides a minimum
impedance at the resonance frequency. This results in
maximizing the antenna current, and therefore, the
magnetic field strength is maximized.
L2, C14, D7, C15, R24, and the other components in
the bottom part of the circuit form a signal receiving
section. D9 is a demodulator which detects the
envelope of the backscattering signal.
D9 and C15 form a half-wa ve capacit or-filtered rectifier .
The det ected en vel ope signal is charged in to C15. R24
provides a discharge path for the voltage charged in
C15. This voltage passes active filters (U5:B and C)
and the pulse shaping circuitry (U5:A) before it is fed
into the PIC16C84 for data processing.
The PIC16C8 4 microcontrol ler performs data decodin g
and communicates with the host computer via an
RS-232 serial interface.
microID™ 125
k
Hz Design Guide
DS51166C-page 80 1998 Microchip Technology Inc.
4.0 ASK READER SCHEMATIC
1998 Microchip Technology Inc. DS51166C-page 81
microID™ 125
k
Hz Design Guide
5.0 ASK READER BILL OF MATERIALS
Quantity: Part Number Part Description Reference Design
1 02-01518-D PCB ASSEMBLY DWG, microID ASK
READER
1 03-01518 SCHEMATIC, microID ASK READER
1 04-01518 PCB FAB, microID ASK READER
1 08-00161 LABEL, microID ASK
READER,U3,CHKS:C1AAh, v1.0,
ASK1.HEX
@U3
1 110-93-318-41-001 SOCKET, 18P OPEN FRAME
COLLET (0.300) xU3
1 DE9S-FRS CONN, D-SUB 9P RECPT RT ANGLE P2
1 DJ005B JACK, POWER, 2.5 mm DC PC MOUNT SP1
1 PKM22EPP-4001 BUZZER, PIEZO, 4 kHz, 3-20V BZ1
2 D47 0J25C OGHAAA C CAP, 47PF 100V
CERAMIC DISC C0G C10,C11 2 D220J20COGHAAAC CAP, 22 pF CER
DISK RAD COG 100V C1, C2
1 ECU-S1H221JCA CAP, 220pF, CER MONO, RAD, 50V, 5% C15
1 ECQ-P1102JZ CAP, 0.001uF POLYPROPYLENE 100V C17
3 ECQ-P6102JU CAP, 0.001uF POLYPROPYLENE 630V C13, C14, C16
1 ECU-S2A182JCB CAP, 1800pF MONOLITH CERM, 5%,
RAD, 100V C6
1 ECQ-V1103JM CAP, 0.01uF 100V STACK METAL FILM C9
2 ECQ-E1104KF CAP, 0.1UF 100VDC 10%
RAD METAL POLY CAP C7, C8
3 ECE-A16Z10 CAP, 10uF, ELECTRO, RAD, 16V, 20% C3, C5, C12
1 ECE-A25Z100 CAP, 100uF, ELECTRO, RAD, 25V, 20% C 4
8 1N4148 DIODE, GENERAL PURPOSE,
1N4148 (DO-35) D1-D8
1 1N4936 DIODE, 1A 400V FAST-RECOVERY
RECTIFIER D9
1 -SPARE- -SPARE- LOCATION DO NOT
INSTALL LED1,
1 78F102J INDUCTOR, 1000uH,
COATED L1
1 MCT0003-001 INDUCTOR, 1.62 µH, L2
3 2N2907A-TO18 TRANSISTOR, 2N2907A PNP,
GEN PURPOUS TO-18 Q1, Q3, Q4
1 2N2222A-TO18 TRANSISTOR, 2N2222A NPN,
GEN PURPOUS TO-18 Q2
2 5043CX10R0J RES, CF 10 OHM 1/4W 5% R10,R8
1 82E CR-1/4W-B 5% RES, CF 82 OHM 1/4W 5% R9
1 5043CX100R0J RES, CF 100 OHM 1/4W 5% R15
1 5043CX1K000J RES, CF 1K 1/4W 5% R6
3 5043CX330R0J RES, CF 330 OHM 1/4W 5% R1, R12, R14
1 5043CX470R0J RES, CF 470 OHM 5% 1/4W R4
1 1K8 CR-1/4W-B 5% RES, CF 1.8K OHM 1/4W 5% R7
1 390K CR-1/4W-T 5% RES, CF 390K-OHM,5%,1/4W R24
1 220K CR-1/4W-T 5% RES, CF 220K OHM 1/4W 5% R21
1 8K2 CR-1/4W-T 5% RES, 8.2K OHM 1/4W 5% CF R20
3 10K CR-1/4W-B 5% RES, CF 10K OHM 1/4W 5% R2, R23, R25
microID™ 125
k
Hz Design Guide
DS51166C-page 82 1998 Microchip Technology Inc.
1 5043CX47K00J RES, CF 47K 5% 1/4W R18
1 12K CR-1/4W-B 5% RES, CF 12K OHM 1/4W 5% R16
3 22K CR-1/4W-B 5% RES, CF 22K OHM 1/4W 5% R5, R11, R19
2 5043CX100K0J RES, CF 100K 5% 1/4W R13,R26
3 1M0 CR-1/4W-B 5% RES, CF 1.0M OHM 1/4W 5% R3, R17, R22
1 LM78L05ACZ IC, REG, +5V 0.1A TO-92 U1
1 MM74HC04N IC, HEX INVERTER 14P DIP U2
1 PIC16F84-10/P IC, PIC16F84 PLASTIC, 18P DIP U3
1 MM74HC4060N IC, 14 STAGE BINARY COUNTER,
16P DIP U4
1 TL084CN IC, QUAD OP AMP, 14P DIP U5
1 EFO-EC4004A4 RESONATOR, 4.00MHZ CERAMIC
W/CAP Y1
2 JS-01 SCREW, JACKSCREW, #4-40x0.416" P2
Quantity: Part Number Part Description Reference Design
1998 Microchip Technology Inc. DS51166C-page 83
microID™ 125
k
Hz Design Guide
6.0 ASK READER SOURCE CODE FOR THE PICmicro® MCU
The following source code is for the PIC16C84 microcontroller used in the ASK reader electronics.
; #=#=#=#=#=#=#=#=#=#=#= PROJECT Microchip ASK Reader =#=#=#=#=#=#=#=#=#=#=#
; v002.asm
; PIC16C84 running at 4MHz, Ti=1us
; ///////////////////////////////////////////////////////////////////////////
; Revision history
; ///////////////////////////////////////////////////////////////////////////
;
; Ver Date Comment
;
; 0.01 01 Jul 98 Copied from MCHIP\READER\FSK
; 0.02 29 Jul 98 MICROCHIP TAG HAS 128 BITS
;
; Tbit=64Tcy=512Ti
; Manchester encoded
; Microchip - Header=h’802A’ Ttag=128Tbit
; - OR -
; EM ASK - Header=b’111111111’ trailer=b’0’ Ttag=64Tbit
;
processor pic16c84
#include “p16c84.inc”
__config b’11111111101001’
; Code Protect on, power-up timer on, WDT off, XT oscillator
#define bit_CARRY STATUS,0
#define bit_ZERO STATUS,2
#define bit_RP0 STATUS,5
#define _BUZZ1 PORTA,0
#define _BUZZ2 PORTA,1
#define _RS232TX PORTA,2
#define _RS232RX PORTA,3
#define _T0CKI PORTA,4
StartPORTA = b’01100’
StartTRISA = b’11000’
BeepPort = PORTA
Beep0 = StartPORTA
Beep1 = StartPORTA | b’00001’
Beep2 = StartPORTA | b’00010’
#define _DATA_IN PORTB,0
#define _UNUSED1 PORTB,1
#define _LED2 PORTB,2
#define _LED1 PORTB,3
#define _UNUSED2 PORTB,4
#define _UNUSED3 PORTB,5
#define _UNUSED4 PORTB,6
#define _UNUSED5 PORTB,7
StartPORTB = b’00000000’
StartTRISB = b’00000001’
StartOPTION = b’10001111’ ; TMR0 internal, prescaler off
; PORTB pullups off
BO3 = h’0C’
DelayReg1 = h’0C’
Mask = h’0C’
BitCtr = h’0D’
BeepCtrHi = h’0D’
TxByte = h’0E’
BeepCtrLo = h’0E’
ParityReg1 = h’0E’
microID™ 125
k
Hz Design Guide
DS51166C-page 84 1998 Microchip Technology Inc.
Period = h’0F’
ParityReg2 = h’0F’
Buffer0 = h’10’ ; --- IMMOBILE --- IMMOBILE --- IMMOBILE --- IMMOBILE
Buffer1 = h’11’ ; |
Buffer2 = h’12’ ; |
Buffer3 = h’13’ ; |
Buffer4 = h’14’ ; |
Buffer5 = h’15’ ; |
Buffer6 = h’16’ ; |
Buffer7 = h’17’ ; |
Buffer8 = h’18’ ; |
Buffer9 = h’19’ ; |
BufferA = h’1A’ ; |
BufferB = h’1B’ ; |
BufferC = h’1C’ ; |
BufferD = h’1D’ ; |
BufferE = h’1E’ ; |
BufferF = h’1F’ ; |
Old0 = h’20’ ; |
Old1 = h’21’ ; |
Old2 = h’22’ ; |
Old3 = h’23’ ; |
Old4 = h’24’ ; |
Old5 = h’25’ ; |
Old6 = h’26’ ; |
Old7 = h’27’ ; |
Old8 = h’28’ ; |
Old9 = h’29’ ; |
OldA = h’2A’ ; |
OldB = h’2B’ ; |
OldC = h’2C’ ; |
OldD = h’2D’ ; |
OldE = h’2E’ ; |
OldF = h’2F’ ; |
SKIP macro
BTFSC PCLATH,7
endm
org h’0000’ ; *#*#*#* RESET VECTOR *#*#*#*
CLRF PCLATH
CLRF INTCON
CLRF STATUS
GOTO RESET_A
org h’0004’ ; *#*#*#* INTERRUPT VECTOR *#*#*#*
CLRF PCLATH
CLRF INTCON
CLRF STATUS
GOTO RESET_A
; ***** Subroutines, Page 0
Delay07: ;[0] Delay 7Ti
NOP ; |
Delay06: ;[0] Delay 6Ti
NOP ; |
Delay05: ;[0] Delay 5Ti
NOP ; |
Delay04: ;[0] Delay 4Ti
RETLW 0 ; |
RS232CR: ;[1] Transmit CR on RS232
MOVLW d’13’ ; |
GOTO RS232TxW ; |
1998 Microchip Technology Inc. DS51166C-page 85
microID™ 125
k
Hz Design Guide
RS232TxDigit: ;[1] Transmit LSnybble of W on RS232
ANDLW h’0F’ ; |
MOVWF TxByte ; |
MOVLW h’0A’ ; |
SUBWF TxByte,W ; |
BTFSS bit_CARRY ; |
GOTO DigitLT10 ; |
DigitGE10: ; |
MOVLW ‘A’-’0’-h’0A’ ; |
ADDWF TxByte,f ; |
DigitLT10: ; |
MOVLW ‘0’ ; |
ADDWF TxByte,W ; |
RS232TxW: ;[1] Transmit W on RS232 at 9615 baud
MOVWF TxByte ; | TxByte=W
RS232Tx: ;[1] Transmit TxByte - 104us = 9615.4 baud
BSF _RS232TX ; | Stop bit
MOVLW d’35’ ; | |
MOVLW DelayReg1 ; | |
RS232TxD1: ; | |
DECFSZ DelayReg1,f ; | |
GOTO RS232TxD1 ; | |
BCF _RS232TX ; | Start bit
NOP ; | |
MOVLW d’32’ ; | |
MOVWF DelayReg1 ; | |
RS232TxD2: ; | |
DECFSZ DelayReg1,f ; | |
GOTO RS232TxD2 ; | |
CLRF BitCtr ; | BitCtr=#8
BSF BitCtr,3 ; | |
RS232TxL1: ; | {% -4Ti
BTFSC TxByte,0 ; | Transmit TxByte.0, RR TxByte
GOTO RS232TxBit1 ; | |
NOP ; | |
RS232TxBit0: ; | |
BCF _RS232TX ; | |
BCF bit_CARRY ; | |
GOTO RS232TxBitDone ; | |
RS232TxBit1: ; | |
BSF _RS232TX ; | |
BSF bit_CARRY ; | |
GOTO RS232TxBitDone ; | |
RS232TxBitDone: ; | |
RRF TxByte,f ; | |% 4Ti
MOVLW d’30’ ; | delay 1 bit
MOVWF DelayReg1 ; | |
GOTO RS232TxD3 ; | |
RS232TxD3: ; | |
DECFSZ DelayReg1,f ; | |
GOTO RS232TxD3 ; | |
DECFSZ BitCtr,f ; | DEC BitCtr
GOTO RS232TxL1 ; | } until (BitCtr==#0)
CALL Delay04 ; | delay
BSF _RS232TX ; | stop bit
RETLW 0 ; end
ParityCheck: ;[0] Check parity
CLRF ParityReg1 ; | ParityReg1=0
MOVLW d’10’ ; | BitCtr=10
MOVWF BitCtr ; | |
ParityL1: ; | {
CLRF ParityReg2 ; | ParityReg2=0
MOVLW h’10’ ; | Mask=h’10’
MOVWF Mask ; | |
ParityL2: ; | {
microID™ 125
k
Hz Design Guide
DS51166C-page 86 1998 Microchip Technology Inc.
BCF bit_CARRY ; | LSL Buffer0-7
RLF Buffer0,f ; | |
RLF Buffer1,f ; | |
RLF Buffer2,f ; | |
RLF Buffer3,f ; | |
RLF Buffer4,f ; | |
RLF Buffer5,f ; | |
RLF Buffer6,f ; | |
RLF Buffer7,f ; | |
BTFSC Buffer6,7 ; | if (Buffer6.7==1)
INCF ParityReg2,f ; | { INC ParityReg2 }
MOVF Mask,W ; | W=Mask
BTFSC Buffer6,7 ; | if (Buffer6.7==1)
XORWF ParityReg1,f ; | { ParityReg1=ParityReg1 XOR W }
BCF bit_CARRY ; | LSR Mask
RRF Mask,f ; | |
BTFSS bit_CARRY ; | } until (bit_CARRY==1)
GOTO ParityL2 ; | |
BTFSC ParityReg2,0 ; | if (ParityReg2.0==1)
GOTO ParityBad ; | { goto ParityBad }
DECFSZ BitCtr,f ; | DEC BitCtr
GOTO ParityL1 ; | } until (BitCtr==0)
MOVLW h’10’ ; | Mask=h’10’
MOVWF Mask ; | |
ParityL3: ; | {
BCF bit_CARRY ; | LSL Buffer0-7
RLF Buffer0,f ; | |
RLF Buffer1,f ; | |
RLF Buffer2,f ; | |
RLF Buffer3,f ; | |
RLF Buffer4,f ; | |
RLF Buffer5,f ; | |
RLF Buffer6,f ; | |
RLF Buffer7,f ; | |
MOVF Mask,W ; | W=Mask
BTFSC Buffer6,7 ; | if (Buffer6.7==1)
XORWF ParityReg1,f ; | { ParityReg1=ParityReg1 XOR W }
BCF bit_CARRY ; | LSR Mask
RRF Mask,f ; | |
BTFSS Mask,0 ; | } until (Mask.0==1)
GOTO ParityL3 ; | |
MOVF ParityReg1,W ; | if ((ParityReg1 AND h’1E’)!=0)
ANDLW h’1E’ ; | |
BTFSS bit_ZERO ; | |
GOTO ParityBad ; | { goto ParityBad }
ParityGood: ; |
MOVF BufferF,W ; | Buffer0-7=Buffer8-F
MOVWF Buffer7 ; | |
MOVF BufferE,W ; | |
MOVWF Buffer6 ; | |
MOVF BufferD,W ; | |
MOVWF Buffer5 ; | |
MOVF BufferC,W ; | |
MOVWF Buffer4 ; | |
MOVF BufferB,W ; | |
MOVWF Buffer3 ; | |
MOVF BufferA,W ; | |
MOVWF Buffer2 ; | |
MOVF Buffer9,W ; | |
MOVWF Buffer1 ; | |
MOVF Buffer8,W ; | |
MOVWF Buffer0 ; | |
BCF bit_CARRY ; | bit_CARRY=0
RETLW 0 ; |
ParityBad: ; |
MOVF BufferF,W ; | Buffer0-7=Buffer8-F
1998 Microchip Technology Inc. DS51166C-page 87
microID™ 125
k
Hz Design Guide
MOVWF Buffer7 ; | |
MOVF BufferE,W ; | |
MOVWF Buffer6 ; | |
MOVF BufferD,W ; | |
MOVWF Buffer5 ; | |
MOVF BufferC,W ; | |
MOVWF Buffer4 ; | |
MOVF BufferB,W ; | |
MOVWF Buffer3 ; | |
MOVF BufferA,W ; | |
MOVWF Buffer2 ; | |
MOVF Buffer9,W ; | |
MOVWF Buffer1 ; | |
MOVF Buffer8,W ; | |
MOVWF Buffer0 ; | |
BSF bit_CARRY ; | bit_CARRY=1
RETLW 0 ; |
; ***** End of subroutines, Page 0
RESET_A:
CLRWDT
; Initialise registers
CLRF STATUS ; | Access register page 0
CLRF FSR ; | FSR=#0
MOVLW StartPORTA ; | Initialise PORT and TRIS registers
MOVWF PORTA ; | |
MOVLW StartPORTB ; | |
MOVWF PORTB ; | |
BSF bit_RP0 ;^| |
MOVLW StartTRISA ;^| |
MOVWF TRISA ;^| |
MOVLW StartTRISB ;^| |
MOVWF TRISB ;^| |
MOVLW StartOPTION ;^| Initialise OPTION register
MOVWF OPTION_REG ;^| |
BCF bit_RP0 ; | |
CLRF Old0 ; | Clear Old buffer
CLRF Old1 ; | |
CLRF Old2 ; | |
CLRF Old3 ; | |
CLRF Old4 ; | |
CLRF Old5 ; | |
CLRF Old6 ; | |
CLRF Old7 ; | |
BigLoop1:
BSF _LED1 ; LEDs “reading”
CALL Delay07 ; |
BCF _LED2 ; |
MOVLW h’09’ ; Transmit TAB regularly
CALL RS232TxW ; |
MOVLW d’128’ ; set BitCtr
MOVWF BitCtr ; |
GetEdge: ; Get an edge on _DATA_IN
BTFSC _DATA_IN ; |
GOTO PreSync_H0 ; |
NOP ; |
PreSync_L0: ; |% 3 from low sample
NOP ; |
BTFSC _DATA_IN ; |
GOTO PreSync_H0 ; |
CLRF Period ; | Period=0
PreSync_L1: ; | { % 7+Period*8 from low sample
INCF Period,f ; | INC Period
microID™ 125
k
Hz Design Guide
DS51166C-page 88 1998 Microchip Technology Inc.
BTFSC Period,6 ; | if ((Period*8Ti)>=Tbit*1.25=512Ti*1.25=640Ti)
BTFSS Period,4 ; | |
SKIP ; | |
GOTO BigLoop1 ; | { goto BigLoop1 }
BTFSS _DATA_IN ; | } until (_DATA_IN==1)
GOTO PreSync_L1 ; | |
; |% 6+Period*8 from low sample
; |% 6 from rise
MOVLW d’48’ ; | if ((Period*8)>=Tbit*0.75=512Ti*0.75=384Ti)
SUBWF Period,W ; | |
BTFSC bit_CARRY ; | |
GOTO Sync_Done ; | { goto Sync_Done }
; |% 10 from rise
CALL Delay05 ; | delay
DoSync_H: ; |% 15 from rise
MOVLW d’2’ ; | Period=2
MOVWF Period ; | |
CALL Delay04 ; | delay
GOTO DoSync_HL ; | |
DoSync_HL: ; | {% 7+Period*8 from rise
INCF Period,f ; | INC Period
BTFSC Period,6 ; | if ((Period*8Ti)>=Tbit*1.25=512Ti*1.25=640Ti)
BTFSS Period,4 ; | |
SKIP ; | |
GOTO BigLoop1 ; | { goto BigLoop1 }
BTFSC _DATA_IN ; | } until (_DATA_IN==0)
GOTO DoSync_HL ; | |
; |% 6+Period*8 from rise
; |% 6 from fall
MOVLW d’16’ ; | if ((Period*8Ti)<Tbit*0.25=512Ti*0.25=128Ti)
SUBWF Period,W ; | |
BTFSS bit_CARRY ; | |
GOTO BigLoop1 ; | { goto BigLoop1 }
; |% 10 from fall
MOVLW d’48’ ; | if ((Period*8Ti)<Tbit*0.75=512Ti*0.75=384Ti)
SUBWF Period,W ; | |
BTFSS bit_CARRY ; | |
GOTO DoSync_L ; | { goto DoSync_L }
GOTO Sync_Done ; | goto Sync_Done
PreSync_H0: ; |% 3 from high sample
NOP ; |
BTFSS _DATA_IN ; |
GOTO PreSync_L0 ; |
CLRF Period ; | Period=0
PreSync_H1: ; | {% 7+Period*8 from high sample
INCF Period,f ; | INC Period
BTFSC Period,6 ; | if ((Period*8Ti)>=Tbit*1.25=512Ti*1.25=640Ti)
BTFSS Period,4 ; | |
SKIP ; | |
GOTO BigLoop1 ; | { goto BigLoop1 }
BTFSC _DATA_IN ; | } until (_DATA_IN==0)
GOTO PreSync_H1 ; | |
; |% 6+Period*8 from high sample
; |% 6 from fall
MOVLW d’48’ ; | if ((Period*8Ti)>=Tbit*0.75=512Ti*0.75=384Ti)
SUBWF Period,W ; | |
BTFSC bit_CARRY ; | |
GOTO Sync_Done ; | { goto Sync_Done }
; |% 10 from fall
CALL Delay05 ; | delay
DoSync_L: ; |% 15 from fall
MOVLW d’2’ ; | Period=2
MOVWF Period ; | |
CALL Delay04 ; | delay
GOTO DoSync_LL ; | |
1998 Microchip Technology Inc. DS51166C-page 89
microID™ 125
k
Hz Design Guide
DoSync_LL: ; | {% 7+Period*8 from fall
INCF Period,f ; | INC Period
BTFSC Period,6 ; | if ((Period*8Ti)>=Tbit*1.25=512Ti*1.25=640Ti)
BTFSS Period,4 ; | |
SKIP ; | |
GOTO BigLoop1 ; | { goto BigLoop1 }
BTFSS _DATA_IN ; | } until (_DATA_IN==1)
GOTO DoSync_LL ; | |
; |% 6+Period*8 from fall
; |% 6 from rise
MOVLW d’16’ ; | if ((Period*8Ti)<Tbit*0.25=512Ti*0.25=128Ti)
SUBWF Period,W ; | |
BTFSS bit_CARRY ; | |
GOTO BigLoop1 ; | { goto BigLoop1 }
; |% 10 from rise
MOVLW d’48’ ; | if ((Period*8Ti)<Tbit*0.75=512Ti*0.75=384Ti)
SUBWF Period,W ; | |
BTFSS bit_CARRY ; | |
GOTO DoSync_H ; | { goto DoSync_H }
GOTO Sync_Done ; goto Sync_Done
Sync_Done: ; |% 16 from edge
; |% -368 from sample
MOVLW d’121’ ; | DelayReg1=121
MOVWF DelayReg1 ; | |
NOP ; | delay
ReadBit: ; {% -2-DelayReg1*3 Ti from sample
ReadBitD1: ; delay
DECFSZ DelayReg1,f ; |
GOTO ReadBitD1 ; |
CLRF BO3 ; BO3.1=_DATA_IN
BTFSC _DATA_IN ; |
INCF BO3,f ; |% effective sample time
BTFSC _DATA_IN ; |
INCF BO3,f ; |
BTFSC _DATA_IN ; |
INCF BO3,f ; |
BCF bit_CARRY ; bit_CARRY=BO3.1
BTFSC BO3,1 ; |
BSF bit_CARRY ; |
RLF Buffer0,f ; roll in bit_CARRY
RLF Buffer1,f ; |
RLF Buffer2,f ; |
RLF Buffer3,f ; |
RLF Buffer4,f ; |
RLF Buffer5,f ; |
RLF Buffer6,f ; |
RLF Buffer7,f ; |
RLF Buffer8,f ; |
RLF Buffer9,f ; |
RLF BufferA,f ; |
RLF BufferB,f ; |
RLF BufferC,f ; |
RLF BufferD,f ; |
RLF BufferE,f ; |
RLF BufferF,f ; |% 23 from sample
; |% -233 from sample
MOVLW d’76’ ; delay 230Ti
MOVWF DelayReg1 ; |
NOP ; |
ReadBitD2: ; |
DECFSZ DelayReg1,f ; |
GOTO ReadBitD2 ; |
; |% -3 from sample
CLRF BO3 ; BO3.1=_DATA_IN
BTFSC _DATA_IN ; |
microID™ 125
k
Hz Design Guide
DS51166C-page 90 1998 Microchip Technology Inc.
INCF BO3,f ; |% effective sample time
BTFSC _DATA_IN ; |
INCF BO3,f ; |
BTFSC _DATA_IN ; |
INCF BO3,f ; |
BTFSC Buffer0,0 ; BO3.1=BO3.1 XOR Buffer0.0
COMF BO3,f ; |
BTFSS BO3,1 ; if (BO3.1==0)
GOTO BigLoop1 ; { goto BigLoop1 }
; % 8 from sample
; % -248 from sample
MOVLW d’80’ ; DelayReg1=80
MOVWF DelayReg1 ; |
NOP ; delay
; % -5-DelayReg1*3 Ti from sample
DECFSZ BitCtr,f ; DEC BitCtr
GOTO ReadBit ; } until (BitCtr==#0)
HeadSearch1:
MOVLW d’128’ ; set BitCtr
MOVWF BitCtr ; |
HeadSearch1L1: ; {
MOVF BufferF,W ; if (header found)
XORLW h’80’ ; |
BTFSS bit_ZERO ; |
GOTO NotHead1A ; |
MOVF BufferE,W ; |
XORLW h’2A’ ; |
BTFSS bit_ZERO ; |
GOTO NotHead1A ; {
GOTO HeadFound0 ; goto HeadFound0
NotHead1A: ; }
MOVF BufferF,W ; if (inverse header found)
XORLW h’7F’ ; |
BTFSS bit_ZERO ; |
GOTO NotHead1B ; |
MOVF BufferE,W ; |
XORLW h’D5’ ; |
BTFSS bit_ZERO ; |
GOTO NotHead1B ; {
GOTO HeadFound1 ; goto HeadFound1
NotHead1B: ; }
RLF Buffer0,f ; ROL Buffer
RLF Buffer1,f ; |
RLF Buffer2,f ; |
RLF Buffer3,f ; |
RLF Buffer4,f ; |
RLF Buffer5,f ; |
RLF Buffer6,f ; |
RLF Buffer7,f ; |
RLF Buffer8,f ; |
RLF Buffer9,f ; |
RLF BufferA,f ; |
RLF BufferB,f ; |
RLF BufferC,f ; |
RLF BufferD,f ; |
RLF BufferE,f ; |
RLF BufferF,f ; |
BCF Buffer0,0 ; |
BTFSC bit_CARRY ; |
BSF Buffer0,0 ; |
DECFSZ BitCtr,f ; DEC BitCtr
GOTO HeadSearch1L1 ; } until (BitCtr==#0)
MOVF Buffer0,W ; if ((Buffer0-7)!=(Buffer8-F)) { goto BigLoop1 }
XORWF Buffer8,W ; |
1998 Microchip Technology Inc. DS51166C-page 91
microID™ 125
k
Hz Design Guide
BTFSS bit_ZERO ; |
GOTO BigLoop1 ; |
MOVF Buffer1,W ; |
XORWF Buffer9,W ; |
BTFSS bit_ZERO ; |
GOTO BigLoop1 ; |
MOVF Buffer2,W ; |
XORWF BufferA,W ; |
BTFSS bit_ZERO ; |
GOTO BigLoop1 ; |
MOVF Buffer3,W ; |
XORWF BufferB,W ; |
BTFSS bit_ZERO ; |
GOTO BigLoop1 ; |
MOVF Buffer4,W ; |
XORWF BufferC,W ; |
BTFSS bit_ZERO ; |
GOTO BigLoop1 ; |
MOVF Buffer5,W ; |
XORWF BufferD,W ; |
BTFSS bit_ZERO ; |
GOTO BigLoop1 ; |
MOVF Buffer6,W ; |
XORWF BufferE,W ; |
BTFSS bit_ZERO ; |
GOTO BigLoop1 ; |
MOVF Buffer7,W ; |
XORWF BufferF,W ; |
BTFSS bit_ZERO ; |
GOTO BigLoop1 ; |
HeadSearch2:
MOVLW d’64’ ; set BitCtr
MOVWF BitCtr ; |
HeadSearch2L1: ; {
MOVF BufferF,W ; if (header found)
XORLW h’FF’ ; |
BTFSS bit_ZERO ; |
GOTO NotHead2A ; |
BTFSS BufferE,7 ; |
GOTO NotHead2A ; |
BTFSC Buffer8,0 ; |
GOTO NotHead2A ; {
GOTO HeadFound2 ; goto HeadFound2
NotHead2A: ; }
RLF Buffer0,f ; ROL Buffer
RLF Buffer1,f ; |
RLF Buffer2,f ; |
RLF Buffer3,f ; |
RLF Buffer4,f ; |
RLF Buffer5,f ; |
RLF Buffer6,f ; |
RLF Buffer7,f ; |
RLF Buffer8,f ; |
RLF Buffer9,f ; |
RLF BufferA,f ; |
RLF BufferB,f ; |
RLF BufferC,f ; |
RLF BufferD,f ; |
RLF BufferE,f ; |
RLF BufferF,f ; |
BCF Buffer0,0 ; |
BTFSC bit_CARRY ; |
BSF Buffer0,0 ; |
DECFSZ BitCtr,f ; DEC BitCtr
GOTO HeadSearch2L1 ; } until (BitCtr==#0)
microID™ 125
k
Hz Design Guide
DS51166C-page 92 1998 Microchip Technology Inc.
HeadSearch3:
MOVLW d’64’ ; set BitCtr
MOVWF BitCtr ; |
HeadSearch3L1: ; {
MOVF BufferF,W ; if (header found)
XORLW h’00’ ; |
BTFSS bit_ZERO ; |
GOTO NotHead3A ; |
BTFSC BufferE,7 ; |
GOTO NotHead3A ; |
BTFSS Buffer8,0 ; |
GOTO NotHead3A ; {
GOTO HeadFound3 ; goto HeadFound3
NotHead3A: ; }
RLF Buffer0,f ; ROL Buffer
RLF Buffer1,f ; |
RLF Buffer2,f ; |
RLF Buffer3,f ; |
RLF Buffer4,f ; |
RLF Buffer5,f ; |
RLF Buffer6,f ; |
RLF Buffer7,f ; |
RLF Buffer8,f ; |
RLF Buffer9,f ; |
RLF BufferA,f ; |
RLF BufferB,f ; |
RLF BufferC,f ; |
RLF BufferD,f ; |
RLF BufferE,f ; |
RLF BufferF,f ; |
BCF Buffer0,0 ; |
BTFSC bit_CARRY ; |
BSF Buffer0,0 ; |
DECFSZ BitCtr,f ; DEC BitCtr
GOTO HeadSearch3L1 ; } until (BitCtr==#0)
GOTO BigLoop1 ; goto BigLoop1
HeadFound3:
COMF BufferF,f
COMF BufferE,f
COMF BufferD,f
COMF BufferC,f
COMF BufferB,f
COMF BufferA,f
COMF Buffer9,f
COMF Buffer8,f
COMF Buffer7,f
COMF Buffer6,f
COMF Buffer5,f
COMF Buffer4,f
COMF Buffer3,f
COMF Buffer2,f
COMF Buffer1,f
COMF Buffer0,f
CALL ParityCheck
BTFSC bit_CARRY
GOTO BigLoop1
GOTO CheckSame
HeadFound2:
CALL ParityCheck
BTFSC bit_CARRY
GOTO HeadSearch3
GOTO CheckSame
1998 Microchip Technology Inc. DS51166C-page 93
microID™ 125
k
Hz Design Guide
HeadFound1:
COMF BufferF,f
COMF BufferE,f
COMF BufferD,f
COMF BufferC,f
COMF BufferB,f
COMF BufferA,f
COMF Buffer9,f
COMF Buffer8,f
COMF Buffer7,f
COMF Buffer6,f
COMF Buffer5,f
COMF Buffer4,f
COMF Buffer3,f
COMF Buffer2,f
COMF Buffer1,f
COMF Buffer0,f
HeadFound0:
CheckSame: ; if (Buffer!=Old) { goto NotSame }
MOVF Buffer0,W ; |
XORWF Old0,W ; |
BTFSS bit_ZERO ; |
GOTO NotSame ; |
MOVF Buffer1,W ; |
XORWF Old1,W ; |
BTFSS bit_ZERO ; |
GOTO NotSame ; |
MOVF Buffer2,W ; |
XORWF Old2,W ; |
BTFSS bit_ZERO ; |
GOTO NotSame ; |
MOVF Buffer3,W ; |
XORWF Old3,W ; |
BTFSS bit_ZERO ; |
GOTO NotSame ; |
MOVF Buffer4,W ; |
XORWF Old4,W ; |
BTFSS bit_ZERO ; |
GOTO NotSame ; |
MOVF Buffer5,W ; |
XORWF Old5,W ; |
BTFSS bit_ZERO ; |
GOTO NotSame ; |
MOVF Buffer6,W ; |
XORWF Old6,W ; |
BTFSS bit_ZERO ; |
GOTO NotSame ; |
MOVF Buffer7,W ; |
XORWF Old7,W ; |
BTFSS bit_ZERO ; |
GOTO NotSame ; |
MOVF Buffer8,W ; |
XORWF Old8,W ; |
BTFSS bit_ZERO ; |
GOTO NotSame ; |
MOVF Buffer9,W ; |
XORWF Old9,W ; |
BTFSS bit_ZERO ; |
GOTO NotSame ; |
MOVF BufferA,W ; |
XORWF OldA,W ; |
BTFSS bit_ZERO ; |
GOTO NotSame ; |
MOVF BufferB,W ; |
microID™ 125
k
Hz Design Guide
DS51166C-page 94 1998 Microchip Technology Inc.
XORWF OldB,W ; |
BTFSS bit_ZERO ; |
GOTO NotSame ; |
MOVF BufferC,W ; |
XORWF OldC,W ; |
BTFSS bit_ZERO ; |
GOTO NotSame ; |
MOVF BufferD,W ; |
XORWF OldD,W ; |
BTFSS bit_ZERO ; |
GOTO NotSame ; |
MOVF BufferE,W ; |
XORWF OldE,W ; |
BTFSS bit_ZERO ; |
GOTO NotSame ; |
MOVF BufferF,W ; |
XORWF OldF,W ; |
BTFSS bit_ZERO ; |
GOTO NotSame ; |
Same:
TxTag: ;- Transmit tag
BSF _LED2 ; LEDs “Found tag”
CALL Delay07 ; |
BCF _LED1 ; |
MOVLW d’4’ ; Beep at 3597Hz for 1024 cycles
MOVWF BeepCtrHi ; |
MOVLW d’0’ ; |
MOVWF BeepCtrLo ; |
BeepLoopJ1: ; |
GOTO BeepLoopJ2 ; |
BeepLoopJ2: ; |
MOVLW Beep1 ; |
MOVWF BeepPort ; |
MOVLW d’34’ ; |
MOVWF DelayReg1 ; |
BeepD1: ; |
CLRWDT ; |
DECFSZ DelayReg1,f ; |
GOTO BeepD1 ; |
MOVLW Beep2 ; |
MOVWF BeepPort ; |
MOVLW d’32’ ; |
MOVWF DelayReg1 ; |
NOP ; |
GOTO BeepD2 ; |
BeepD2: ; |
CLRWDT ; |
DECFSZ DelayReg1,f ; |
GOTO BeepD2 ; |
DECFSZ BeepCtrLo,f ; |
GOTO BeepLoopJ1 ; |
DECFSZ BeepCtrHi,f ; |
GOTO BeepLoopJ2 ; |
NOP ; |
MOVLW Beep0 ; |
MOVWF BeepPort ; |
MOVF OldF,W
MOVWF BufferF
MOVF OldE,W
MOVWF BufferE
MOVF OldD,W
MOVWF BufferD
MOVF OldC,W
1998 Microchip Technology Inc. DS51166C-page 95
microID™ 125
k
Hz Design Guide
MOVWF BufferC
MOVF OldB,W
MOVWF BufferB
MOVF OldA,W
MOVWF BufferA
MOVF Old9,W
MOVWF Buffer9
MOVF Old8,W
MOVWF Buffer8
MOVF Old7,W
MOVWF Buffer7
MOVF Old6,W
MOVWF Buffer6
MOVF Old5,W
MOVWF Buffer5
MOVF Old4,W
MOVWF Buffer4
MOVF Old3,W
MOVWF Buffer3
MOVF Old2,W
MOVWF Buffer2
MOVF Old1,W
MOVWF Buffer1
MOVF Old0,W
MOVWF Buffer0
CALL RS232CR ; Transmit tag info
MOVLW ‘A’ ; |
CALL RS232TxW ; |
MOVLW ‘S’ ; |
CALL RS232TxW ; |
MOVLW ‘K’ ; |
CALL RS232TxW ; |
CALL RS232CR ; |
MOVLW ‘T’ ; |
CALL RS232TxW ; |
MOVLW ‘b’ ; |
CALL RS232TxW ; |
MOVLW ‘i’ ; |
CALL RS232TxW ; |
MOVLW ‘t’ ; |
CALL RS232TxW ; |
MOVLW ‘=’ ; |
CALL RS232TxW ; |
MOVLW ‘6’ ; |
CALL RS232TxW ; |
MOVLW ‘4’ ; |
CALL RS232TxW ; |
MOVLW ‘T’ ; |
CALL RS232TxW ; |
MOVLW ‘c’ ; |
CALL RS232TxW ; |
MOVLW ‘y’ ; |
CALL RS232TxW ; |
CALL RS232CR ; |
MOVLW ‘C’ ; |
CALL RS232TxW ; |
MOVLW ‘o’ ; |
CALL RS232TxW ; |
MOVLW ‘n’ ; |
CALL RS232TxW ; |
MOVLW ‘s’ ; |
CALL RS232TxW ; |
MOVLW ‘t’ ; |
CALL RS232TxW ; |
MOVLW ‘a’ ; |
microID™ 125
k
Hz Design Guide
DS51166C-page 96 1998 Microchip Technology Inc.
CALL RS232TxW ; |
MOVLW ‘n’ ; |
CALL RS232TxW ; |
MOVLW ‘t’ ; |
CALL RS232TxW ; |
CALL RS232CR ; |
MOVLW ‘T’ ; |
CALL RS232TxW ; |
MOVLW ‘t’ ; |
CALL RS232TxW ; |
MOVLW ‘a’ ; |
CALL RS232TxW ; |
MOVLW ‘g’ ; |
CALL RS232TxW ; |
MOVLW ‘=’ ; |
CALL RS232TxW ; |
MOVF BufferF,W ; |
XORLW h’80’ ; |
BTFSS bit_ZERO ; |
GOTO Ttag64 ; |
Ttag128: ; |
MOVLW ‘1’ ; |
CALL RS232TxW ; |
MOVLW ‘2’ ; |
CALL RS232TxW ; |
MOVLW ‘8’ ; |
CALL RS232TxW ; |
GOTO TtagJ1 ; |
Ttag64: ; |
MOVLW ‘6’ ; |
CALL RS232TxW ; |
MOVLW ‘4’ ; |
CALL RS232TxW ; |
GOTO TtagJ1 ; |
TtagJ1: ; |
MOVLW ‘T’ ; |
CALL RS232TxW ; |
MOVLW ‘b’ ; |
CALL RS232TxW ; |
MOVLW ‘i’ ; |
CALL RS232TxW ; |
MOVLW ‘t’ ; |
CALL RS232TxW ; |
CALL RS232CR ; |
MOVLW ‘P’ ; |
CALL RS232TxW ; |
MOVLW ‘o’ ; |
CALL RS232TxW ; |
MOVLW ‘l’ ; |
CALL RS232TxW ; |
MOVLW ‘a’ ; |
CALL RS232TxW ; |
MOVLW ‘r’ ; |
CALL RS232TxW ; |
MOVLW ‘i’ ; |
CALL RS232TxW ; |
MOVLW ‘t’ ; |
CALL RS232TxW ; |
MOVLW ‘y’ ; |
CALL RS232TxW ; |
MOVLW ‘ ‘ ; |
CALL RS232TxW ; |
MOVLW ‘0’ ; |
CALL RS232TxW ; |
CALL RS232CR ; |
MOVLW BufferF ; Transmit tag ID
1998 Microchip Technology Inc. DS51166C-page 97
microID™ 125
k
Hz Design Guide
MOVWF FSR ; |
MOVF BufferF,W ; |
XORLW h’80’ ; |
BTFSC bit_ZERO ; |
GOTO TxLoop1 ; |
MOVLW Buffer7 ; |
MOVWF FSR ; |
TxLoop1: ; |
SWAPF INDF,W ; |
CALL RS232TxDigit ; |
MOVF INDF,W ; |
CALL RS232TxDigit ; |
DECF FSR,f ; |
BTFSC FSR,4 ; |
GOTO TxLoop1 ; |
CALL RS232CR ; |
GOTO BigLoop1 ; goto BigLoop1
NotSame: ; Old=Data
MOVF Buffer0,W ; |
MOVWF Old0 ; |
MOVF Buffer1,W ; |
MOVWF Old1 ; |
MOVF Buffer2,W ; |
MOVWF Old2 ; |
MOVF Buffer3,W ; |
MOVWF Old3 ; |
MOVF Buffer4,W ; |
MOVWF Old4 ; |
MOVF Buffer5,W ; |
MOVWF Old5 ; |
MOVF Buffer6,W ; |
MOVWF Old6 ; |
MOVF Buffer7,W ; |
MOVWF Old7 ; |
MOVF Buffer8,W ; |
MOVWF Old8 ; |
MOVF Buffer9,W ; |
MOVWF Old9 ; |
MOVF BufferA,W ; |
MOVWF OldA ; |
MOVF BufferB,W ; |
MOVWF OldB ; |
MOVF BufferC,W ; |
MOVWF OldC ; |
MOVF BufferD,W ; |
MOVWF OldD ; |
MOVF BufferE,W ; |
MOVWF OldE ; |
MOVF BufferF,W ; |
MOVWF OldF ; |
GOTO BigLoop1 ; goto BigLoop1
end
microID™ 125
k
Hz Design Guide
DS51166C-page 98 1998 Microchip Technology Inc.
NOTES:
1998 Microchip Technology Inc. DS51167B-page 99
MmicroID™ 125 kHz DESIGN GUIDE
1.0 INTRODUCTION
When more than one tag is in the same RF field of a
reader, each tag will transmit data at the same time.
This results in data collision at the receiving end of the
reader. No correct dec isio n can be made b ased on this
data. The re ader mus t receiv e data from a tag at a time
for correct data processing.
The anticollision device (MCRF250) is designed to
send FSK data to reader without data collision, and it
must be read by an anticollision reader. This type of
device can be effectively used in inventory and asset
control applications where mult ipl e tags are read in th e
same RF field. The anticollision algorithm of the device
is explained in the
MCRF250 Data Sheet
, page 15.
This app licat ion note is w ritten as a re ference guide for
anticollision reader designers. The anticollision reader
is designed to provide correct signals to the
anticollision device (MCRF250) to perform an anticolli-
sion action during operation.
Microchip Technology Inc. provides basic anticollision
FSK reader electronic circuitry for the MCRF250
customers as a par t of this design guide. The microID
Anticollis ion R ead er (d em o un it), t hat c an rea d 10 tag s
or more in the same RF field, is available in the microID
Developers Kit (DV103002). An electronic copy of the
microID PICmicro® sour ce code is also available u pon
request.
FIGURE 1-1: BLOCK DIAGRAM OF TYPICAL RFID READER FOR FSK SIGNAL (125 kHz)
(4 MHz Crystal Oscillator) Carrier Signal Amplifier
(Power Driver)
Env elope Detector
Interface with
Host Computer
Transmitting Section
Antenna Coil
CLK
To Host Computer
Serial Interface (RS-232)
125 kHz
Time Base Signal Generator
Microcontroller
Data Decoding
Receiving Section
÷ 32
Signal Collision
Detector
Gap Signal Gate
Filter/Amplifier
Pulse Waveform Shaping
Data
FSK Anticollision Reader Reference Design
PICmicro is a registered tradmark of Microchip Technology Inc.
microID™ 125
k
Hz Design Guide
DS51167B-page 100 1998 Microchip Technology Inc.
2.0 READER CIRCUITS
The anti colli si on RFID reader consi sts o f a tra nsmi tting
and a receiving section. The transmitting section
includ es a carrier frequen cy generat or , gap sign al gate,
and an antenna circuit. The receiving section includes
peak detector, signal amplifier/filter, signal collision
detector, and the microcontroller for data processing.
The reader also communicates with an external host
computer. A basic block diagram of the typical RFID
reader is shown in Figure 1-1.
The electronic circuitry for an anticollision FSK reader
is shown in Section 3.0. The reader needs a +9 VDC
power su pply.
The 125 kH z ca rrier sign al i s ge nerated by div idi ng th e
4 MHz time base signal that is generated by a crystal
oscill ator . A 16-st age binary ripple coun ter (74HC406 0)
is used for this purpose. The 74HC4060 also provides
a clock signal for the PIC16C84 microcontroller. The
125 kHz signal from Pin no. 5 of U6 is fed into U2 (Nor
gate) and two stage power amplifiers that are formed
by U4, Q1, and Q2.
The 125 kHz signal from Q1 and Q2 is fed into the
antenna circui t formed by L1(1.62 mH) and C22 (1000
pF). L1 an d C22 form a series resonant c ircuit for a 125
kHz resonance frequency. Since the C22 is grounded,
the carrier signal (125 kHz) is filtered out to ground
after passing the antenna coil. The circuit provides a
mini mum impedan c e at the resonance frequency. This
results in maximizing the antenna current, and
therefore, the magnetic field strength is maximized.
The gap signal from Pin no. 7 of U7 (Microcontroller)
controls the 125 KHz antenna driver circuit (Q1 and
Q2). Q1 and Q2 are turned off during the gap signal
“high”. There is no RF signal at the antenna coil during
this gap period.
The reader circuit uses a single coil for both transmit-
ting and receiving signals. L1, C22, D8, and the other
components in the bottom parts of the circuit form a
signal receiving section.
In the FSK communication protocol, a ‘0’ and a ‘1’ are
represented by two different frequencies. In the
MCRF250, a ‘0’ and a ‘1’ are represented by Fc/8 and
Fc/10, respectively. Fc is the carrier frequency. The
MCRF250 sends this FSK signal to the reader by an
amplitude modulation of the carrier signal.
The demodulation is accomplished by detecting the
envelope of the carrier signal. A half-wave
capacitor-filtered rectifier circuit (D8, D9, and C26) is
used f or the d emodulation p rocess. The det ected en ve-
lope sig nal is charged in to the C26. R37 pro vides a dis-
charge path for the voltage charged in the C26. This
voltage passes active filters (U10:A,C ,D) and the pulse
shaping circuitry (U10:B) before it is fed into the
PIC16C84 for data processing. U10 (A,D,C) forms a
bandpass filter for 12 kHz – 16 kHz signals.
When m ore t han o ne tag are tr a ns mittin g data at sam e
time, there will be wobbles in data signals in the
receiver. This wobble is detected in U8. If the wobble
occurs, c10 becomes fully charged. This will set CLK
input of US:B, and results in a logic “LOW” in Q of the
U5:B. T he m ic r oc on t ol l er (U7) d e tects t h e l o gi c “LOW”
and turns on the ga p c on trol ga te (U5:A) t o s en d a ga p
signla to the tags.
The PIC16C84 microcontroller performs data decod-
ing, provides gap timing signals, and communicates
with the host computer via an RS-232 serial interface.
FIGURE 2-1: RFID FSK ANTICOLLISION WINDOW
1998 Microchip Technology Inc. DS51167B-page 101
microID™ 125
k
Hz Design Guide
FIGURE 2-2: ANTICOLLISION ALGORITHM FOR A MCRF250 READER
Modulation
Gap Carrier
Wait 5 bit times
Field On
Yes
No Present?
60 µSec
Gap Carrier
60 µSec
Modulation
Present?
Data
Read
Collision?
tag data
Verify Header
and Data?
Gap Carrier
1st half bit 1
Yes
No
No
Yes
No
Yes
microID™ 125
k
Hz Design Guide
DS51167B-page 102 1998 Microchip Technology Inc.
3.0 ANTICOLLISION READER SCHEMATIC
D7
1N4148
D5
1N4148
C27
470uF, 16V
1N4936
D8
U10:B
7
+5
-6
MC34084
U10:A
1
+3
-2
+5V
Q1
IRF9520
Q4
2N7000
U2:B
4
6
5
U2:D
1
3
1
2
1
1
U9:A
4013
Q2
Q1
RESET
4CLK
3D
5SET
6
U5:B
4013
Q
12
Q
13
RESET 10
CLK 11
D9
SET 8
+5V
D2
1N4148
U4
ICL7667
IN2
4
VSS
3
IN1
2
NC
1NC 8
OUT1 7
VDD 6
OUT2 5
1N4936
D1
10uF
C5 IRF740
Q2
R15
820
R10
33K
MC34084
U8:A
1
+3
-2
MC34084
U8:B
7
+5
-6
MC34084
U8:C
8
+
10
-
9
U10:C
8
+10
-9U10:D
14
+12
-13
0.1uF
C9
R4 1M
R6
100K
C8
0.1uF
1000pF,5%
C7
R8
150k
33K
R9
1000pF,5%
C6
L1
162uHy
+5V
R20
820
R17
33K
150K
R19
1000pF,5%
C13
C15
1000pF,5%
C22
0.01uF,630V
1000pF,5%
C12
1000pF,5%
C14
150K
R18
R22
1.82K,1%
R21
33K
R24
820
1N4936
D9
74HC4060
U6
CKI
11
CLR
12
CKO 10
CKO 9
QD 7
QE 5
QF 4
QG 6
QH 14
QI 13
QJ 15
QL 1
QM 2
QN 3
R2
1M
330
R1
C2
22
4.00 MHz
Y1
10uF,16V
C3
+5V
U3
5V
VO 3
G
2
VI
1
470uF,16V
C4
R3
10K
2N2907
Q3
2.67K,1%
R23
1000pF,5%
C16
R27
47.5K,1%
.0022uF,200V,10%
C26
390K
R35
C24
1000pF,200V,5%
R29
82.5K,1%
C21
1000pF,5%
C19
1000pF,5%
10K,1%
R34
C23
1000pF,5%
R32
10K,5%
R26
10K 1%
1000pF,5%
C25
R33
10K,1%
+5V
1N4148
D3
1N4148
D6
R11
22K
100K
R14
R5
3.3K
R7
1.8K
U7
RA2
1
RA3
2
RTCC
3
MCLR
4
VSS
5
RB0
6
RB1
7
RB2
8
RB3
9RB4 10
RB5 11
RB6 12
RB7 13
VDD 14
CKOUT 15
RA0 17
RA1 18
CLKIN 16
330
R16
330
R13
P1
R31
1M,5%
6.8K
R25R30
220,5%
R28
15K
0.1uF
C18
1000pF,5%
C17
C20
10uf,16V
C11
0.1uF
.47uF
C10
D4
1N4148
10K
R12
4013
U9:B
SET 8
D9
CLK
11
RESET 10
Q
13
Q
12
SP1 C1
22
U5:A
4013
Q2
Q1
RESET
4CLK
3
D
5
SET
6
U8:D
MC34084
-
13
+
12
14
LED1
ARED
AGRN
U2:A
1
3
2
U2:C
10
9
8
U1
12V
LM78L12ACZA
VO 3
G
2
VI
1
PIC16F84
+9-15V
out
in
gnd
RS-232
4
11
* Only stuff this part for
use with a 15V supply.
*
1998 Microchip Technology Inc. DS51167B-page 103
microID™ 125
k
Hz Design Guide
4.0 ANTICOLLISION READER BILL OF MATERIALS
Quantity Type Value Reference Designator Part Number
1 PIEZO Buzzer PKM17EPP-4001 BZ1 MURATA PART #
2 Capacitor 22 pF C1, C2 1330PH-ND
12 Capacitor lOOO pF, 5% C6,C7,C12,C13,C14C15,C16,
C17,C19,C21,C23,C25 P4937-ND
1 Capacitor 1000 pF, 200V, 5% C24 (P3497-ND)
1 Capacitor .0022 µF, 200V, 10% C26 P 3S01 -N D
1 Capacitor 0.01µF, 630V c22 P3509-ND
4 Capacitor 0.1 µF C8, C9, C11, C18 P4539-ND
1 Capacitor 0.47 µF C10 P4967-ND
3 Capacitor 10 µF, 16V C3, C5, C20 P6616-ND
1 Capacitor l00 µF, 25V C4 P10269-ND
1 Capacitor 470 µF, 16V C27 P10247-ND
6 Diode 1N4148 D2, D3, D4, D5, D6, D7 1N4148DICT-ND
3 Diode 1N4936 D1, DB, D9 1N4936CT-ND
1 Bicolor LED P392 LED 1 p392-ND
1 Coil Antenna 162 uBy L1 Custom Wound
1 P-Chain MOSFET IRF9520 Q1 IRF9520 FUTURE
1 N-Chain MOSFET IRF740 Q2 IRF740-ND
1 PNP Transistor 2N2907 Q3 PN2907A-ND
1 N-Chain MOSFET 2N7000 Q4 2N7000DICT-ND
1 Resistor 220, 5% R30 5043CX220ROJ
3 Resistor 330, 5% R1, R13, R16 5043CX330ROJ
3 Resistor 820, 5% R15, R20, R24 5043CX830ROJ
Resistor 1.8K, 5% R7 1K8CR-1/4W-B 5%
1 Resistor 1.82K, 1% R22 1K82MF-1/4W-B 5%
1 Resistor 2.67K, 15 R23 2K67MF-1/4W-B 1%
1 Resistor 3.3K, 5% R5 3K3CR-1/4W-B 5%
1 Resistor 6.8K, 5% R25 6K8CR-1/4W-B 5%
3 Resistor 10R,1’ R26, R33, R34 5043ED10KOOF
3 Resistor 10K, 5% R3, R12, R32 10KCR-1/4W-B 5%
1 Resistor 15K, 5% R28 15KCR-1/4W-B 5%
1 Resistor 22K, 5% R11 22KCR-1/4W-B 5%
4 Resistor 33K, 5% R9,R10, R17, R21 33JCR1/4-B 5%
1 Resistor 47.5K, 1% R27 47K5MF-1/4W-B 1%
1 Resistor 82.5K, 1% R29 82.5KMF-1/4W-B 1%
2 Resistor 100K, 5% R6, R14 5043CX100KOJ
3 Resistor 150K, 5% R8, R18, R19 150KCR-1/4W-B 5%
1 Resistor 390K, 5% R35 390KCR-1/4-B, 5%
3 Resistor 1M, 5% R2, R4, R31 1MOCR-1/4W-B 5%
1 QUA D NOR GATE 74HC02 U2 MM74HC02N-ND
1 5V Regulator LM78L05 U3 NJM78L05A-ND
1 MOSFET Driver ICL7667 U4 ICL7667CPA-ND
2 DUAL FLIP-FLOP 4013 U5, U9 CD4013BCN-ND
Note: All resistors are 5% 1/4 watt carbon film resistors unless otherwise noted. DIGI-KEY part numbers follow
some parts where applicable (these part numbers are only intended as a reference).
microID™ 125
k
Hz Design Guide
DS51167B-page 104 1998 Microchip Technology Inc.
1 Binary Counter 74HC4060 U6 MM74HC4060N-ND
1 Microprocessor PIC16F84 U7 PIC16F84-04/P
2 OP-AMP MC3407 U8, U10 FUTURE PART #
1 Crystal 4.00 MHz Y1 X405-ND
Quantity Type Value Reference Designator Part Number
Note: All resistors are 5% 1/4 watt carbon film resistors unless otherwise noted. DIGI-KEY part numbers follow
some parts where applicable (these part numbers are only intended as a reference).
1998 Microchip Technology Inc. DS51167B-page 105
microID™ 125
k
Hz Design Guide
5.0 FSK ANTICOLLISION SOURCE CODE FOR THE PICmicro® MCU
The following source code is for the PIC16C84 microcontroller used in the FSK reader electronics.
; #=#=#=#=#=#=#=# PROJECT Microchip FSK anticollision Reader #=#=#=#=#=#=#=#
; v008.asm
; PIC16F84 running at 4MHz, Ti=1us
; ///////////////////////////////////////////////////////////////////////////
; Revision history
; ///////////////////////////////////////////////////////////////////////////
;
; Ver Date Comment
;
; 0.01 29 Dec 97 Copied from MChip\Reader\FSK
; 0.02 27 Feb 98 Gap during first half of first bit
; 0.05 28 Apr 98 Change from PIC16C84 to PIC16F84
; 0.06 29 Apr 98 Count to 256 instead of to 512
; 0.07 30 Apr 98 Make PORTB.0 low output (previously demodulated data input)
; 0.07a 08 May 98 Make gaps 80us wide
; 0.08 13 Aug 98 TAKE OUT CODE INTENDED FOR LAB USE ONLY
;
; Tbit=50Tcy=400Ti
; Ttag=96Tbit
; Header=h’802A’
;
processor pic16f84
#include “p16f84.inc”
__config b’00000000000001’
; Code Protect on, power-up timer on, WDT off, XT oscillator
#define _CARRY STATUS,0
#define _ZERO STATUS,2
#define _TO STATUS,4
#define _RP0 STATUS,5
#define _PAGE0 PCLATH,3
#define _BUZZ1 PORTA,0
#define _BUZZ2 PORTA,1
#define _RS232TX PORTA,2
#define _RS232RX PORTA,3
#define _SDA PORTA,4
StartPORTA = b’11100’
StartTRISA = b’01000’
BeepPort = PORTA
Beep0 = StartPORTA
Beep1 = StartPORTA | b’00001’
Beep2 = StartPORTA | b’00010’
#define _UNUSED1 PORTB,0
#define _COIL_PWR PORTB,1
#define _LED1 PORTB,2
#define _LED2 PORTB,3
#define _RAW_DATA PORTB,4
#define _UNUSED2 PORTB,5
#define _COLLISION PORTB,6 ; < Goes low when a collision occurs
#define _SCL PORTB,7
StartPORTB = b’10000010’ ; Coil_Off
StartTRISB = b’01010000’
StartOPTION = b’10001111’
; PORTB pullups disabled, TMR0 internal, prescaler off, WDT/256
BO3 = h’0C’ ; Could be doubled-up with DelayReg1
DelayReg1 = h’0D’ ; Could be doubled-up with BO3
BitCtr = h’0E’ ; Could be doubled-up with BeepCtrHi
microID™ 125
k
Hz Design Guide
DS51167B-page 106 1998 Microchip Technology Inc.
TxByte = h’0F’ ; Could be doubled-up with BeepCtrLo
TagsDetected = h’10’
GapCountLo = h’11’
Counter1 = h’12’
Counter2 = h’13’
Flags = h’14’
#define _GotHeader Flags,0
#define _FirstTime Flags,1
Period = h’15’ ; Used to read FSK
GapCountHi = h’16’
Buffer00 = h’18’ ; --- IMMOBILE --- IMMOBILE --- IMMOBILE --- IMMOBILE
Buffer01 = h’19’ ; |
Buffer02 = h’1A’ ; |
Buffer03 = h’1B’ ; |
Buffer04 = h’1C’ ; |
Buffer05 = h’1D’ ; |
Buffer06 = h’1E’ ; |
Buffer07 = h’1F’ ; |
Buffer08 = h’20’ ; |
Buffer09 = h’21’ ; |
Buffer0A = h’22’ ; |
Buffer0B = h’23’ ; |
Buffer0C = h’24’ ; |
Buffer0D = h’25’ ; |
Buffer0E = h’26’ ; |
Buffer0F = h’27’ ; |
Buffer10 = h’28’ ; |
Buffer11 = h’29’ ; |
Buffer12 = h’2A’ ; |
Buffer13 = h’2B’ ; |
Buffer14 = h’2C’ ; |
Buffer15 = h’2D’ ; |
Buffer16 = h’2E’ ; |
Buffer17 = h’2F’ ; |
BeepCtrHi = h’30’ ; Could be doubled-up with BitCtr
BeepCtrLo = h’31’ ; Could be doubled-up with TxByte
SKIP macro
BTFSC PCLATH,7
endm
Coil_On macro
BCF _COIL_PWR
endm
Coil_Off macro
BSF _COIL_PWR
endm
org h’0000’ ; *#*#*#* RESET VECTOR *#*#*#*
CLRF PCLATH
CLRF INTCON
CLRF STATUS
GOTO RESET_A
org h’0004’ ; *#*#*#* INTERRUPT VECTOR *#*#*#*
CLRF PCLATH
CLRF INTCON
CLRF STATUS
GOTO RESET_A
; ***** Subroutines, Page 0
Delay10: ;[0] Delay 10Ti
1998 Microchip Technology Inc. DS51167B-page 107
microID™ 125
k
Hz Design Guide
GOTO Delay08 ; |
Delay08: ;[0] Delay 8Ti
GOTO Delay06 ; |
Delay06: ;[0] Delay 6Ti
NOP ; |
Delay05: ;[0] Delay 5Ti
NOP ; |
Delay04: ;[0] Delay 4Ti
RETLW 0 ; |
;%% CALL RS232CR takes 1052Ti
;%% CALL RS232TxDigit takes 1057Ti
;%% CALL RS232TxW takes 1049Ti
RS232CR: ;[1] Transmit CR on RS232
MOVLW d’13’ ; |
GOTO RS232TxW ; |
RS232TxDigit: ;[1] Transmit LSnybble of W on RS232
ANDLW h’0F’ ; |
MOVWF TxByte ; |
MOVLW h’A’ ; |
SUBWF TxByte,W ; |
MOVLW ‘0’ ; |
BTFSC _CARRY ; |
MOVLW ‘A’-h’A’ ; |
ADDWF TxByte,W ; |
RS232TxW: ;[1] Transmit W on RS232 at 9615 baud
MOVWF TxByte ; | TxByte=W
RS232Tx: ;[1] Transmit TxByte - 104us = 9615.4 baud
BSF _RS232TX ; | Stop bit
MOVLW d’35’ ; | | Delay 106Ti
MOVWF DelayReg1 ; | | |
RS232TxD1: ; | | |
DECFSZ DelayReg1,f ; | | |
GOTO RS232TxD1 ; | | |
BCF _RS232TX ; | Start bit
NOP ; | | Delay 98Ti
MOVLW d’32’ ; | | |
MOVWF DelayReg1 ; | | |
RS232TxD2: ; | | |
DECFSZ DelayReg1,f ; | | |
GOTO RS232TxD2 ; | | |
CLRF BitCtr ; | BitCtr=#8
BSF BitCtr,3 ; | |
RS232TxL1: ; | {% -4Ti
BTFSC TxByte,0 ; | Transmit TxByte.0, RR TxByte
GOTO RS232TxBit1 ; | |
NOP ; | |
RS232TxBit0: ; | |
BCF _RS232TX ; | |
BCF _CARRY ; | |
GOTO RS232TxBitDone ; | |
RS232TxBit1: ; | |
BSF _RS232TX ; | |
BSF _CARRY ; | |
GOTO RS232TxBitDone ; | |
RS232TxBitDone: ; | |
RRF TxByte,f ; | |% 4Ti
MOVLW d’30’ ; | Delay 93Ti
MOVWF DelayReg1 ; | |
GOTO RS232TxD3 ; | |
RS232TxD3: ; | |
DECFSZ DelayReg1,f ; | |
GOTO RS232TxD3 ; | |
DECFSZ BitCtr,f ; | DEC BitCtr
GOTO RS232TxL1 ; | } until (BitCtr==#0)
CALL Delay04 ; | Delay 4Ti
microID™ 125
k
Hz Design Guide
DS51167B-page 108 1998 Microchip Technology Inc.
BSF _RS232TX ; | stop bit
RETLW 0 ; end
DelayTtag: ;[?] Delay Ttag-3Ti=38400-3Ti=38397Ti
BSF _PAGE0
GOTO P1DelayTtag
; ***** End of subroutines, Page 0
RESET_A:
CLRWDT
; Initialise registers
CLRF STATUS ; | Access register page 0
CLRF FSR ; | FSR=#0
MOVLW StartPORTA ; | Initialise PORT and TRIS registers
MOVWF PORTA ; | |
MOVLW StartPORTB ; | |
MOVWF PORTB ; | |
BSF _RP0 ;^| |
MOVLW StartTRISA ;^| |
MOVWF TRISA ;^| |
MOVLW StartTRISB ;^| |
MOVWF TRISB ;^| |
BCF _RP0 ; | Initialise OPTION register
MOVLW StartOPTION ; | |
CLRF TMR0 ; | |
BSF _RP0 ;^| |
MOVWF OPTION_REG ;^| |
BCF _RP0 ; | |
BigLoop1:
CALL Delay08 ; LEDs “reading”
BSF _LED1 ; |
CALL Delay08 ; |
BCF _LED2 ; |
CALL Delay08 ; |
Coil_Off ; Turn coil off
BSF _PAGE0
GOTO ResetDelay
ResetDelayDone:
CLRF TagsDetected ; TagsDetected=#0
CLRF GapCountHi ; GapCount=#0
CLRF GapCountLo ; |
GapLoop: ; {
Coil_Off ; Turn coil off
CALL Delay08 ; LEDs “reading”
BSF _LED1 ; |
CALL Delay08 ; |
BCF _LED2 ; |
CALL Delay10 ; Wait 80us
CALL Delay10 ; |
CALL Delay10 ; |
CALL Delay10 ; |
CALL Delay10 ; |
CALL Delay10 ; |
NOP ; |
Coil_On ; Turn coil on
;% 0 Ti from 1st bit
;(Ttag=38400Ti)
; If it’s the first gap since reset, delay Ttag
BTFSC _FirstTime
1998 Microchip Technology Inc. DS51167B-page 109
microID™ 125
k
Hz Design Guide
CALL DelayTtag
BCF _FirstTime
CLRF DelayReg1 ; Delay 2047Ti
GapD1: ; |
CLRWDT ; |
DECFSZ DelayReg1,f ; |
GOTO GapD1 ; |
GapD2: ; |
CLRWDT ; |
DECFSZ DelayReg1,f ; |
GOTO GapD2 ; |
;% 2050Ti from 1st bit
MOVLW d’8’ ; DelayReg1=#8
MOVWF DelayReg1 ; |
;% 2052Ti from 1st bit
;% 2076-3*DelayReg1 from 1st bit
;% 5*400+76-3*DelayReg1 from 1st bit
;% 76-3*DelayReg1 Ti from 6th bit
; Read tag, with timeouts everywhere
MOVLW d’2’ ; | Counter2=#2
MOVWF Counter2 ; | |
ReadBit_L1: ; | {% 78-3*DelayReg1 Ti from bit
MOVLW d’96’ ; | BitCtr=#96
MOVWF BitCtr ; | |
ReadBit_L2: ; | {% 80-3*DelayReg1 Ti from bit
ReadBit_D1: ; | delay
DECFSZ DelayReg1,f ; | |
GOTO ReadBit_D1 ; | |
; | % 79Ti from bit
CLRF Counter1 ; | Counter1=#0
; | % 80Ti=10Tcy from bit, time to start frequency sample
ReadBit_Hi0: ; | {% 80+(Counter1*8)Ti from bit
INCF Counter1,f ; | ++Counter1
; | % 73+(Counter1*8)Ti from bit
BTFSC Counter1,6 ; | if (timeout)
GOTO GapX ; | { goto GapX } // could be at 1st half of 1st bit!!!
NOP ; | |
BTFSC _RAW_DATA ; | } until (_RAW_DATA==#1)
BTFSS _RAW_DATA ; | |
GOTO ReadBit_Hi0 ; | |
NOP ; | |
ReadBit_Lo0: ; | {% 80+(Counter1*8)Ti from bit
INCF Counter1,f ; | ++Counter1
; | % 73+(Counter1*8)Ti from bit
BTFSC Counter1,6 ; | if (timeout)
GOTO GapX ; | { goto GapX } // could be at 1st half of 1st bit!!!
NOP ; | |
BTFSS _RAW_DATA ; | } until (_RAW_DATA==#0)
BTFSC _RAW_DATA ; | |
GOTO ReadBit_Lo0 ; | |
NOP ; | |
; | % 80+(Counter1*8)Ti from bit
MOVF Counter1,W ; | Period=Counter1
MOVWF Period ; | |
INCF Counter1,f ; | |
CALL Delay05 ; | |
ReadBit_Hi1: ; | {% 80+(Counter1*8)Ti from bit
INCF Counter1,f ; | ++Counter1;
; | % 73+(Counter1*8)Ti from bit
BTFSC Counter1,6 ; | if (timeout)
GOTO GapX ; | { goto GapX } // could be at 1st half of 1st bit!!!
NOP ; | |
BTFSC _RAW_DATA ; | } until (_RAW_DATA==#1)
BTFSS _RAW_DATA ; | |
microID™ 125
k
Hz Design Guide
DS51167B-page 110 1998 Microchip Technology Inc.
GOTO ReadBit_Hi1 ; | |
NOP ; | |
ReadBit_Lo1: ; | {% 80+(Counter1*8)Ti from bit
INCF Counter1,f ; | ++Counter1;
; | % 73+(Counter1*8)Ti from bit
BTFSC Counter1,6 ; | if (timeout)
GOTO GapX ; | { goto GapX } // could be at 1st half of 1st bit!!!
NOP ; | |
BTFSS _RAW_DATA ; | } until (_RAW_DATA==#0)
BTFSC _RAW_DATA ; | |
GOTO ReadBit_Lo1 ; | |
NOP ; | |
ReadBit_Hi2: ; | {% 80+(Counter1*8)Ti from bit
INCF Counter1,f ; | ++Counter1;
; | % 73+(Counter1*8)Ti from bit
BTFSC Counter1,6 ; | if (timeout)
GOTO GapX ; | { goto GapX } // could be at 1st half of 1st bit!!!
NOP ; | |
BTFSC _RAW_DATA ; | } until (_RAW_DATA==#1)
BTFSS _RAW_DATA ; | |
GOTO ReadBit_Hi2 ; | |
NOP ; | |
ReadBit_Lo2: ; | {% 80+(Counter1*8)Ti from bit
INCF Counter1,f ; | ++Counter1;
; | % 73+(Counter1*8)Ti from bit
BTFSC Counter1,6 ; | if (timeout)
GOTO GapX ; | { goto GapX } // could be at 1st half of 1st bit!!!
NOP ; | |
BTFSS _RAW_DATA ; | } until (_RAW_DATA==#0)
BTFSC _RAW_DATA ; | |
GOTO ReadBit_Lo2 ; | |
NOP ; | |
; | % 80+(Counter1*8)Ti from bit
MOVF Period,W ; | Period=Counter1-Period
SUBWF Counter1,W ; | |
MOVWF Period ; | |
; | % 83+(Counter1*8)Ti from bit
COMF Counter1,W ; | W=32-Counter1
ADDLW d’1’ ; | |
ADDLW d’32’ ; | |
; | % 86+(32-W)*8Ti from bit
; | % 86+(Counter1*8)Ti from bit
INCF Counter1,f ; | ++Counter1
INCF Counter1,f ; | ++Counter1
NOP ; | |
; | % 89+(32-W)*8Ti from bit
; | % 73+(Counter1*8)Ti from bit
BTFSS _CARRY ; | if (W<0)
GOTO GapX ; | { goto GapX } // could occur in 1st half of 1st bit!!!
; | % 91+(32-W)*8Ti from bit
MOVWF Counter1 ; | Counter1=W
; | % 92+(32-Counter1)*8 Ti from bit
ReadBit_D2: ; | Delay 4+Counter1*8 Ti
MOVF Counter1,f ; | |
BTFSC _ZERO ; | |
GOTO ReadBit_D2_done ; | |
NOP ; | |
NOP ; | |
DECF Counter1,f ; | |
GOTO ReadBit_D2 ; | |
ReadBit_D2_done: ; | |
; | % 92+32*8-(oldCounter1)*8+4+(oldCounter1)*8 Ti from bit
; | % 352Ti from bit
BTFSS _COLLISION ; | if (collision occurred)
GOTO Gap1 ; | { goto Gap1 } // after 1st half of bit
MOVF Period,W ; | if (Period<#14)
1998 Microchip Technology Inc. DS51167B-page 111
microID™ 125
k
Hz Design Guide
ADDLW low(0-d’14’) ; | |
BTFSS _CARRY ; | |
GOTO Gap0 ; | { goto Gap0 } // after 1st half of bit
ADDLW low(d’14’-d’18’); | if (Period<#18)
BTFSS _CARRY ; | |
GOTO ReadBit_Got0 ; | { goto ReadBit_Got0 }
ADDLW low(d’18’-d’22’); | if (Period>=#22)
BTFSC _CARRY ; | |
GOTO Gap0 ; | { goto Gap0 } // after 1st half of bit
ReadBit_Got1: ; | % 364Ti from bit
BSF _CARRY ; | _CARRY=#1
GOTO ReadBit_GotBit ; | goto ReadBit_GotBit
ReadBit_Got0: ; | % 362Ti from bit
NOP ; | |
NOP ; | |
BCF _CARRY ; | |
GOTO ReadBit_GotBit ; | |
ReadBit_GotBit: ; | % 367Ti from bit
RLF Buffer00,f ; | roll in _CARRY
RLF Buffer01,f ; | |
RLF Buffer02,f ; | |
RLF Buffer03,f ; | |
RLF Buffer04,f ; | |
RLF Buffer05,f ; | |
RLF Buffer06,f ; | |
RLF Buffer07,f ; | |
RLF Buffer08,f ; | |
RLF Buffer09,f ; | |
RLF Buffer0A,f ; | |
RLF Buffer0B,f ; | |
RLF Buffer0C,f ; | |
RLF Buffer0D,f ; | |
RLF Buffer0E,f ; | |
RLF Buffer0F,f ; | |
RLF Buffer10,f ; | |
RLF Buffer11,f ; | |
RLF Buffer12,f ; | |
RLF Buffer13,f ; | |
RLF Buffer14,f ; | |
RLF Buffer15,f ; | |
RLF Buffer16,f ; | |
RLF Buffer17,f ; | |
; | % 391Ti from bit
; | % -9Ti from bit (Tbit=400Ti)
MOVLW d’28’ ; | DelayReg1=#28
MOVWF DelayReg1 ; | |
; | % -7Ti from bit
; | % 77-3*DelayReg1 Ti from bit
DECFSZ BitCtr,f ; | DEC BitCtr
GOTO ReadBit_L2 ; | } until (BitCtr==#0)
; | % -5Ti from bit
MOVLW d’26’ ; | DelayReg=#26
MOVWF DelayReg1 ; | |
; | % -3Ti from bit
; | % 75-3*DelayReg1 Ti from bit
DECFSZ Counter2,f ; | DEC Counter2
GOTO ReadBit_L1 ; | } until (Counter2==#0)
; % -1Ti from first bit
BSF _PAGE0 ; Delay 1568Ti
GOTO BigDelay ; |
BigDelayDone: ; |% 1567Ti from first bit
microID™ 125
k
Hz Design Guide
DS51167B-page 112 1998 Microchip Technology Inc.
CheckTtag: ; if (tag is not 96 bits long) { goto Gap2 }
MOVLW Buffer00 ; | FSR=#Buffer00
MOVWF FSR ; | |
MOVLW h’0C’ ; | Counter1=h’0C’
MOVWF Counter1 ; | |
CheckTTagLoop: ; | {% 1571+(12-Counter1)*15Ti from first bit
BTFSS _COLLISION ; | if (collision occurred)
GOTO Gap1 ; | { goto Gap1 } // never happens during first bit
MOVF INDF,W ; | Counter2=INDF
MOVWF Counter2 ; | |
MOVLW h’0C’ ; | FSR=FSR+h’0C’
ADDWF FSR,f ; | |
MOVF INDF,W ; | if (Couter2!=INDF)
XORWF Counter2,W ; | |
BTFSS _ZERO ; | |
GOTO Gap2 ; | { goto Gap2 } // never happens during first bit
MOVLW low(0-h’0C’+1) ; | FSR=FSR-h’0C’+1
ADDWF FSR,f ; | |
DECFSZ Counter1,f ; | DEC Counter1
GOTO CheckTTagLoop ; | } until (Counter1==#0)
; % 1570+12*15Ti = 1752Ti from first bit
HeadSearch: ; if (no header in Buffer) { goto Gap2 }
MOVLW d’96’ ; | set BitCtr
MOVWF BitCtr ; | |
HeadSearchL1: ; | {% 1752+(96-BitCtr)*31 Ti from first bit
BTFSS _COLLISION ; | if (collision occurred)
GOTO Gap1 ; | { goto Gap1 } // never happens during 1st bit
BSF _GotHeader ; | if (header found) { goto HeadFound }
MOVF Buffer0B,W ; | |
XORLW h’80’ ; | |
BTFSS _ZERO ; | |
BCF _GotHeader ; | |
MOVF Buffer0A,W ; | |
XORLW h’2A’ ; | |
BTFSS _ZERO ; | |
BCF _GotHeader ; | |
BTFSC _GotHeader ; | |
GOTO HeadFound ; | |
RLF Buffer00,f ; | ROL Buffer
RLF Buffer01,f ; | |
RLF Buffer02,f ; | |
RLF Buffer03,f ; | |
RLF Buffer04,f ; | |
RLF Buffer05,f ; | |
RLF Buffer06,f ; | |
RLF Buffer07,f ; | |
RLF Buffer08,f ; | |
RLF Buffer09,f ; | |
RLF Buffer0A,f ; | |
RLF Buffer0B,f ; | |
BCF Buffer00,0 ; | |
BTFSC _CARRY ; | |
BSF Buffer00,0 ; | |
DECFSZ BitCtr,f ; | DEC BitCtr
GOTO HeadSearchL1 ; | } until (BitCtr==#0)
; |% 1751+96*31 Ti = 4727Ti from first bit
GOTO Gap2 ; | goto Gap2 // never happens during first bit
HeadFound: ; % 1766+(96-BitCtr)*29 Ti from first bit
; Delay to fixed time
HeadDelay: ; | {% 1766+(96-BitCtr)*31 Ti from first bit
BTFSS _COLLISION ; | if (collision occurred)
GOTO Gap1 ; | { goto Gap1 } // never happens during 1st bit
CALL Delay08 ; | Delay 26Ti
CALL Delay08 ; | |
CALL Delay06 ; | |
CALL Delay04 ; | |
1998 Microchip Technology Inc. DS51167B-page 113
microID™ 125
k
Hz Design Guide
DECFSZ BitCtr,f ; | DEC BitCtr
GOTO HeadDelay ; | } until (BitCtr==#0)
; % 1765+96*31 = 4741Ti from first bit
BTFSS _COLLISION ; if (collision occurred)
GOTO Gap1 ; { goto Gap1 } // never happens during 1st bit
; % 4743Ti from first bit
BSF _LED2 ; LEDs “Found tag”
CALL Delay08 ; |
BCF _LED1 ; |
; % 4753Ti from first bit
SWAPF Buffer0B,W ; Transmit tag ID
CALL RS232TxDigit ; |%% CALL RS232TxDigit takes 1057Ti
MOVF Buffer0B,W ; |
CALL RS232TxDigit ; |%% CALL RS232TxDigit takes 1057Ti
SWAPF Buffer0A,W ; |
CALL RS232TxDigit ; |%% CALL RS232TxDigit takes 1057Ti
MOVF Buffer0A,W ; |
CALL RS232TxDigit ; |%% CALL RS232TxDigit takes 1057Ti
SWAPF Buffer09,W ; |
CALL RS232TxDigit ; |%% CALL RS232TxDigit takes 1057Ti
MOVF Buffer09,W ; |
CALL RS232TxDigit ; |%% CALL RS232TxDigit takes 1057Ti
SWAPF Buffer08,W ; |
CALL RS232TxDigit ; |%% CALL RS232TxDigit takes 1057Ti
MOVF Buffer08,W ; |
CALL RS232TxDigit ; |%% CALL RS232TxDigit takes 1057Ti
SWAPF Buffer07,W ; |
CALL RS232TxDigit ; |%% CALL RS232TxDigit takes 1057Ti
MOVF Buffer07,W ; |
CALL RS232TxDigit ; |%% CALL RS232TxDigit takes 1057Ti
SWAPF Buffer06,W ; |
CALL RS232TxDigit ; |%% CALL RS232TxDigit takes 1057Ti
MOVF Buffer06,W ; |
CALL RS232TxDigit ; |%% CALL RS232TxDigit takes 1057Ti
SWAPF Buffer05,W ; |
CALL RS232TxDigit ; |%% CALL RS232TxDigit takes 1057Ti
MOVF Buffer05,W ; |
CALL RS232TxDigit ; |%% CALL RS232TxDigit takes 1057Ti
SWAPF Buffer04,W ; |
CALL RS232TxDigit ; |%% CALL RS232TxDigit takes 1057Ti
MOVF Buffer04,W ; |
CALL RS232TxDigit ; |%% CALL RS232TxDigit takes 1057Ti
SWAPF Buffer03,W ; |
CALL RS232TxDigit ; |%% CALL RS232TxDigit takes 1057Ti
MOVF Buffer03,W ; |
CALL RS232TxDigit ; |%% CALL RS232TxDigit takes 1057Ti
SWAPF Buffer02,W ; |
CALL RS232TxDigit ; |%% CALL RS232TxDigit takes 1057Ti
MOVF Buffer02,W ; |
CALL RS232TxDigit ; |%% CALL RS232TxDigit takes 1057Ti
SWAPF Buffer01,W ; |
CALL RS232TxDigit ; |%% CALL RS232TxDigit takes 1057Ti
MOVF Buffer01,W ; |
CALL RS232TxDigit ; |%% CALL RS232TxDigit takes 1057Ti
SWAPF Buffer00,W ; |
CALL RS232TxDigit ; |%% CALL RS232TxDigit takes 1057Ti
MOVF Buffer00,W ; |
CALL RS232TxDigit ; |%% CALL RS232TxDigit takes 1057Ti
;% 30145Ti from first bit
CALL RS232CR ;%% CALL RS232CR takes 1052Ti
;% 31197Ti from first bit
microID™ 125
k
Hz Design Guide
DS51167B-page 114 1998 Microchip Technology Inc.
MOVLW d’255’ ; Delay 7396Ti
MOVWF DelayReg1 ; |
WaitingL1: ; |
CLRWDT ; |
CALL Delay10 ; |
CALL Delay10 ; |
CALL Delay05 ; |
DECFSZ DelayReg1,f ; |
GOTO WaitingL1 ; |
;% 38593Ti from first bit
;% 38400+193 = 193Ti from first bit, -7Ti from gap
INCFSZ GapCountLo,f ; INC GapCount
SKIP ; |
INCF GapCountHi,f ; |
BTFSC GapCountHi,0 ; } until (GapCount>#257)
BTFSS GapCountLo,1 ; |
GOTO GapLoop ; |
GOTO BigLoop1
Gap1: ; !!!!! goto here after collision
; % -4Ti from gap
CLRF GapCountHi
CLRF GapCountLo
GOTO GapLoop
GapX: ;% 76+(Counter1*8)Ti from bit
GapXDelay: ; Delay 3+(128-Counter1)*8Ti
BTFSC Counter1,7 ; |
GOTO GapXDelayDone ; |
INCF Counter1,f ; |
NOP ; |
GOTO GapXDelayJ1 ; |
GapXDelayJ1: ; |
GOTO GapXDelay ; |
GapXDelayDone: ; |
;% 76+(oldCounter1)*8+3+128*8-(oldCounter1)*8Ti from bit
;% 1103Ti from bit = (400*2)+303Ti from bit
;// Not in first half of bit
Gap0: ; !!!!! goto here for gap which does NOT occur in first half of first bit
; % -7Ti from gap
INCFSZ GapCountLo,f ; INC GapCount
SKIP ; |
INCF GapCountHi,f ; |
BTFSC GapCountHi,0 ; } until (GapCount>#257)
BTFSS GapCountLo,1 ; |
GOTO GapLoop ; |
GOTO BigLoop1
Gap2: ; !!!!! goto here for valid FSK but invalid code
INCFSZ GapCountLo,f ; INC GapCount
SKIP ; |
INCF GapCountHi,f ; |
BTFSC GapCountHi,0 ; } until (GapCount>#257)
BTFSS GapCountLo,1 ; |
GOTO GapLoop ; |
GOTO BigLoop1
org h’0200’
P1Delay20:
GOTO P1Delay18
P1Delay18:
NOP
1998 Microchip Technology Inc. DS51167B-page 115
microID™ 125
k
Hz Design Guide
P1Delay17:
NOP
P1Delay16:
GOTO P1Delay14
P1Delay14:
NOP
P1Delay13:
NOP
P1Delay12:
GOTO P1Delay10
P1Delay10:
GOTO P1Delay08
P1Delay08:
GOTO P1Delay06
P1Delay06:
GOTO P1Delay04
P1Delay04:
RETLW 0
BigDelay:
;!!!!! delay (1568-6)Ti = 1562Ti
MOVLW d’15’ ; Delay 1501Ti
MOVWF DelayReg1 ; |
BigDelayL1: ; |
CALL P1Delay20 ; |
CALL P1Delay20 ; |
CALL P1Delay20 ; |
CALL P1Delay20 ; |
CALL P1Delay17 ; |
DECFSZ DelayReg1,f ; |
GOTO BigDelayL1 ; |
CALL P1Delay20 ; Delay 61Ti
CALL P1Delay20 ; |
CALL P1Delay20 ; |
NOP ; |
BCF _PAGE0
GOTO BigDelayDone
P1DelayTtag: ; Delay 38393Ti
CLRF DelayReg1 ; | Delay 38144Ti
P1DelayTtagL1: ; | |
CALL P1Delay20 ; | |
CALL P1Delay20 ; | |
CALL P1Delay20 ; | |
CALL P1Delay20 ; | |
CALL P1Delay20 ; | |
CALL P1Delay20 ; | |
CALL P1Delay20 ; | |
CALL P1Delay06 ; | |
DECFSZ DelayReg1,f ; | |
GOTO P1DelayTtagL1 ; | |
MOVLW d’19’ ; | Delay 248Ti
MOVLW DelayReg1 ; | |
P1DelayTtagL2: ; | |
CALL P1Delay10 ; | |
DECFSZ DelayReg1,f ; | |
GOTO P1DelayTtagL2 ; | |
NOP ; | Delay 1Ti
BCF _PAGE0
RETLW 0
ResetDelay:
CALL RS232CR ; Transmit CR regularly
microID™ 125
k
Hz Design Guide
DS51167B-page 116 1998 Microchip Technology Inc.
MOVLW d’4’ ; Beep at 3597Hz for 1024 cycles
MOVWF BeepCtrHi ; |
MOVLW d’0’ ; |
MOVWF BeepCtrLo ; |% 27277Ti from first bit
BeepLoopJ1: ; |
GOTO BeepLoopJ2 ; |
BeepLoopJ2: ; |
MOVLW Beep1 ; |
MOVWF BeepPort ; |
MOVLW d’34’ ; | Delay 137Ti
MOVWF DelayReg1 ; | |
BeepD1: ; | |
CLRWDT ; | |
DECFSZ DelayReg1,f ; | |
GOTO BeepD1 ; | |
MOVLW Beep2 ; |
MOVWF BeepPort ; |
MOVLW d’32’ ; | Delay 132Ti
MOVWF DelayReg1 ; | |
NOP ; | |
GOTO BeepD2 ; | |
BeepD2: ; | |
CLRWDT ; | |
DECFSZ DelayReg1,f ; | |
GOTO BeepD2 ; | |
DECFSZ BeepCtrLo,f ; |
GOTO BeepLoopJ1 ; |
DECFSZ BeepCtrHi,f ; |
GOTO BeepLoopJ2 ; |
NOP ; |
MOVLW Beep0 ; |
MOVWF BeepPort ; |
MOVLW d’20’ ; Wait ~10ms (reset gap)
MOVWF Counter1 ; |
ResetGapL1: ; |
MOVLW d’124’ ; | Wait ~500us
MOVWF DelayReg1 ; | |
ResetGapL2: ; | |
CLRWDT ; | |
DECFSZ DelayReg1,f ; | |
GOTO ResetGapL2 ; | |
DECFSZ Counter1,f ; |
GOTO ResetGapL1 ; |
BSF _FirstTime
Coil_On ; Turn coil on
MOVLW d’6’ ; Wait ~6ms
MOVWF Counter1 ; |
ResetDelayL1: ; |
MOVLW d’250’ ; |
MOVWF DelayReg1 ; |
ResetDelayL2: ; |
CLRWDT ; |
DECFSZ DelayReg1,f ; |
GOTO ResetDelayL2 ; |
DECFSZ Counter1,f ; |
GOTO ResetDelayL1 ; |
BCF _PAGE0
GOTO ResetDelayDone
end
1998 Microchip Technology Inc. DS51139A-page 117
MmicroID™ 125 kHz DESIGN GUIDE
1.0 INTRODUCTION
The following is a description of how to program
Microchip’s MCRF2XX family of RFID products. A
contactless programmer (PG103001), user interface
software (RFLAB™), and a host computer are needed
to prog ram the MCRF2XX de vices. The de vice can also
be programmed in a standard terminal mode (i.e.,
c:\windows\terminal.exe) rather than the RFLAB. See
Figure 5-1 for the programming sequence.
The microID programmer requires an external power
supply (+9 VDC, >750 mA). The RFLAB software runs
under Microsoft® (MS) Wi ndows® 95 environment only.
The programmer communicates with a host computer
via an RS-232 serial interface at 9600 baud, 8 data bits,
1 stop bit, and no parity.
Since the MCRF2XX is a One-Time-Programmable
(OTP) device, only a blank (unlocked) device can be
programmed by the programmer. Therefore, the pro-
grammer first checks the status of the memory in the
device before initiating programming. A blank device
contains an array of all ‘1’s.
The de vice can be programmed with 16 byt es (128 bits)
or 12 bytes (96 bits) of data length. Once the
MCRF2XX enters its programming mod e , it se ts a lock
bit at the same time. If the programming is interrupted
for an y reason d uring the prog rammi ng period, the pro-
gramming will be stopped, and the device may be left
partially programmed. The device will still be locked
e ven thoug h it has not been programmed completely. In
this case, the programmer will retur n a fail code to the
host computer.
Any device that has been programmed, either fully or
partially, will remain in a locked status; therefore, it
cannot to be reprogrammed. If programming has been
successfully completed, the programmer will return a
verification code to the host computer.
In order to program the MCRF2XX device, it is
necessary to provide a proper programming signal
level to the device. The device requires specific peak-
to-peak voltages for programming. Since the voltage
induced in the tag coil varies depending on the coil
parame ters, th e output si gnal level of t he progra mmer
must be calibrated to provide a proper programming
signal level at the tag coil. A detailed calibration
procedure is described in Section 3.0.
FIGURE 1-1: RFLAB SOFTWARE RUNNING UNDER MS WINDOWS 95
Using the microID™ Programmer
RFLAB is a trademark of Microchip Technology Inc.
microID™ 125
k
Hz Design Guide
DS51139A-page 118 1998 Microchip Technology Inc.
2.0 PROGRAMMING SIGNAL
WAVEFORM
Figure 2-1 shows the waveform of the programming
signal. Once the programmer sends a power-up and
gap signal to the device, the device transmits back a
verification bitstream in FSK. The verification signal
represents the contents of the memory in the device.
The blank device has all ‘1’s in its memory. A bit ‘1’ in
FSK is represented by a low signal level f or five cycles
and a high signal level for an additional five cycles
(Figure 2-1).
The device w i ll respond with a n onm od ulated (no da ta)
signal if the device has not recognized the power-up
signal . In this cas e, the p ow er-up sign al le v el should be
calibr ated to pr ovide a proper signa l le vel to the de vice .
The calibration procedure is explained in Section 3.0.
After the device is verified as blank, the programmer
sends a programming signal to the device. The pro-
gramming da ta is represented by an amplitude modu-
lation signal. Therefore, bit ‘1’ and ‘0’ are represented
by a low-power (level) signal and a high power (level)
signal, respectively, as shown in Figure 2-1. Each data
bit is re presented b y 128 cycl es of the carrier sign al. An
MCRF200 configured for 128 bits uses all bits in the
transfer; an MCRF200 configured for 96 bits ignores
bits 33 through 64, al though they are present in the pro-
gramming sequence. Therefore, for a 125 kHz carrier
signal, it takes 1.024 ms for one data bit (128 cycles x
8 µs/cycles) and 131.072 ms for 128 data bits
(128 cycles/bit x 8 µs/cycle x 128 bits).
A guard-band of ∆t = 10 cy cl es (8 0 µs) should be kept
at each end of a high-power (0) bit as shown in
Figure 2-1. This is to prevent accidental programming
or disturbing of adjacent bits in the array.
The mem ory arr ay is loc ked at the start of the prog ram-
ming cycle. Therefore, when the de vice leaves the pro-
gramming field, it locks the memory permanently,
regardless of the programming status. The device
should not be interrupted during the programming
cycle.
The device transmits the programmed (data contents)
circuits back to the programmer for verification. If the
v erifi ca tio n bi tst r eam is cor r ect , the pr og r am m er s end s
a v eri fie d si gna l (‘ v’) to the hos t c om put er; otherwis e , it
sends an error message (‘n’, see Figure 5-1).
The programming signal level must be within a limit of
the programming voltage window for successful pro-
gramming. The calibration of the signal level is
ex plained in Section 3.0.
2.1 Power-up, Gap, and Verification
Signals
The programming signal star ts with a power-up signal
for 80 ~ 180 µS, followed by a gap signal (0 volt) for
50 ~ 100 µS. The pu r pos e of th ese signa ls is to check
whether the device is blank and establish a program-
ming mo de in the device. Onc e the device reco gnizes
the pow er-up signal, it transmits bac k the contents of its
memory. If the device transmits back with the blank
bitstream (FSK with all ‘1’s), it is ready to be pro-
grammed. If the device is not blank, the programmer
informs the host computer that it is nonprogrammable.
If the power-up signal level is out of the programming
voltage range, the device will transmit back a
non-modulated signal (no data). The nonmodulated
signal has no variation in the amplitude (constant
voltage s igna l). A vari able res ist or, R5 in t he micr oID
programmer, should be adjusted to provide a proper
power-up signal level. A typical signal level is about
22 ± 3 VPP across the tag coil. This calibration
procedure is described in Section 3.0.
2.2 Programming Sequence
Once the device has been verified blank for program-
ming, th e progr ammer sends a progr amming se quence
to the device. The programming data entered in the
RFLAB software is sent to the device via the
programmer. The programming signal waveforms are
shown in Figure 2-1. One bit of data is represented by
128 cycles of the carrier signal. It takes 131.072 ms to
complete one programming cycle for the total of 128
data bits . An MCR F200 c onfigu red for 128 bits uses all
bits in the transfer; an MCRF200 configured for 96 bits
ignores bits 33 through 64, althou gh they a re present in
the programming sequence. After the programming
sequence, the device transmits back a verification
bitstream. The programmer reports to the host
computer the status of the programming.
The data is progr ammed only if the pr ogrammi ng signal
level is within the limit in the programming voltage
requirement of the device. It takes several
prog ram ming/ v erify cy cles to c omple tely pr ogr am e ach
bit of the MCRF2 00. The mic roID progr ammer us es ten
(10) blind program/verify cycles before checking the
final verify sequence for correct programming. Faster
programmers can be designed by checking each
program/verify cycle; after approximately 3 ~ 5 cycles,
the device will verify correctly. Once a correct verify
sequence is received, one additional program cycle
should be run to ensure proper programming margin.
1998 Microchip Technology Inc. DS51139A-page 119
microID™ 125
k
Hz Design Guide
FIGURE 2-1: CONTACTLESS PROGRAMMING WAVEFORM
POWER UP GAP
~ 50 - 100 µs Not Modulating
Modulating
High
Power
33 ± 1VPP
Bit 1 Bit 2
128 bits x 128 cycles/bit x 8 µs/cycle = 131.1 ms
22 ± 3 VPP
Contactless Programming Protocol
f = 125 kHz
t = 8 µs
Bit 3…
PROGRAM
1 bit = 128 cycles x 8 µs/cycle = 1.024 ms
80 - 180 µs
VERIFY
FSK Signal
(R5)
128 bits
∆t = Guard Band
0V
22 ± 3 VPP
(R5)
Low
Power
Signal Signal ∆t
(R7)
22 ± 3 VPP
Note: Low-power signal leaves bit = 1
High-power signal programs bit = 0
∆t
Default programming protocol = FSK, Fc/8/10, 128 bits
For 96-bit programming, bits 33 – 64 are ‘don’t care’, but all
128-bit cycles must be in the sequence.
microID™ 125
k
Hz Design Guide
DS51139A-page 120 1998 Microchip Technology Inc.
3.0 CALIBRATION OF
PROGRAMMING VOLTAGE
If you are using your own tag coil (with resonant
capacitor) with the MCRF200 or MCRF250, you may
need to calibrate the programmer for your circuit.
Follow this procedure, if you are unable to program your
tag.
a) Open the programmer, and turn R5 and R6 full
counter-clockwise. Remove the four screws at
the back of the programmer.
b) Set up the programmer and calibration tag as
shown in Figure 3-1.
Set Up:
• Connect the +9 VDC power s upply to the
programmer.
• Conne ct the RS-232 cab le from the e xternal serial
port in the programmer box to a COM port in the
host.
• Open up the RFLAB software on the host
computer.
• Place the calibration tag in the center of the tag
area on the programmer. A calibration tag is any
tag usi ng MCRF 200 or MCRF250 silico n and y our
own coil and capacitor.
c) Run the programming software (RFLAB).
Power-up Signal Level:
d) Click the Blank Check button in the RFLAB
software.
If the device is blank, a green bar appears in the
window with a message indicating that it is blank.
If the device is not blank or the power-up signal is
out of ra nge, a red bar appea rs i n th e w in do w w i th
an error message indicating that it is not blank.
The variable resistor (R5) in the programmer
should be adjusted to provide a proper “low-power”
v oltage le vel to the tag coil. A typica l signa l le v el is
about 2 2 ± 3 VPP a t the tag coil , but it can vary out-
side of this range.
R5: Turn clockwise in 1/16-inch increments
Repeat step (d) while adjusting R5. Once the device
has been verified as a blank, turn it clockwise one more
increment. Then move to the next step.
Programming Signal Level:
e) Click on the buttons in RFLAB for the
appropriate d ata t yp e an d pro toc ol for your tag.
f) Enter the programming data in the text box.
g) Click the Program button. This will send the
prog ram ming data to the device . A typ ical signa l
level for programming is 33± 1 VPP at the tag
coil, but can vary outside of this range.
h) After the device has been programmed, it
transmits back the programmed data for verifi-
cation.
i) If the data has been programmed correctly, a
green bar will appear for a few seconds with a
message indicating
Programming successful
.
If the programming has been unsuccessful due to
insufficient programming signal levels, a message
indicating
Programming unsuccessful
will appear
in the RFLAB. See Figure 1-1. In this case, R7
(“High Power”) must be adjusted to provide a
proper programming signal level to the tag coil.
Turn R7 clockwise in 1/16 -inch increments , repeat-
ing steps (f) through (h) until programming is suc-
cessful. Then turn R7 clockwise one more
increment.
j) After programming is completed successfully,
keep these R5 and R7 settings for future pro-
gr amming of y our tags. O nce this calibr ation has
been done, remove the calibration tag from the
programmer and reinstall the four screws.
FIGURE 3-1: MCRF2XX microID
PROGRAMMER AND
CALIBRATION TAG COIL
ARRANGEMENT FOR
PROGRAMMING SIGNAL
LEVEL MEASUREMENT
Note: The MCRF200 or MCRF250 lock may be
locked even if the programming cycle was
unsuccessful; therefore, a new MCRF200
sample may be required for each pass
through steps (f) through (h).
Place your coil in
the center of the red
outlined area.
1998 Microchip Technology Inc. DS51139A-page 121
microID™ 125
k
Hz Design Guide
4.0 PROGRAMMING PROCEDURE
a) Set up the prog rammer and o pen up the RFLAB
software on the host computer.
Set Up:
• Connect the +9 VDC power supply to the
programmer.
• Connect from the external serial port in the
programmer box to a COM port in the host com-
puter using the R S-232 cable.
b) Place the RFID device at the center of the
programmer.
c) Cl ick Blank Check bu tton if you want to check
whether the de vice is blank. This b utton can also
be used to verify that the device is assembled
properly.
d) Enter the programming data in the RFLAB and
select appropriate data type.
e) If several devices are going to be programmed
sequentially by any number, click the Auto
Increment button and specify the increment
number.
f) Click the Program button. This will send the
data to the device.
g) If the data has been programmed correctly,
there wil l be a green bar wi th a message indic at-
ing
Programming successful
.
If the programming has been unsuccessful due to
out-of-range in the programming signal level, a
message and red bar will show up indicating
Programming
unsuccessful.
In this case, the
programming signal voltage may need to be
calibrated for your tag. See the calibration proce-
dure fo r t h e p r ogram mi ng si g na l level in the pr evi-
ous se cti on.
h) Repeat step (a) through (g) for other tags.
4.1 Error Conditions
If t he hos t co mpu ter does not send program ming dat a
to the programmer for more than 3 seconds, the
programmer will timeout and reset. If the programmer
does n ot res pond to the host c omput er, there wi ll be an
error message indicating
Programmer time out
. If
invalid programming data is sent to the programmer
during the loading of the program buffer, the
programmer will return a message indicating
Invalid.
Note: The device can’t be programmed unless it
is blank.
microID™ 125
k
Hz Design Guide
DS51139A-page 122 1998 Microchip Technology Inc.
FIGURE 4-1: PROGRAMMING FLOWCHART USING RFLAB
Click “Programmer” Menu Button in RFLAB.
Click “COM Port” Menu Button
Select a COM Port Number
Error Message:
“Programmer Time-out”
No
Click “Blank Check” Button in RFLAB
Signal Level (R5) or try a new tag.
Message with a Green Bar:
“Blank/Programmable”
Yes
Prog
Type in Programming
Message with a Green Bar:
“Programming Successful”
Error Message with a Red Bar:
“Programming Unsuccessful”
Adjust Programming Signal Lev el
Start
Yes
Yes
Check Cable Connection and COM Port
No
Adjust the Programming P ower-up
No
(R5 and R7)
Data in RFLAB
Programmer
power-up and
connection ok?
Blank
and power-up
signal level ok?
Successful?
Stop
Place a blank tag on programmer
Error message with a
“Devi ce not Blank”
or
“Device not present”
Send Program Data:
Click “Program” Button
Message with a Green Bar:
“Blank/Programmable”
Start
(Due to not blank
or incorrect
power-up
signal level)
1998 Microchip Technology Inc. DS51139A-page 123
microID™ 125
k
Hz Design Guide
5.0 PROGRAMMING IN A
STANDARD TERMINAL MODE
In special cases, the device can also be programmed in
a standard terminal mode by executing the
terminal.exe program (c:\windows\terminal.exe) or
by any c ustomer pro duction s oftware . The progra mmer
setup, signal w aveforms, and ca lib rati on proc edure a re
the same as progra mming with the RFLAB.
The following is a de scriptio n of ho w to int erfac e a host
computer to Microchip’s contactless programmer
without the use of RFLAB software. The programmer
will check for a blank, unlocked MCRF2XX tag before
initiating programming. Once programming has been
completed, the programmer will return a pass or fail
code. The programmer communicates at 9600 baud, 8
data bits, 1 stop bit, and no parity.
Figure 5-1 shows the programming flow and
communication handshakes between host and pro-
grammer.
5.1 Programmer Wake-up
Sending an ASCII ‘W’ (57h) to the programmer on the
RS-232 interface will tell the programmer to wake up
and be prepared to receive commands. The
programmer will reply with ASCII ‘R’ (52h) when it is
ready.
5.2 Blank Check
Sending an ASCII ‘T’ (54h) will signal the programmer
to read the part about being con tactlessly program med
and check to see if it is blank (all 1’s) and unlocked. If
the part is blank and unlocked, the programmer will
reply with an ASCII ‘Y’ (59h) to signify programming
should contin ue. I f the part is not blank or not unl ock ed,
the programmer will reply with an ASCII ‘N’ (4Eh) to
indicate an error. It is always necessary to perform a
blank check before programming MCRF2XX devices.
5.2.1 SENDING DATA TO THE PROGRAMMER
If the programmer responds with an ASCII ‘Y’,
indicating that the part is blank, the PC can begin
passing the 16 bytes of required data to the
programmer data buffer. AnMCRF200 configured for
128 bi t s us es al l 1 6 byt es of da ta i n t h e t rans fe r; w h en
programming a 96-bit device, however, bits 33 through
64 are ‘don’t care ’ and are ignored by the MCRF200.
The data should be passed in ASCII equivalent hex
by tes and the prog rammer wil l ackno wledge the recei pt
of each byte by echoing back what it has received. For
examp le, to program 05 hex data into the first by te , the
PC would send ASCII ‘0’ (30h), the programmer would
echo ‘ 0’ bac k. Ne xt , the p rogr amm er wou ld se nd ASCII
‘5’ ( 35h ), an d th e progr amme r wil l ec ho ba ck ‘5’. All o f
the data must be sent in UPPERCASE ASCII
equivalent only. See Figure 5-1 for a typical
programming sequence.
5.3 Program and Verify the Device
After 16 bytes of data have been received by the
programmer, it is ready to begin programming the data
buffer into the MCRF2XX. Sending an ASCII ‘V’ (56h)
will tell the programmer to program the 16 bytes it has
received and verify that the device has programmed
properly. When the device programs properly, the pro-
grammer replies with ASCII ‘y’ (79h). If the program-
ming was not successful, the programmer replies with
ASCII ‘n’ (6Eh). A successful programming operation
should take about 3 to 4 seconds per device.
5.4 Error Conditions
If the PC does not send a byte to the programmer for
more tha n 3 se con ds, the progr am mer w il l t imeou t an d
reset. The entire programming sequence will need to
be repeated, beginning with the programmer wake -up
byte ASCII ‘W’.
If invalid bytes are sent to the programmer during the
loading of the program buffer, the programmer will
return an ASCII ‘I’ (49h). In this case, the entire
programming sequence must be repeated, beginning
with the programmer wake-up by te ASCII ‘W’.
microID™ 125
k
Hz Design Guide
DS51139A-page 124 1998 Microchip Technology Inc.
FIGURE 5-1: TYPICAL SEQUENCE
The following is the programming sequence necessar y to
PC Send
‘W’ to the
programmer
Programmer
replies with
‘R’ to the PC
and verify the de vi ce .
the programmer, and instruct the programmer to program
wake up the programmer, check if a MCRF2XX part is
blank, unlocked and ready to be program me d, send
F1E2D3C4B5A6978888796A 5B4C3D2E 1F ASCII data to
STEP1
STEP2 PC Send
‘T’ to the
programmer
Programmer
replies with ‘Y’
if the device
is OK and ‘N’ if
there is an error
STEP3
PC Send
‘F’ to prog. Programmer replies
with ‘F’
WAKE UP
VERIFY BLANK
PASS 16 BYTES
OF DATA
PC Send
‘1’ to prog. Programmer replies
with ‘1’
PC Send
‘E’ to prog. Programmer replies
with ‘E’
PC Send
‘2’ to prog. Programmer replies
with ‘2’
PC Send
‘2’ to prog. Progr ammer replies
with ‘2’
PC Send
‘E’ to prog. Programmer replies
with ‘E’
PC Send
‘1’ to prog. Progr ammer replies
with ‘1’
PC Send
‘F’ to prog. Programmer replies
with ‘F’
F
1
E
2
2
E
1
F
Byte 1
Byte 2
Byte 15
Byte 16
STEP4
PROGRAM/VERIFY
PC Send ‘V’ to the
programmer to initiate
a program/verify sequence
Programmer
replies with ‘y’
if the device
programs OK and
‘n’ if there is an
error
Note: See the signal waveforms and calibration procedure in
Sections 2.0 and 3.0.
(ID internal program/verify)
1998 Microchip Technology Inc. DS51139A-page 125
microID™ 125
k
Hz Design Guide
TABLE 5-1 ASCII CHARACTER SET
Most Significant Characters
Hex 01234567
Least Significant Characters
0 NUL DLE Space 0 @ P ‘ p
1 SOH DC1 ! 1 A Q a q
2 STX DC2 " 2 B R b r
3 ETX DC3 # 3 C S c s
4 EOT DC4 $ 4 D T d t
5 ENQ NAK % 5 E U e u
6 ACK SYN & 6 F V f v
7BellETB’ 7 G W g w
8BSCAN( 8 H X h x
9HTEM) 9 I Y i y
ALFSUB* : J Z j z
B VT ESC + ; K [ k {
CFFFS , < L \ l |
DCRGS- = M ] m }
ESORS . > N ^ n ~
FSIUS/ ?O_ oDEL
microID™ 125
k
Hz Design Guide
DS51139A-page 126 1998 Microchip Technology Inc.
6.0 microID™ PROGRAMMER SCHEMATIC
1998 Microchip Technology Inc. DS51139A-page 127
microID™ 125
k
Hz Design Guide
7.0 microID™ PROGRAMMER BILL OF MATERIALS
Item # Qty Part # Reference
Designator Part Description Manufacturer Vendor Vendor Part #
1 1 ICA-328-S-ST U4 SOCKET, 28
PIN,.300,
MACHINED
COLLET
SAMTEC
2 1 -S PARE- SP1, LED1, R1,
R2 -SPARE-
LOCATION DO NO T
INSTALL
3 1 PCC 220CNCT-ND C7 CAP SMT, 22 pF
NPO 0805 PANASONIC
4 2 0805N471J101NT C8, C9 CAP SMT, 470 pF
5% 100V 0805 MALLORY
5 1 CD15FC561J O3 C18 CAP, 560 pF, MICA,
DIPPED, 300V,
AX (0.234LS)
CORNELL
DUBILIER MOUSER 5982-15-
300V560
6 1 ECU-V1H102JCX C11 CAP SMT, 1000 pF
50V NPO CER,
0805
PANASONIC
7 1 CD19FD472JO3 C2 CAP, 4700 pF, MICA,
DIPPED, 500V, AX
(0.344LS)
CORNELL
DUBILIER MOUSER 5982-19-
500V4700
8 9 250R18Z104MV4
E-6 C1, C3-C6, C12,
C15-C17 CAP SMT, 0.1 µF
20% 50V 0805 JOHANSON NEWARK 50F3674
9 1 ECS -H1E D106R C13 CAP SMT, 10 µF,
TANT ELE C, 25V,
7343
PANASONIC DIGIKEY PCT5106CT-
ND
10 1 ECE-V0JA101SP C14 CAP SMT, 100 µF,
TANT ELE C, 6.3V,
(VS-D)
PANASONIC DIGIKEY PCE3058CT-
ND
11 1 LL4148 D1 DIODE SMT, 5uA,
100V, 500 mW,
FAST SWIT CHI NG ,
DL-35
DIODES INC DIGIKEY LL4148DITR-
ND
12 1 DL4002 D2 DIODE SMT,
RECTIFIER,
1N4002, 1A, 100V,
DL-41
DIODES INC. DIGIKEY DL4002DITR-
ND
13 1 3345P-1-101 R7 RES, POT, 100 OHM
1/2 RD WW ST SL BOURNS DIGIKEY 3345P-101-ND
14 1 3345P-1-501 R5 RES, POT, 500 OHM
1/2 RD WW ST SL BOURNS DIGIKEY 3345P-501-ND
15 1 ERJ-6GEYJ100 R6 RE S SM T, 10 OHM
1/10W
5% TYPE 0805
PANASONIC P10ACT-ND
16 1 ERJ-6GEYJ470V R4 RES SM T, 47 OHM
1/10W
5% TYPE 0805
PANASONIC DIGIKEY P470ATR-ND
17 1 ERJ-6GEYJ471V R3 RES SMT, 470 OHM
1/10W
5% TYPE 0805
PANASONIC P470ATR-ND
18 1 ERJ-6GEYJ222V R13 RES SMT, 2.2K
OHM 1/10W 5%
TYPE 0805
PANASONIC P2.2KATR-ND
19 1 ERJ-6GEYJ103V R8 RES SMT, 10K 1/8W
5% TYPE 0805 PANASONIC DIGIKEY P10KATR-ND
microID™ 125
k
Hz Design Guide
DS51139A-page 128 1998 Microchip Technology Inc.
20 1 ERJ-6GEYJ473V R11 RES SMT, 47K OHM
1/10W
5% TYPE 0805
PANASONIC DIGIKEY P473ATR-ND
21 2 ERJ-6GEYJ104V R12, R14 RES SMT, 100K
OHM 1/10W 5%
TYPE 0805
PANASONIC DIGIKEY P100KATR-ND
22 1 ERJ-6GEYJ154V R10 RES SMT, 150K
OHM 1/8W 5% 0805 PANASONIC DIGIKEY P150KATR-ND
23 1 ERJ-6GEYJ474V R9 RES SM T, 470K
OHM 1/8W 5% 0805 PANASONIC DIGIKEY P470KATR-ND
24 1 MM74HC00M U1 IC, SMT, 74HC00
QUAD 2 IN NAND
(SO-14)
FAIRCHILD
SEMICONDUCTOR DIGIKEY MM74HC00M-
ND
25 3 NDS9942 U2, U5, U6 IC, SMT, 9942 MOS-
FET N-CH & P-CH
20V (SO-8)
FAIRCHILD
SEMICONDUCTOR DIGIKEY NDS9942TR-
ND
26 1 MM74HC86MX U3 IC, SMT, 74HC86,
QUAD XOR GATE
(SO-14)
FAIRCHILD
SEMICONDUCTOR DIGIKEY
27 1 PIC16C73A /P U4 IC , PIC16C73A /P,
PLASTIC DI P, 2 8 P,
0.300
MICROCHIP
28 1 MAX232ACSE U7 IC, MAX232ACSE
DUAL RS-232
TRANSMITTER/
RCVR, (SO-16)
MAXIM DIGIKEY MAX232ACSE-
ND
29 1 MC34072D U8 IC, DU AL OP AMP,
(SO-8) MOTOROLA
30 1 L7805CV U9 IC, REG, +5V, 1.5A,
10%,
TO-220
SGS THOMSON MOUSER 511-L7805CV
31 1 EFO-EC8004A4 Y1 OSC, 8.00 MHz CER
RESONATOR W/
CAP 3 PIN
PANASONIC DIGIKEY PX800-ND
32 1 MCT0003-000 L1 INDUCTOR, 162 µH CORNEL DUBILIER
33 1 DE9S-FRS P2 CONN, D-SUB 9P
RECPT RT ANGLE SPC TECHNOL-
OGY
34 1 DJ005B P1 JACK, POWER,
2.5mm DC PC
MOUNT
LZR
ELECTRONICS
Item # Qty Part # Reference
Designator Part Description Manufacturer Vendor Vendor Part #
1998 Microchip Technology Inc. DS51139A-page 129
microID™ 125
k
Hz Design Guide
8.0 PROGRAMMER SOURCE CODE FOR PIC16C73
; #=#=#=#=#=#=#=#=#=#=# PROJECT Microchip Programmer Reader #=#=#=#=#=#=#=#=#=#=#
; #=#=#=#=#=#=#=#=#=#=# 16C73A module #=#=#=#=#=#=#=#=#=#=#
; rfgopr5.asm
; PIC16C73A running at 8.5MHz, Ti = 0.47us
; Tcy = 16 Ti
; ///////////////////////////////////////////////////////////////////////////
; Revision history
; ///////////////////////////////////////////////////////////////////////////
;
; Ver Date Comment
;
; 1.00 10/24/97 Shannon/Hugh first pass
; 1.04 13 Feb 98 ADDED TIMEOUT TO TESTMOD
;
LISTP=PIC16C73A
INCLUDE “P16C73A.INC”
__config b’11111111110010’
; Code Protect off, Brown-out detect on, Power-up timer on, WDT off,
; HS oscillator
constant StartPORTA = b’000000’
constant StartTRISA = b’010111’
#define _LED1 PORTB,4
#define _LED2 PORTB,5
#define _BUZZ1 PORTB,6
constant StartPORTB = b’00010010’
constant StartTRISB = b’00000100’
constant StartOPTION = b’10001000’
; Pullups disabled, TMR0 internal, WDT*1
COUNT1EQU0x20 ; COUNT REGISTER
DATA0EQU0x21
DATA1EQU0x22
DATA2EQU0x23
DATA3EQU0x24
DATA4EQU0x25
DATA5EQU0x26
DATA6EQU0x27
DATA7EQU0x28
DATA8EQU0x29
DATA9EQU0x2A
DATAAEQU0x2B
DATABEQU0x2C
DATACEQU0x2D
DATADEQU0x2E
DATAEEQU0x2F
DATAFEQU0x30
BIT EQU 0x31
OVERPROEQU0x32
DELAY1EQU0x33
DELAY2EQU0x34
DelayReg?H = h’35’
DelayReg?L = h’36’
CycleCtr?H = h’37’
CycleCtr?L = h’38’
TimerHi = h’39’
TimerMid = h’3A’
TimerLo = h’3B’
BitCtr = h’3C’
BO3 = h’3D’
RxByte = h’3E’
TxByte = h’3F’
ByteCtr = h’40’
microID™ 125
k
Hz Design Guide
DS51139A-page 130 1998 Microchip Technology Inc.
NoiseTimeout = h’41’
SampTimeout = h’42’
CycleCtr2?L = h’43’
CycleCtr2?H = h’44’
#define _RAW_DATA PORTA,4
#define _RS232OUT PORTC,6
#define _CARRY STATUS,0
#define _TMR2ON T2CON,2
#define _RS232IN PORTC,7
#define _ZERO STATUS,2
#define _COIL_PWR_0 PORTB,3 ; cycle at 30ms period (1=low power)
#define _COIL_EN PORTB,1
SKIP macro
BTFSC PORTA,7
endm
; ***** Reset Vector
org h’000’
CLRF STATUS
CLRF PCLATH
CLRF INTCON
GOTO RESET_A
; ***** Interrupt Vector - no interrupts yet
org h’004’
CLRF STATUS
CLRF PCLATH
GOTO RESET_A
RS232StopBit ;[0] Delay >=208 cycles with _RS232OUT high
BSF _RS232OUT ; |
MOVLW d’208’-d’12’+d’40’; |
DelayW12 ;[0] Delay 12+W cycles
MOVWF DelayReg?L ; |
Delay1 ;[0] Delay 11+Delay cycles
MOVLW d’4’ ; |
Delay1L ; |
SUBWF DelayReg?L,f ; |
BTFSC _CARRY ; |
GOTO Delay1L ; |
COMF DelayReg?L,W ; |
ADDWF PCL,f ; |
Delay07 ;[0] Delay 7 cycles
NOP ; |
Delay06 ;[0] Delay 6 cycles
NOP ; |
Delay05 ;[0] Delay 5 cycles
NOP ; |
Delay04 ;[0] Delay 4 cycles
RETLW h’00’ ; |
RESET_A
CLRWDT ; Initialise registers, clear watchdog timer
CLRF STATUS ; | Access register page 0
CLRF FSR ; | FSR=#0
MOVLW StartPORTA ; | Initialise PORT registers
MOVWF PORTA ; | |
MOVLW StartPORTB ; | |
MOVWF PORTB ; | |
CLRF INTCON ; | Interrupts off
MOVLW b’110001’ ; | TMR1 prescale *8, on
MOVWF T1CON ; | |
MOVLW b’0000000’ ; | TMR2 postscale *1, off, prescale *1
1998 Microchip Technology Inc. DS51139A-page 131
microID™ 125
k
Hz Design Guide
MOVWF T2CON ; | |
MOVLW d’8’ ; | Duty on period = 8 Ti @@@
MOVWF CCPR1L ; | |
MOVLW b’001100’ ; | CCP1 to PWM, 0,0 extra duty time @@@
MOVWF CCP1CON ; | |
MOVLW b’00000000’ ; | A/D convertor OFF
MOVWF ADCON0 ; | |
BSF STATUS,RP0 ;^| Initialise TRIS registers
MOVLW StartTRISA ;^| |
MOVWF TRISA ;^| |
MOVLW StartTRISB ;^| |
MOVWF TRISB ;^| |
MOVLW 0x82
MOVWF TRISC
MOVLW StartOPTION ;^| Initialise OPTION register
MOVWF OPTION_REG ;^| |
MOVLW d’15’ ;^| PR2=7 (period of TMR2=16) @@@
MOVWF PR2 ;^| |
MOVLW h’03’ ;^| (It says so on page 2-584)
MOVWF PCON ;^| |
MOVLW b’110’ ;^| No analog inputs
MOVWF ADCON1 ;^| |
BCF STATUS,RP0 ; | |
; !!!!! set TRIS registers, and other hardware registers.
BCF T2CON,2; turn coil off
CLRF TMR2
BCF PORTB,3
CALL RS232On
BigLoop1
CALL RS232WaitForever
CheckRxByte
MOVF RxByte,W
XORLW ‘W’
BTFSC _ZERO
GOTO INTERRUPT
CALL RS232On
MOVLW ‘Q’
CALL RS232TxW
GOTO BigLoop1
INTERRUPT
CALL Delay07 ; LED1 on, LED2 on (orange/yellow)
BSF _LED1 ; |
CALL Delay07 ; |
BSF _LED2 ; |
CALL Delay07 ; |
INT_WAKEUP
MOVLW ‘R’
MOVWF RxByte
CALL RS232On ; delay
MOVF RxByte,W ; Transmit RxByte
CALL RS232TxW ; |
CALL RS232Rx ; Read byte from RS-232
BTFSC _CARRY ; | (if timeout, goto INT_END)
GOTO INT_END ; |
MOVF RxByte,W ; if (RxByte<>#’T’)
XORLW ‘T’ ; |
BTFSS _ZERO ; |
GOTO CheckRxByte ; { goto CheckRxByte }
MOVLW d’10’
microID™ 125
k
Hz Design Guide
DS51139A-page 132 1998 Microchip Technology Inc.
MOVWF CycleCtr?H
CLRF CycleCtr?L
Top1 BCFPORTB,3; SET FOR LOW VOLTAGE
CALLDELAY ; CALL A SMALL DELAY
GAP1; THIS IS THE ROUTINE THAT SETS THE GAP
BCF PORTB,3
CALL DELAY
BSF T2CON,2 ; TURN ON THE COIL
MOVLW0x32 ; MOVE 32 HEX TO W, NUMBER CYCLES BEFORE A GAP
MOVWFCOUNT1; MOVW W INTO COUNT1
LOOP11DECFSZCOUNT1,1; DECREMENT COUNT 1 UNTIL IT IS ZERO
GOTOLOOP11
BCF T2CON,2 ; TURN OFF THE COIL
MOVLW0x40 ; MOVE 10 HEX TO W, DURATION OF GAP
MOVWFCOUNT1; MOVW W INTO COUNT1
LOOP21DECFSZCOUNT1,1; DECREMENT COUNT 1 UNTIL IT IS ZERO
GOTOLOOP21
BSF T2CON,2 ; TURN THE COIL BACK ON
CALL TWC ; CALL A DELAY FOR AMP TO SETTLE
CALL TWC
CALL TWC
CALL TWC
CALL TWC
WaitFall1 ; Wait for falling edge
WaitFall1A ; | Wait for high
MOVLW d’200’ ; | | Set timeout
MOVWF DelayReg?H ; | | |
CLRF DelayReg?L ; | | |
WaitFall1AL ; | | { {
DECFSZ DelayReg?L,f ; | | if (timeout)
SKIP ; | | |
DECFSZ DelayReg?H,f ; | | |
SKIP ; | | |
GOTO INT_ErrorN ; | | { goto INT_ErrorN }
BTFSS _RAW_DATA ; | | } until (_RAW_DATA==#1)
GOTO WaitFall1AL ; | | |
NOP ; | | |
DECFSZ DelayReg?L,f ; | | if (timeout)
SKIP ; | | |
DECFSZ DelayReg?H,f ; | | |
SKIP ; | | |
GOTO INT_ErrorN ; | | { goto INT_ErrorN }
BTFSS _RAW_DATA ; | | } until (_RAW_DATA==#1)
GOTO WaitFall1AL ; | |
WaitFall1B ; | Wait for low
MOVLW d’200’ ; | | Set timeout
MOVWF DelayReg?H ; | | |
CLRF DelayReg?L ; | | |
WaitFall1BL ; | | { {
DECFSZ DelayReg?L,f ; | | if (timeout)
SKIP ; | | |
DECFSZ DelayReg?H,f ; | | |
SKIP ; | | |
GOTO INT_ErrorN ; | | { goto INT_ErrorN }
BTFSC _RAW_DATA ; | | } until (_RAW_DATA==#0)
1998 Microchip Technology Inc. DS51139A-page 133
microID™ 125
k
Hz Design Guide
GOTO WaitFall1BL ; | | |
NOP ; | | |
DECFSZ DelayReg?L,f ; | | if (timeout)
SKIP ; | | |
DECFSZ DelayReg?H,f ; | | |
SKIP ; | | |
GOTO INT_ErrorN ; | | { goto INT_ErrorN }
BTFSC _RAW_DATA ; | | } until (_RAW_DATA==#0)
GOTO WaitFall1BL ; | | |
CLRF DelayReg?L ; Clear timer
WaitFall2 ; Time falling edge
WaitFall2A ; | Wait for high
WaitFall2AL ; | | { {
NOP ;
NOP ;
INCF DelayReg?L,f ; | | Increment timer
BTFSC DelayReg?L,7 ; | | if timeout,
GOTO INT_ErrorN ; | | { goto INT_ErrorN }
BTFSS _RAW_DATA ; | | } until (_RAW_DATA==#1)
GOTO WaitFall2AL ; | | |
NOP ; | | |
NOP ;
NOP ;
INCF DelayReg?L,f ; | | Increment timer
BTFSC DelayReg?L,7 ; | | if timeout,
GOTO INT_ErrorN ; | | { goto INT_ErrorN }
BTFSS _RAW_DATA ; | | } until (_RAW_DATA==#1)
GOTO WaitFall2AL ; | |
NOP ;
WaitFall2B ; | Wait for low
WaitFall2BL ; | | { {
NOP ;
NOP ;
INCF DelayReg?L,f ; | | Increment timer
BTFSC DelayReg?L,7 ; | | if timeout,
GOTO INT_ErrorN ; | | { goto INT_ErrorN }
BTFSC _RAW_DATA ; | | } until (_RAW_DATA==#0)
GOTO WaitFall2BL ; | | |
NOP ; | | |
NOP ;
NOP ;
INCF DelayReg?L,f ; | | Increment timer
BTFSC DelayReg?L,7 ; | | if timeout,
GOTO INT_ErrorN ; | | { goto INT_ErrorN }
BTFSC _RAW_DATA ; | | } until (_RAW_DATA==#0)
GOTO WaitFall2BL ; | | |
; DelayReg?L*8Ti = period of signal
; period of _RAW_DATA on FSK = Tcy*10 = Ti*160
; DelayReg?L = 20 if FSK present
; if period does not match FSK, goto INT_ErrorN
MOVF DelayReg?L,W ; | if (DelayReg?L<14)
ADDLW low(0-d’14’) ; | |
BTFSS _CARRY ; | |
GOTO INT_ErrorN ; | { goto INT_ErrorN }
ADDLW low(d’14’-d’22’); | if (DelayReg?L>=22)
BTFSC _CARRY ; | |
GOTO INT_ErrorN ; | { goto INT_ErrorN }
MOVLW d’7’ ; CycleCtr > 13*128=1664
MOVWF CycleCtr?H ; |
MOVLW d’164’ ; |
MOVWF CycleCtr?L ; |
TestGotLo
DECFSZ CycleCtr?L,f
SKIP
microID™ 125
k
Hz Design Guide
DS51139A-page 134 1998 Microchip Technology Inc.
DECFSZ CycleCtr?H,f
SKIP
GOTO INT_ErrorN
MOVLW 0x20
MOVWF COUNT1
BTFSS _RAW_DATA
GOTO TestGotHi
TestGotLoLoop
BTFSS _RAW_DATA
GOTO TestGotHi
DECFSZ COUNT1,1
GOTO TestGotLoLoop
GOTO MChip_Prog
TestGotHi
MOVLW 0x20
MOVWF COUNT1
BTFSC _RAW_DATA
GOTO TestGotLo
TestGotHiLoop
BTFSC _RAW_DATA
GOTO TestGotLo
DECFSZ COUNT1,1
GOTO TestGotHiLoop
;END TEST FOR NO MODULATION
MChip_Prog
BCF _TMR2ON
CALL TWC
CLRF DATA0
CLRF DATA1
CLRF DATA2
CLRF DATA3
CLRF DATA4
CLRF DATA5
CLRF DATA6
CLRF DATA7
CLRF DATA8
CLRF DATA9
CLRF DATAA
CLRF DATAB
CLRF DATAC
CLRF DATAD
CLRF DATAE
CLRF DATAF
MOVLW ‘Y’ ; RxByte=’Y’
MOVWF RxByte ; |
MOVLW DATAF ; FSR=#DATAF
MOVWF FSR ; |
MOVLW h’20’ ; ByteCtr=#h’20’
MOVWF ByteCtr ; |
RS_ByteLoop ; {
CALL RS232On ; delay
MOVF RxByte,W ; Transmit RxByte on RS-232
CALL RS232TxW ; |
CALL RS232Rx ; Read RS-232 byte into RxByte
BTFSC _CARRY ; |(if timeout, goto INT_END)
GOTO INT_END ; |
MOVF RxByte,W ; BO3=RxByte
MOVWF BO3 ; |
MOVLW h’30’ ; if (BO3<#h’30’)
SUBWF BO3,W ; |
BTFSS _CARRY ; |
GOTO CheckRxByte ; { goto CheckRxByte }
1998 Microchip Technology Inc. DS51139A-page 135
microID™ 125
k
Hz Design Guide
MOVWF BO3 ; BO3=BO3-#h’30’
MOVLW h’3A’-h’30’ ; if (BO3>=#h’3A’-#h’30’)
SUBWF BO3,W ; |
BTFSS _CARRY ; |
GOTO RSDataJ1 ; {
MOVWF BO3 ; BO3=BO3-#h’3A’+#h’30’
MOVLW h’41’-h’3A’ ; if (BO3<#h’41’-#h’3A’)
SUBWF BO3,W ; |
BTFSS _CARRY ; |
GOTO CheckRxByte ; { goto CheckRxByte }
MOVWF BO3 ; BO3=BO3-#h’41’+#h’3A’
MOVLW h’47’-h’41’ ; if (BO3>=#h’47’-#h’41’)
SUBWF BO3,W ; |
BTFSC _CARRY ; |
GOTO CheckRxByte ; { goto CheckRxByte }
MOVLW h’0A’ ; BO3=BO3+#h’0A’
ADDWF BO3,f ; |
RSDataJ1 ; }
SWAPF BO3,W ; W = { BO3 swapped if ByteCtr,0==#0
BTFSC ByteCtr,0 ; | { BO3 if ByteCtr,0==#1
MOVF BO3,W ; |
IORWF INDF,f ; INDF=INDF OR W
BTFSC ByteCtr,0 ; if (ByteCtr,0==#1)
DECF FSR,f ; { FSR=FSR-#1 }
DECFSZ ByteCtr,f ; DEC ByteCtr
GOTO RS_ByteLoop ; } until (ByteCtr==#0)
CALL RS232On ; delay
MOVF RxByte,W ; Transmit RxByte on RS-232
CALL RS232TxW ; |
CALL RS232Rx ; Read RS-232 byte into RxByte
BTFSC _CARRY ; |( if timeout, goto INT_END)
GOTO INT_END ; |
MOVF RxByte,W ; if (RxByte!=#’V’)
XORLW ‘V’ ; |
BTFSS _ZERO ; |
GOTO CheckRxByte ; { goto CheckRxByte }
; ********
Top BCF PORTB,3 ; SET FOR LOW VOLTAGE
CALLDELAY ; CALL A SMALL DELAY
GAP ; THIS IS THE ROUTINE THAT SETS THE GAP
BCF PORTB,3
CALL DELAY
BSF T2CON,2 ; TURN ON THE COIL
MOVLW0x32 ; MOVE 32 HEX TO W, NUMBER CYCLES BEFORE A GAP
MOVWFCOUNT1; MOVW W INTO COUNT1
LOOP1DECFSZCOUNT1,1; DECREMENT COUNT 1 UNTIL IT IS ZERO
GOTOLOOP1
BCF T2CON,2 ; TURN OFF THE COIL
MOVLW0x40 ; MOVE 10 HEX TO W, DURATION OF GAP
MOVWFCOUNT1; MOVW W INTO COUNT1
LOOP2DECFSZCOUNT1,1; DECREMENT COUNT 1 UNTIL IT IS ZERO
GOTOLOOP2
BSF T2CON,2 ; TURN THE COIL BACK ON
microID™ 125
k
Hz Design Guide
DS51139A-page 136 1998 Microchip Technology Inc.
MOVLWd’8’; MOVE 5 INTO THE W REGISTER
MOVWFOVERPRO; THIS IS THE NUMBER OF OVERPROGRAMMING
CALL TWC ; CALL A DELAY FOR AMP TO SETTLE
CALL TWC
CALL TWC
CALL TWC
CALL TWC
MODING CALL TESTMOD
CALL PROGRAM
MOVLW 0x60
MOVWF COUNT1
BIGDLY CALL TWC ; CALL A DELAY TO ALLOW THE AMP TO SETTLE
DECFSZ COUNT1,f
GOTO BIGDLY
DECFSZ OVERPRO,1 ; DECREMENT THE OVERPROGRAMMING NUMBER
GOTOMODING ; GOTO LOOK FOR THE MODULATION TO STOP
GOTOVERIFY
;***************************************
VERIFY
CALL TESTMOD ; Wait for modulation to stop
;% 167Ti of constant _RAW_DATA
StartWatch ; Wait >~Ttag (for mod to start again)
MOVLW h’00’ ; Delay >~262144Ti
MOVWF DelayReg?H ; |
VerifyD1a ; |
MOVLW h’FF’ ; | delay 1021Ti
MOVWF DelayReg?L ; | |
VerifyD1b ; | |
CLRWDT ; | |
DECFSZ DelayReg?L,f ; | |
GOTO VerifyD1b ; | |
DECFSZ DelayReg?H,f ; |
GOTO VerifyD1a ; |
StopWatch ; |
CLRF BitCtr ; BitCtr=#128
BSF BitCtr,7 ; |
VerifyL1 ; {
;% reftime-1345
CLRF CycleCtr?L
;% reftime-1344
;% reftime-3-10*6-183*7
MOVLW d’10’ ; set NoiseTimeout
MOVWF NoiseTimeout ; |
;% reftime-1-10*6-183*7
;% reftime-1-NTO*6-183*7
MOVLW d’183’ ; set SampTimeout to 80Tcy
MOVWF SampTimeout ; |
;% reftime+1-NTO*6-183*7
;% reftime+1-NTO*6-STO*7
BTFSC _RAW_DATA
GOTO VerS1
NOP
VerS0
;% reftime+4-NTO*6-STO*7
1998 Microchip Technology Inc. DS51139A-page 137
microID™ 125
k
Hz Design Guide
DECFSZ NoiseTimeout,f
SKIP
GOTO VerFail
BTFSC _RAW_DATA
GOTO VerS1
VerGot0
;% reftime+3-NTO*6-STO*7
VerGot0a
;% reftime+3-NTO*6-STO*7
CLRWDT
DECFSZ SampTimeout,f
SKIP
GOTO SampleDone
BTFSS _RAW_DATA
GOTO VerGot0
NOP
VerGot0b
;% reftime+3-NTO*6-STO*7
CLRWDT
DECFSZ SampTimeout,f
SKIP
GOTO SampleDone
BTFSS _RAW_DATA
GOTO VerGot0
NOP
VerGotRise
;% reftime+3-NTO*6-STO*7
CLRWDT
DECFSZ SampTimeout,f
SKIP
GOTO SampleDone
INCF CycleCtr?L,f
GOTO VerGot1
VerS1
;% reftime+4-NTO*6-STO*7
DECFSZ NoiseTimeout,f
SKIP
GOTO VerFail
BTFSS _RAW_DATA
GOTO VerS0
VerGot1
;% reftime+3-NTO*6-STO*7
VerGot1a
;% reftime+3-NTO*6-STO*7
CLRWDT
DECFSZ SampTimeout,f
SKIP
GOTO SampleDone
BTFSC _RAW_DATA
GOTO VerGot1
NOP
VerGot1b
;% reftime+3-NTO*6-STO*7
CLRWDT
DECFSZ SampTimeout,f
SKIP
GOTO SampleDone
BTFSC _RAW_DATA
GOTO VerGot1
NOP
VerGotFall
;% reftime+3-NTO*6-STO*7
CLRWDT
DECFSZ SampTimeout,f
SKIP
microID™ 125
k
Hz Design Guide
DS51139A-page 138 1998 Microchip Technology Inc.
GOTO SampleDone
INCF CycleCtr?L,f
GOTO VerGot0
SampleDone
;% reftime+1-NTO*6-STO*7
;& STO=0
;% reftime+1-NTO*6
NoiseMargin
;% reftime+1-NTO*6
NOP
NOP
NOP
DECFSZ NoiseTimeout,f
GOTO NoiseMargin
;% reftime+0-NTO*6
;% NTO=0
;% reftime+0
BTFSC DATAF,7
GOTO Verify1
NOP
Verify0
;% 3 from ref time
; if ‘0’ bit, _DATA_IN cycles 10 times in 80 Tcy
; CycleCtr?L should be 20
MOVF CycleCtr?L,W
ADDLW low(0-d’18’)
BTFSS _CARRY
GOTO INT_Failure
ADDLW low(d’18’-d’22’)
BTFSS _CARRY
GOTO Bit_Verified
GOTO INT_Failure
Verify1
;% 3 from ref time
; if ‘1’ bit, _DATA_IN cycles 8 times in 80Tcy
; CycleCtr?L should be 16
MOVF CycleCtr?L,W
ADDLW low(0-d’14’)
BTFSS _CARRY
GOTO INT_Failure
ADDLW low(d’14’-d’18’)
BTFSS _CARRY
GOTO Bit_Verified
GOTO INT_Failure
Bit_Verified
;% 11 from ref time
BCF _CARRY
BTFSC DATAF,7
BSF _CARRY
RLF DATA0,f
RLF DATA1,f
RLF DATA2,f
RLF DATA3,f
RLF DATA4,f
RLF DATA5,f
RLF DATA6,f
RLF DATA7,f
RLF DATA8,f
RLF DATA9,f
RLF DATAA,f
RLF DATAB,f
1998 Microchip Technology Inc. DS51139A-page 139
microID™ 125
k
Hz Design Guide
RLF DATAC,f
RLF DATAD,f
RLF DATAE,f
RLF DATAF,f
;% 30 from ref time
MOVLW d’167’ ; Delay 670Ti
MOVWF DelayReg?L ; |
NOP ; |
VerDelay ; |
CLRWDT ; |
DECFSZ DelayReg?L,f ; |
GOTO VerDelay ; |
;% 700 from ref time
;% (ref times 128*16Ti apart = 2048Ti apart)
;% -1348 from ref time
DECFSZ BitCtr,f ; DEC BitCtr
GOTO VerifyL1 ; } until (BitCtr==#0)
;***************************************
INT_Success
CALL RS232On
MOVLW ‘y’
CALL RS232TxW
GOTO BigLoop1
VerFail
INT_Failure
CALL RS232On
MOVLW ‘n’
CALL RS232TxW
GOTO BigLoop1
INT_END ; RS-232 TIMEOUT
NOP
GOTO BigLoop1
INT_ErrorN
CALL RS232On
MOVLW ‘N’
CALL RS232TxW
GOTO BigLoop1
DELAYMOVLW0x05
MOVWFDELAY1
HOLD4DECFSZDELAY1,1
GOTOHOLD4
RETLW0
; TWC lasts
TWC MOVLW0xB0 ; WRITE CYCLE TIMER SUBROUTINE
MOVWFDELAY1
HOLD1MOVLW0x02
MOVWFDELAY2
HOLD2DECFSZDELAY2,1
GOTOHOLD2
DECFSZDELAY1,1
GOTOHOLD1
RETLW0
BUFFERMOVLW0x58
MOVWFDELAY1
microID™ 125
k
Hz Design Guide
DS51139A-page 140 1998 Microchip Technology Inc.
HOLD3DECFSZDELAY1,1
GOTOHOLD3
NOP
NOP
RETLW0
TESTMOD; THIS ROUTINE TESTS THE RAW DATA LINE TO SEE IF THE
; PART IS MODULATING OR NOT
; This routine returns when _RAW_DATA stays constant for some time
; some time = 7Ti+32*5Ti = 167Ti = 10.4375Tcy
MOVLW d’7’ ; CycleCtr2 > 13*128=1664
MOVWF CycleCtr2?H ; |
MOVLW d’164’ ; |
MOVWF CycleCtr2?L ; |
TestModLo
DECFSZ CycleCtr2?L,f
SKIP
DECFSZ CycleCtr2?H,f
SKIP
GOTO INT_Failure
MOVLW 0x20
MOVWF COUNT1
BTFSS _RAW_DATA
GOTO TestModHi
TestModLoLoop
BTFSS _RAW_DATA
GOTO TestModHi
DECFSZ COUNT1,1
GOTO TestModLoLoop
RETLW 0
TestModHi
MOVLW 0x20
MOVWF COUNT1
BTFSC _RAW_DATA
GOTO TestModLo
TestModHiLoop
BTFSC _RAW_DATA
GOTO TestModLo
DECFSZ COUNT1,1
GOTO TestModHiLoop
;END TEST FOR NO MODULATION
RETLW 0
PROGRAM BCFPORTB,3; CLEAR THE HIGH VOLTAGE
MOVLW0x07; MOVW 7 HEX INTO W
MOVWFBIT ; MOVE THIS INTO THE BIT COUNTER
WRITEFBTFSSDATAF,7 ; TEST MOST BYTE
BSF PORTB,3 ; SET THE HIGH VOLTAGE
CALLTWC ; CALL THE WRITE CYCLE TIMER
BCF STATUS,C ; CLEAR THE CARRY BIT
BTFSC DATAF,7 ; TEST THE MSB
BSF STATUS,C ; SET THE CARRY BIT
RLF DATAF,1 ; ROTATE DATAF
BCFPORTB,3; CLEAR THE HIGH VOLTAGE
CALL BUFFER; CALL THE BUFFER TIMER
DECF BIT,1; DECREMENT BIT, SKIP IF ZERO
BTFSS BIT,7 ; SKIP IF SET
GOTOWRITEF; GOTO WRITEF IF BIT IS NOT EQUAL TO ZERO
NOP
NOP
NOP
NOP
1998 Microchip Technology Inc. DS51139A-page 141
microID™ 125
k
Hz Design Guide
NOP
NOP
NOP
MOVLW0x07; MOVW 7 HEX INTO W
MOVWFBIT ; MOVE THIS INTO THE BIT COUNTER
WRITEEBTFSSDATAE,7 ; TEST MOST BYTE
BSF PORTB,3 ; SET THE HIGH VOLTAGE
CALLTWC ; CALL THE WRITE CYCLE TIMER
BCF STATUS,C ; CLEAR THE CARRY BIT
BTFSC DATAE,7 ; TEST THE MSB
BSF STATUS,C ; SET THE CARRY BIT
RLF DATAE,1 ; ROTATE DATAF
BCFPORTB,3; CLEAR THE HIGH VOLTAGE
CALL BUFFER; CALL THE BUFFER TIMER
DECF BIT,1; DECREMENT BIT, SKIP IF ZERO
BTFSS BIT,7 ; SKIP IF SET
GOTOWRITEE; GOTO WRITEE IF BIT IS NOT EQUAL TO ZERO
NOP
NOP
NOP
NOP
NOP
NOP
NOP
MOVLW0x07 ; MOVW 7 HEX INTO W
MOVWFBIT ; MOVE THIS INTO THE BIT COUNTER
WRITEDBTFSSDATAD,7 ; TEST MOST BYTE
BSF PORTB,3 ; SET THE HIGH VOLTAGE
CALLTWC ; CALL THE WRITE CYCLE TIMER
BCF STATUS,C ; CLEAR THE CARRY BIT
BTFSC DATAD,7 ; TEST THE MSB
BSF STATUS,C ; SET THE CARRY BIT
RLF DATAD,1 ; ROTATE DATAF
BCFPORTB,3; CLEAR THE HIGH VOLTAGE
CALL BUFFER; CALL THE BUFFER TIMER
DECF BIT,1; DECREMENT BIT, SKIP IF ZERO
BTFSS BIT,7 ; SKIP IF SET
GOTOWRITED; GOTO WRITEF IF BIT IS NOT EQUAL TO ZERO
NOP
NOP
NOP
NOP
NOP
NOP
NOP
MOVLW0x07 ; MOVW 7 HEX INTO W
MOVWFBIT ; MOVE THIS INTO THE BIT COUNTER
WRITECBTFSSDATAC,7 ; TEST MOST BYTE
BSF PORTB,3 ; SET THE HIGH VOLTAGE
CALLTWC ; CALL THE WRITE CYCLE TIMER
BCF STATUS,C ; CLEAR THE CARRY BIT
BTFSC DATAC,7 ; TEST THE MSB
BSF STATUS,C ; SET THE CARRY BIT
RLF DATAC,1 ; ROTATE DATAF
BCFPORTB,3; CLEAR THE HIGH VOLTAGE
CALL BUFFER; CALL THE BUFFER TIMER
DECF BIT,1; DECREMENT BIT, SKIP IF ZERO
BTFSS BIT,7 ; SKIP IF SET
GOTOWRITEC; GOTO WRITEC IF BIT IS NOT EQUAL TO ZERO
NOP
NOP
NOP
NOP
microID™ 125
k
Hz Design Guide
DS51139A-page 142 1998 Microchip Technology Inc.
NOP
NOP
NOP
MOVLW0x07 ; MOVW 7 HEX INTO W
MOVWFBIT ; MOVE THIS INTO THE BIT COUNTER
WRITEBBTFSSDATAB,7 ; TEST MOST BYTE
BSF PORTB,3 ; SET THE HIGH VOLTAGE
CALLTWC ; CALL THE WRITE CYCLE TIMER
BCF STATUS,C ; CLEAR THE CARRY BIT
BTFSC DATAB,7 ; TEST THE MSB
BSF STATUS,C ; SET THE CARRY BIT
RLF DATAB,1 ; ROTATE DATAF
BCFPORTB,3; CLEAR THE HIGH VOLTAGE
CALL BUFFER; CALL THE BUFFER TIMER
DECF BIT,1; DECREMENT BIT, SKIP IF ZERO
BTFSS BIT,7 ; SKIP IF SET
GOTOWRITEB; GOTO WRITEB IF BIT IS NOT EQUAL TO ZERO
NOP
NOP
NOP
NOP
NOP
NOP
NOP
MOVLW0x07 ; MOVW 7 HEX INTO W
MOVWFBIT ; MOVE THIS INTO THE BIT COUNTER
WRITEABTFSSDATAA,7 ; TEST MOST BYTE
BSF PORTB,3 ; SET THE HIGH VOLTAGE
CALLTWC ; CALL THE WRITE CYCLE TIMER
BCF STATUS,C ; CLEAR THE CARRY BIT
BTFSC DATAA,7 ; TEST THE MSB
BSF STATUS,C ; SET THE CARRY BIT
RLF DATAA,1 ; ROTATE DATAF
BCFPORTB,3; CLEAR THE HIGH VOLTAGE
CALL BUFFER; CALL THE BUFFER TIMER
DECF BIT,1; DECREMENT BIT, SKIP IF ZERO
BTFSS BIT,7 ; SKIP IF SET
GOTOWRITEA; GOTO WRITEA IF BIT IS NOT EQUAL TO ZERO
NOP
NOP
NOP
NOP
NOP
NOP
NOP
MOVLW0x07 ; MOVW 7 HEX INTO W
MOVWFBIT ; MOVE THIS INTO THE BIT COUNTER
WRITE9BTFSSDATA9,7 ; TEST MOST BYTE
BSF PORTB,3 ; SET THE HIGH VOLTAGE
CALLTWC ; CALL THE WRITE CYCLE TIMER
BCF STATUS,C ; CLEAR THE CARRY BIT
BTFSC DATA9,7 ; TEST THE MSB
BSF STATUS,C ; SET THE CARRY BIT
RLF DATA9,1 ; ROTATE DATAF
BCFPORTB,3; CLEAR THE HIGH VOLTAGE
CALL BUFFER; CALL THE BUFFER TIMER
DECF BIT,1; DECREMENT BIT, SKIP IF ZERO
BTFSS BIT,7 ; SKIP IF SET
GOTOWRITE9; GOTO WRITE9 IF BIT IS NOT EQUAL TO ZERO
NOP
NOP
NOP
NOP
1998 Microchip Technology Inc. DS51139A-page 143
microID™ 125
k
Hz Design Guide
NOP
NOP
NOP
MOVLW0x07 ; MOVW 7 HEX INTO W
MOVWFBIT ; MOVE THIS INTO THE BIT COUNTER
WRITE8BTFSSDATA8,7 ; TEST MOST BYTE
BSF PORTB,3 ; SET THE HIGH VOLTAGE
CALLTWC ; CALL THE WRITE CYCLE TIMER
BCF STATUS,C ; CLEAR THE CARRY BIT
BTFSC DATA8,7 ; TEST THE MSB
BSF STATUS,C ; SET THE CARRY BIT
RLF DATA8,1 ; ROTATE DATAF
BCFPORTB,3; CLEAR THE HIGH VOLTAGE
CALL BUFFER; CALL THE BUFFER TIMER
DECF BIT,1; DECREMENT BIT, SKIP IF ZERO
BTFSS BIT,7 ; SKIP IF SET
GOTOWRITE8; GOTO WRITE8 IF BIT IS NOT EQUAL TO ZERO
NOP
NOP
NOP
NOP
NOP
NOP
NOP
MOVLW0x07; MOVW 7 HEX INTO W
MOVWFBIT ; MOVE THIS INTO THE BIT COUNTER
WRITE7BTFSSDATA7,7 ; TEST MOST BYTE
BSF PORTB,3 ; SET THE HIGH VOLTAGE
CALLTWC ; CALL THE WRITE CYCLE TIMER
BCF STATUS,C ; CLEAR THE CARRY BIT
BTFSC DATA7,7 ; TEST THE MSB
BSF STATUS,C ; SET THE CARRY BIT
RLF DATA7,1 ; ROTATE DATAF
BCFPORTB,3; CLEAR THE HIGH VOLTAGE
CALL BUFFER; CALL THE BUFFER TIMER
DECF BIT,1; DECREMENT BIT, SKIP IF ZERO
BTFSS BIT,7 ; SKIP IF SET
GOTOWRITE7; GOTO WRITE7 IF BIT IS NOT EQUAL TO ZERO
NOP
NOP
NOP
NOP
NOP
NOP
NOP
MOVLW0x07 ; MOVW 7 HEX INTO W
MOVWFBIT ; MOVE THIS INTO THE BIT COUNTER
WRITE6BTFSSDATA6,7 ; TEST MOST BYTE
BSF PORTB,3 ; SET THE HIGH VOLTAGE
CALLTWC ; CALL THE WRITE CYCLE TIMER
BCF STATUS,C ; CLEAR THE CARRY BIT
BTFSC DATA6,7 ; TEST THE MSB
BSF STATUS,C ; SET THE CARRY BIT
RLF DATA6,1 ; ROTATE DATAF
BCFPORTB,3; CLEAR THE HIGH VOLTAGE
CALL BUFFER; CALL THE BUFFER TIMER
DECF BIT,1; DECREMENT BIT, SKIP IF ZERO
BTFSS BIT,7 ; SKIP IF SET
GOTOWRITE6; GOTO WRITE6 IF BIT IS NOT EQUAL TO ZERO
NOP
NOP
NOP
NOP
microID™ 125
k
Hz Design Guide
DS51139A-page 144 1998 Microchip Technology Inc.
NOP
NOP
NOP
MOVLW0x07 ; MOVW 7 HEX INTO W
MOVWFBIT ; MOVE THIS INTO THE BIT COUNTER
WRITE5BTFSSDATA5,7 ; TEST MOST BYTE
BSF PORTB,3 ; SET THE HIGH VOLTAGE
CALLTWC ; CALL THE WRITE CYCLE TIMER
BCF STATUS,C ; CLEAR THE CARRY BIT
BTFSC DATA5,7 ; TEST THE MSB
BSF STATUS,C ; SET THE CARRY BIT
RLF DATA5,1 ; ROTATE DATAF
BCFPORTB,3; CLEAR THE HIGH VOLTAGE
CALL BUFFER; CALL THE BUFFER TIMER
DECF BIT,1; DECREMENT BIT, SKIP IF ZERO
BTFSS BIT,7 ; SKIP IF SET
GOTOWRITE5; GOTO WRITE5 IF BIT IS NOT EQUAL TO ZERO
NOP
NOP
NOP
NOP
NOP
NOP
NOP
MOVLW0x07 ; MOVW 7 HEX INTO W
MOVWFBIT ; MOVE THIS INTO THE BIT COUNTER
WRITE4BTFSSDATA4,7 ; TEST MOST BYTE
BSF PORTB,3 ; SET THE HIGH VOLTAGE
CALLTWC ; CALL THE WRITE CYCLE TIMER
BCF STATUS,C ; CLEAR THE CARRY BIT
BTFSC DATA4,7 ; TEST THE MSB
BSF STATUS,C ; SET THE CARRY BIT
RLF DATA4,1 ; ROTATE DATAF
BCFPORTB,3; CLEAR THE HIGH VOLTAGE
CALL BUFFER; CALL THE BUFFER TIMER
DECF BIT,1; DECREMENT BIT, SKIP IF ZERO
BTFSS BIT,7 ; SKIP IF SET
GOTOWRITE4; GOTO WRITE4 IF BIT IS NOT EQUAL TO ZERO
NOP
NOP
NOP
NOP
NOP
NOP
NOP
MOVLW0x07 ; MOVW 7 HEX INTO W
MOVWFBIT ; MOVE THIS INTO THE BIT COUNTER
WRITE3BTFSSDATA3,7 ; TEST MOST BYTE
BSF PORTB,3 ; SET THE HIGH VOLTAGE
CALLTWC ; CALL THE WRITE CYCLE TIMER
BCF STATUS,C ; CLEAR THE CARRY BIT
BTFSC DATA3,7 ; TEST THE MSB
BSF STATUS,C ; SET THE CARRY BIT
RLF DATA3,1 ; ROTATE DATAF
BCFPORTB,3; CLEAR THE HIGH VOLTAGE
CALL BUFFER; CALL THE BUFFER TIMER
DECF BIT,1; DECREMENT BIT, SKIP IF ZERO
BTFSS BIT,7 ; SKIP IF SET
GOTOWRITE3; GOTO WRITE3 IF BIT IS NOT EQUAL TO ZERO
NOP
NOP
NOP
NOP
1998 Microchip Technology Inc. DS51139A-page 145
microID™ 125
k
Hz Design Guide
NOP
NOP
NOP
MOVLW0x07 ; MOVW 7 HEX INTO W
MOVWFBIT ; MOVE THIS INTO THE BIT COUNTER
WRITE2BTFSSDATA2,7 ; TEST MOST BYTE
BSF PORTB,3 ; SET THE HIGH VOLTAGE
CALLTWC ; CALL THE WRITE CYCLE TIMER
BCF STATUS,C ; CLEAR THE CARRY BIT
BTFSC DATA2,7 ; TEST THE MSB
BSF STATUS,C ; SET THE CARRY BIT
RLF DATA2,1 ; ROTATE DATAF
BCFPORTB,3; CLEAR THE HIGH VOLTAGE
CALL BUFFER; CALL THE BUFFER TIMER
DECF BIT,1; DECREMENT BIT, SKIP IF ZERO
BTFSS BIT,7 ; SKIP IF SET
GOTOWRITE2; GOTO WRITE2 IF BIT IS NOT EQUAL TO ZERO
NOP
NOP
NOP
NOP
NOP
NOP
NOP
MOVLW0x07 ; MOVW 7 HEX INTO W
MOVWFBIT ; MOVE THIS INTO THE BIT COUNTER
WRITE1BTFSSDATA1,7 ; TEST MOST BYTE
BSF PORTB,3 ; SET THE HIGH VOLTAGE
CALLTWC ; CALL THE WRITE CYCLE TIMER
BCF STATUS,C ; CLEAR THE CARRY BIT
BTFSC DATA1,7 ; TEST THE MSB
BSF STATUS,C ; SET THE CARRY BIT
RLF DATA1,1 ; ROTATE DATAF
BCFPORTB,3; CLEAR THE HIGH VOLTAGE
CALL BUFFER; CALL THE BUFFER TIMER
DECF BIT,1; DECREMENT BIT, SKIP IF ZERO
BTFSS BIT,7 ; SKIP IF SET
GOTOWRITE1; GOTO WRITEF IF BIT IS NOT EQUAL TO ZERO
NOP
NOP
NOP
NOP
NOP
NOP
NOP
MOVLW0x07 ; MOVW 7 HEX INTO W
MOVWFBIT ; MOVE THIS INTO THE BIT COUNTER
WRITE0BTFSSDATA0,7 ; TEST MOST BYTE
BSF PORTB,3 ; SET THE HIGH VOLTAGE
CALLTWC ; CALL THE WRITE CYCLE TIMER
BCF STATUS,C ; CLEAR THE CARRY BIT
BTFSC DATA0,7 ; TEST THE MSB
BSF STATUS,C ; SET THE CARRY BIT
RLF DATA0,1 ; ROTATE DATAF
BCFPORTB,3; CLEAR THE HIGH VOLTAGE
CALL BUFFER; CALL THE BUFFER TIMER
DECF BIT,1; DECREMENT BIT, SKIP IF ZERO
BTFSS BIT,7 ; SKIP IF SET
GOTOWRITE0; GOTO WRITE0 IF BIT IS NOT EQUAL TO ZERO
RETLW 0
Delay12
NOP
microID™ 125
k
Hz Design Guide
DS51139A-page 146 1998 Microchip Technology Inc.
Delay11
GOTO Delay09
Delay09
GOTO Delay07
RS232On ;[1] Initialise RS-232
BCF _TMR2ON ; | Turn coil off
CALL RS232StopBit ; | Transmit stop bits
CALL RS232StopBit ; | |
CALL RS232StopBit ; | |
CALL RS232StopBit ; | |
CALL RS232StopBit ; | |
CALL RS232StopBit ; | |
CALL RS232StopBit ; | |
CALL RS232StopBit ; | |
CALL RS232StopBit ; | |
CALL RS232StopBit ; | |
RETLW h’00’ ; | return
RS232WaitForever ;[1] ~9600 baud
BigWaitL1 ; | {
CLRWDT ;!|
BTFSS _RS232IN ; | if (_RS232IN==#0)
GOTO RS232RxL1Done ; | { goto RS232RxL1Done }
NOP ;!|
GOTO BigWaitL1 ; | } until (0)
RS232Rx ;[1] ~9600 baud
MOVLW d’16’ ; | Set timeout of ~2.9s
MOVWF TimerHi ; | |
CLRF TimerMid ; | |
CLRF TimerLo ; | |
RS232RxL1 ; | {
CLRWDT ;!|
BTFSS _RS232IN ; | if (_RS232IN==#0)
GOTO RS232RxL1Done ; | { goto RS232RxL1Done }
DECFSZ TimerLo,f ; | }
GOTO RS232RxL1 ; | |
DECFSZ TimerMid,f ; | |
GOTO RS232RxL1 ; | |
DECFSZ TimerHi,f ; | |
GOTO RS232RxL1 ; | |
BSF _CARRY ; | return with error
RETLW h’00’ ; | |
; |
RS232RxL1Done ; |% 3 to (+6, +8, +10) - say 10us
; |% 10-104=-94
MOVLW d’90’ ;!|
CALL DelayW12 ;!|% 9
CLRF BitCtr ; | BitCtr=#8
BSF BitCtr,3 ; | |
RS232RxLoop ; | {% 11
MOVLW d’181’ ;!|
CALL DelayW12 ;!| % 205
CLRF BO3 ; | BO3,1=_RS232IN
BTFSC _RS232IN ; | |
INCF BO3,f ; | |% 208
BTFSC _RS232IN ; | |% 1
INCF BO3,f ; | |
BTFSC _RS232IN ; | |
INCF BO3,f ; | |% 4
RRF RxByte,f ; | RR RxByte
BCF RxByte,7 ; | RxByte,7=BO3,1
BTFSC BO3,1 ; | |
BSF RxByte,7 ; | |% 8
DECFSZ BitCtr,f ; | DEC BitCtr
1998 Microchip Technology Inc. DS51139A-page 147
microID™ 125
k
Hz Design Guide
GOTO RS232RxLoop ; | } until (BitCtr==#0)
BCF _CARRY ; | return with no error
RETLW h’00’ ; | |
RS232TxW ;[1] Transmit W on RS232 at ~9600 baud
MOVWF TxByte ; | TxByte=W
CALL RS232StopBit ; | stop bit
CLRF BitCtr ; | BitCtr=#8
BSF BitCtr,3 ; | |
BCF _RS232OUT ; | Start bit
MOVLW d’191’ ; | |
CALL DelayW12 ; | |
RS232TxLoop ; | {% 205
BTFSS TxByte,0 ; | _RS232OUT=TxByte,0
BCF _RS232OUT ; | |% 207
BTFSC TxByte,0 ; | |% 208
BSF _RS232OUT ; | |% 1
RRF TxByte,f ; | RR TxByte
MOVLW d’187’ ;!|
CALL DelayW12 ;!| % 202
DECFSZ BitCtr,f ; | DEC BitCtr
GOTO RS232TxLoop ; | } until (BitCtr==#0)
GOTO RS232TxJ1 ; |
RS232TxJ1 ; |
NOP ; |% 207
BSF _RS232OUT ; | Stop bit
RETLW h’00’ ; | return
end
microID™ 125
k
Hz Design Guide
DS51139A-page 148 1998 Microchip Technology Inc.
NOTES:
1998 Microchip Technology Inc. DS51139A-page 149
microID™ 125
k
Hz Design Guide
NOTES:
microID™ 125
k
Hz Design Guide
DS51139A-page 150 1998 Microchip Technology Inc.
NOTES:
1998 Microchip Technology Inc. DS51139A-page 151
microID™ 125
k
Hz Design Guide
NOTES:
Information cont ai ned in this publi cation reg ardi ng device app l ications and the l i ke is intended for suggestion onl y and may be superseded by u pdat es. No representa tion or war ran ty is given and no liability is assumed
by Microchip Technology Incorpora ted with respec t to the accurac y or use of such informa tion, or infringe ment of patent s or other intel lectual proper ty rights aris ing from such use or othe rwise. Use of Mic rochip’ s products
as critical c om ponents in l ife support sys te m s is not authori zed except wit h express written appro val by Microchip. No licens es are co nve yed, implicit ly or otherwise, under any in tellectual property rights. The Microchip
logo and name are registered trademarks of Microchip Technology Inc . in the U.S.A. and other countries. A l l rig hts reserved. All other trademarks men tioned herein are the property of their res pective comp ani es .
1999 Microchip Technology Inc.
All rights reserved. © 1999 Microchip Technology Incorporated. Printed in the USA. 11/99 Printed on recycled paper.
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