HT CM400
HITAG™ Core Module Hardware
November 1996Product Specification
Revision 2.0
Core Module HT CM400 Rev.: 2.0 November 1996
Htcm400.doc/HS Page 2 of 31
Table of Contents
1. Introduction 5
2. System Overview 7
2.1. Transponders 7
2.2. Host 7
2.3. I/O - Functions 7
2.4. Connecting the Antenna 8
2.5. HITAG - Long Range Reader Module 8
2.6. Behaviour with Several Transponders 8
3. Specifications 9
3.1. Electrical Specifications 9
3.1.1. Power Supply and Supply Ripple 9
3.1.2. Modulation 9
3.1.2.1. Read/Write Device ⇒ Transponder 9
3.1.2.2. Transponder ⇒ Read/Write Device 9
3.1.3. Interfaces 9
3.1.4. Metallic Environment, Interferences 10
3.1.5. Distance between Two Antennas 10
3.1.6. Temperature Range 10
3.2. Mechanical Specifications 10
3.2.1. Dimensions 10
3.2.2. Mounting the Module 11
3.2.3. Pin Assignment 11
3.2.4. Pin Function Description 13
4. Description of the Core Module Functions 14
4.1. Block Diagram 14
4.1.1. EEPROM 14
4.1.2. Micro Controller 14
4.1.2.1. Interface: Micro Controller - HITAG Long Range Board 15
4.1.2.2. Interface: Micro Controller - HOST 15
4.1.3. Transmitter and Receiver 15
4.1.4. Antenna 15
5. Postal Approval 16
5.1. Filtering of Power Supply 17
5.2. Filtering of Antenna Circuit 17
5.3. ESD Protection 17
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6. Connection of the HITAG Core Module in order to build a proximity read/write device 18
6.1. Power Supply 18
6.2. Interface Driver 18
6.3. I / O Functions 19
6.4. Instructions for Building HITAG Proximity Antennas 19
6.4.1. Basics 19
6.4.2. Antenna Coil 20
6.4.3. Measuring the Inductance 21
6.4.4. Antenna Cable Length 21
6.4.5. Antenna Tuning 21
6.4.6. Determining the Serial Resistance of the Antenna 22
6.4.7. Checking the Antenna Voltage ÛL22
6.4.8. Procedure for Practical Antenna Design 23
6.4.9. Reference Antennas 25
6.5. Possible Sources of Errors by Connecting the HITAG Core Module 26
7. Security Considerations 27
7.1. Operating Security 27
7.1.1. Anticollision Mode 27
7.1.2. Monitoring the Supply Voltage 27
7.1.3. Antenna Rupture, Antenna Short Circuit 27
7.2. Data Reliability 28
7.2.1. CRC of a Data Stream b etween Reader Modul e and Tran sponder 28
7.2.2. Checking User Data 28
7.3. Data Privacy 28
8. Ordering Information 30
Author : Ulrich Brändle
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Definitions
Data sheet status
Objective specification This data sheet contains target or goal specifications for product development.
P re li mi n a ry spe cif ica tion This data sheet c ontai ns pr el im i nar y data; s upplem entar y data m ay be
publi shed l ater .
Produc t speci ficati on This data sheet c ontai ns final pr oduc t spec ificati ons .
Limiting values
Lim iti ng v alues giv en ar e i n accor danc e wi th the Abs olute Maxim um R ating Sy stem ( IEC 134).
Stress above one or m or e of the lim i ti ng val ues m ay caus e perm anent dam age to the dev ic e.
These ar e s tr ess rati ngs only and oper ation of the devic e at these or at any other condi tions
above those gi ven i n the C har acter i sti cs sec ti on of the specificati on i s not i m pli ed. Ex posur e to
li mi ti ng v alues for extended per iods m ay affect dev ic e r eli ability.
Application information
Where applic ati on inform ati on is giv en, i t is advi s ory and does not form par t of the specificati on.
Life support applications
These products are not designed for use in life support appliances, devices, or systems where
malfunction of these products can reasonably be expected to result in personal injury. Philips
Semiconductors customers using or selling these products for use in such applications do so on
the ir o w n r is k a nd a g r ee to fu lly inde mnify Philip s Se mic ondu c tor s for a ny d ama g e s r esulting from
such im proper use or sale.
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1. Introduction
- is the name o f one of the universal and powerful product lines of our 125 kHz family.
The contact less read/write syst em t hat wo rks with passive transponders is suitable for vario us ap-
plicatio ns. Inductive co upling helps yo u to achieve operat ing distances up to 1000 mm and t he use
of cryptography guarantees highest data security.
Anticollision Mode, which is used only in long range operation, allows you to handle several
t ransponders t hat ar e wit hin the co mmunicat io n field o f t he ant enna at t he same t ime, t hus achiev-
ing highest operating security and permitting to handle several data transfers quickly and simulta-
neously. In this context anticollision becomes an essential element of applications such as ski-
ticketing and long range access control. With applications of that type it will always happen that
several transponders arrive in the communication field of the antenna at the same time.
Nevertheless, the proximity application also prevents any type of malfunction even if several
transponders arrive in the communication field of the antenna at the same time.
The HITAG product family is used both in the proximity area (operating range up to about
200 mm) and in the long range area (operating range up to about 1000 mm). In both cases the
HITAG Core Module forms the central part as illustrated by the block diagram below:
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The HITAG Core Module provides you with a universal, cost-effective, and small module.
The use of modular architecture guarantees versatile usability and easy integration into bigger
systems.
The HITAG Core Module enables communication with the transponders of the 125 kHz family,
i.e. Philips Semiconductors’ HITAG 1 and HITAG 2, PIT (PCF793x) and µEM (H400x)
transponders which underlines the particular universality of the module.
Easy integration and application of the HITAG Core Module is due to:
• small size
• uncomplicated interfaces
Based on the Core Module delivered by Philips Semiconductors and using only a few additional
components, every client can build his individually designed Proximity Reader without difficulty.
Moreover, you can obtain an electronic unit of the Long Range Reader (with an additional high
frequency component) from Philips Semiconductors, if long range applications are required.
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2. System Overview
The HITAG Cor e Module is a compact module used in read/write devices for t he 125 kHz family.
Wit h only a few external co mpo nents (antenna coupling net work, interface driver, volt age deco u-
pling) you can use the HITAG Core Module as the central part of a HITAG Proximity Reader
Module:
*) not used in proximity applications
2.1. Transponders
The HITAG Core Module integrated into the read/write device can communicate with Philips
Semiconductors’ HITAG 1 and HITAG 2 transponders as well as with the µEM (H400x)
transponders and the Philips PCF793x family (PIT). You use software commands to switch the
device from being used as read/write device for HITAG transponders to a read device for
µEM (H400x) transponders or a read/write device for the PCF793x and the other way round.
2.2. Host
The co nnectio n to t he ho st ( e.g. : µC o r PC) is a serial int erface o n CMOS level for dat a t ransmis-
sions over shor ter distances. You can connect an RS232 as well as an RS422 inter face comp onent.
If yo u use an additio nal pin of the HITAG Core Module (Pin 1, TXDEN) as control pin, you can
realise an RS485 interface.
2.3. I/O - Functions
The I/O lines form the connection to pot ential keys and LEDs; t wo lines are wired as inputs, two
as outputs.
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2.4. Connecting the Antenna
Connect an antenna as shown in the following illustration:
The resistor R1 has to be used if the antenna voltage is too high (see Chapter 6.4.7.). With the
capacity C the antenna tuning is done, R2 has only to be used for antenna cable lengths of more
than 500 mm and is used for damping.
For more details concerning the design of HITAG Proximity antennas see Chapter 6.4.
2.5. HITAG - Long Range Reader Module
The HITAG Long Range Reader Module supplied by Philips Semiconductors uses some of the
module pins as interface to an additional high frequency and Digital Signal Processor (DSP) part.
2.6. Behaviour with Several Transponders
If several HITAG transponders arrive simultaneously within the communication field of the an-
tenna of a HITAG Proximity Reader Module, the "stronger" transponder (the nearer one) takes
o ver or - under special circumstances - no communication takes place. If the tr anspo nders ar r ive in
t he field one aft er the ot her, co mmunicat ion is est ablished wit h the first o ne, all o ther t ranspo nders
are ignored.
Nevertheless it is possible to mute transponders, so that several HITAG transponders can be ac-
cessed sequentially.
T his ens u r es t hat no t w o ( o r se ve r al) H I T AG t r ans p o nd e rs w ill ev er be pr o c es se d ( abo v e all w r it -
ten to!) accidentally at the same time.
If a HITAG Long Range Reader Module is used, Anticollision Mode is applied, which makes it
possible to read and write all the HITAG 1 transponders (theoretical up to 232) within the com-
municat io n field of the antenna simult ano usly. Because o f t he mutual influence of the t ransponder
coils - they detune each other if there are too many too close to each other - the number of the
transponders that can be operated simultaneously is limited.
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3. Specifications
3.1. Electrical Specifications
3.1.1. Power Supply and Supply Ripple
Power Su
pp
l
y
Su
pp
l
y
Current Power Consum
p
tion
5 VDC ± 5 % 100 mA max. 0.5 W
With the power supply filter described in chapter 5.1 the power supply ripple must be within the
following values:
frequency of ripple [kHz] maximum ripple amplitude [mVss]
0 ≤ f < 10 5
10 ≤ f < 20 25
20 ≤ f 40
3.1.2. Modulation
3.1.2.1. Read/Write Device ⇒ Transponder
Type of Modulation Modulation Ratio
amplitude shift keying (ASK) 100 %
That means the carrier is periodically blanked completely, the information is located in the inter-
vals between the pauses.
3.1.2.2. Transponder ⇒ Read/Write Device
Type of Modulation Modulation Ratio
amplitude shift keying (ASK) depending on the distance between
transponder and read/write device
3.1.3. Interfaces
Inter facing to the host is done on CMOS level. You can connect an RS232 int er face component or
an RS 422 inter face dr iver, but yo u can also implement an RS485 int erface using a contr o l pin (Pin
1, TXDEN). For the pin assignment please see Chapter 3.2.3.
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3.1.4. Metallic Environment, Interferences
The communication range is impaired by metallic environment and electromagnetic interferences
(e.g.: monitors, keyboards). Therefore, you should keep a distance of at least the antenna´s di-
ameter to metallic surfaces o r lo o ps as well as t o elect ro magnet ic int erferences. I f t his is not po ssi-
ble, you have to take preventive measures such as using ferrites for transponders and antennas or
shielding for antennas.
3.1.5. Distance between Two Antennas
In o rder t o be able t o o per ate t wo systems side by side witho ut negat ive influence o n co mmunica-
tion ranges, you must place the antennas at a minimum distance of four times the antenna diame-
ter. If you place them at a closer distance be sure to use suitable shielding or synchronisation.
3.1.6. Temperature Range
-25° C to +85° C (operating)
-40° C to +85° C (storage)
3.2. Mechanical Specifications
The module consists of the printed circuit board and one 14- and one 13-pole pin connector that
protrudes from the PCB.
3.2.1. Dimensions
The outer dimensions of the PCB are: 86 x 40 x 7 mm .
The module including the pin connectors is about 18 mm high.
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3.2.2. Mounting the Module
You can mount the module onto a base printed circuit board by soldering or plugging.
3.2.3. Pin Assignment
T h e follow in g illu s tr a tion s how s th e mod u le with its p in c onn e c tor s a n d p in n u mbe rin g (s e e n from
below the module, i.e. pins protruding):
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The following table shows the pin assignment of the pin connectors:
Pin Number Pin Name Type Function
1 TXDEN Ocontrol pin providing con-
nection to an RS485 inter-
face
2 RXLOW_DSP I
3 RXHIGH_DSP I
4 RXCOL_DSP Iinterface to the HITAG Long
5TXµPL_DSP ORange board
6 SCLK_DSP I
7 SFFT_DSP O
8 IC internally connected
9 ACNMAN_DSP Ointerface to the HITAG
10 HINMIRO_DSP OLong Range board
11 RXD Iserial
12 TXD Ointerface
13 IC internally
14 IC connected
15 OUT1 O
16 OUT2 OI/O pins
17 IN1 I
18 IN2 I
19 DVDD PWR digital voltage
20 DGND PWR supply (5 V)
21 NC not connected
22 AVDD PWR analog voltage
23 AGND PWR supply (5 V, GND)
24 NRESET Oreset output
25 NC not connected
26 TX1 Oantenna
27 RX Iinterface
I input pin
O output pin
PWR power supply pin
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3.2.4. Pin Function Description
Pin 1, TXDEN: This pin is used as control pin if you use an RS485 interface.
Pin 2, RXLOW_DSP: *)
Pin 3, RXHIGH_DSP: *)
Pin 4, RXCOL_DSP: *)
Pin 5, TXµPL_DSP: *)
Pin 6, SCLK_DSP: *)
Pin 7, SFFT_DSP: *)
Pin 8, IC: internally connected, this pin must not be connected
Pin 9, ACNMAN_DSP: *)
Pin 10, HINMIRO_DSP: *)
Pin 11, RXD: signal to the serial interface from the host
Pin 12, TXD: signal from the serial interface to the host
Pin 13, IC: internally connected, this pin must not be connected
Pin 14, IC: internally connected, this pin must not be connected
Pin 15, OUT1: output pin of the µC for controlling e. g. a LED (connection of e. g.
a BS170 or BSS123 as driver)
Pin 16, OUT2: output pin of the µC for controlling e. g. a LED (connection of e. g.
a BS170 or BSS123 as driver)
Pin 17, IN1: input for possible switch (must be active low, maximum input volt-
age: 5 V). Internal pull-up resistores are provided.
Pin 18, IN2: input for possible switch (must be active low, maximum input volt-
age: 5 V). Internal pull-up resistores are provided.
Pin 19, DVDD: digital power supply (5 V)
Pin 20, DGND: digital power supply (GND)
Pin 21, NC: not connected
Pin 22, AVDD: analog power supply (5 V)
Pin 23, AGND: analog ground
Pin 24, NRESET: This OC - signal coming from the power-on reset circuit can be used
as reset signal. Typ. 10 mA SINK, min. 2 mA SINK.
Pin 25, NC: not connected
Pin 26, TX1: antenna input signal
Pin 27, RX: antenna output signal
*) interface to the HITAG Long Range board.
Not used pins stay unconnected.
Note: Input, output current on any single of pins 1, 11, 12, 15, 16, 17 and 18: 1.5 mA;
Maximum capacitive loading on each single of these pins: 80 pF.
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4. Description of the Core Module Functions
4.1. Block Diagram
L
Note: R2 has only to be used for antenna cable lengths of more than 500 mm.
4.1.1. EEPROM
The EEPROM is used to store non-volatile data such as personalization data, keys, passwords,
configurations and status information.
4.1.2. Micro Controller
The micro co ntr oller processes the prot oco l for t he co mmunicatio n between the transponders and
the read/write unit. The interface signals are converted so that a HITAG 1, HITAG 2, Philips
PCF793x or µE M (H400x) transponder is able t o pro cess them and the outgoing signals from t he
transponder are converted into interface-compatible signals.
The second essential micro controller function is its control function. The micro controller acti-
vates and deactivates the transmitter, switches the receiver from HITAG to Philips PCF793x or
µEM (H400x) transponder reception and back and selects the EEPROM.
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4.1.2.1. Interface: Micro Controller - HITAG Long Range Board
This interface is not wired with proximity applications (leave pins open).
4.1.2.2. Interface: Micro Controller - HOST
The device communicates with the ho st (processor, PC, ...) via a serial interface using a baud rate
of 9600 baud. Data transfer details are: 1 start bit, 8 data bits, 1 stop bit and no parity bit, the
Least Significant Bit is sent first.
An RS 232 interface device can be co nnected to the HITAG Co r e Mo dule. Optionally an RS422 or
an RS485 device is possible.
4.1.3. Transmitter and Receiver
The transmitter receives data from the micro controller and modulates the carrier.
The receiver demo dulates the received data and passes t hem o n to the micro co ntro ller for furt her
processing.
4.1.4. Antenna
To the design of HITAG Proximity Antennas see Chapter 6.4.
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5. Postal Approval
The postal approval can only be granted for final products, not just for components like the
HITAG Core Module. But the Core Module is designed in a way that it is possible to get the
postal approval for a device including the HITAG Core Module, if you follow the design instruc-
tions given by Philips Semiconductors.
Electromagnetic emission comply wit h the guidelines in FTZ 17 TR 2100 and ETS 300 683, elec-
tromagnetic immunity complies with the guidelines in ETS 300 683.
Following circuit diagram shows the basic configuration using the HITAG Core Module used to
comply with the standards and some additional circuits which are recommended.
Fig. 1
Common mode filtering
The design consists of a virtual ground layer (drawn grey in the schematic above). All entering
wires are blocked by 1nF ceramic capacitors to this layer to prevent common mode disturbances
from entering the fo llowing circuit s. The virt ual gro und layer is flo ating, it is not connected t o t he
ground itself.
A recommended metal housing that covers the HITAG Core Module would also be connected to
this floating layer.
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5.1. Filtering of Power Supply
The transmitter of the HITAG Core Module is supplied via AVDD and GND. Disturbances on
these supply pins are amplified and may reduce the performance of the system. For that reason
especially the analog supply (AVDD) must be filtered in addition to the commom mode filtering
described in Fig. 1.
On the other hand the spurious emissions at the supply connections caused by the digital parts of
the module must be limited (DVDD).
A supressor diode protects the core module from ESD to the power supply line.
Fig. 2
Power supply filtering
5.2. Filtering of Antenna Circuit
In case of using an external antenna with shielded antenna cable no additional filtering should be
necessary. I n case o f heavy distur bed environment an additio nal filter circuit is reco mmended when
using external antennas.
Using this filter will reduce the reading performance about 20% !
Fig. 3
Filtering of antenna circuit
5.3. ESD Protection
All I/Os should be protected by common circuits consisting of series resistance and suppresser
diode.
The transmitter output is already protected by a series resistor and internal diodes of the driving
FET´s. To pro tect the receiver input a 40V bi-directio nal suppresser dio de at the antenna connec-
tion is recommended.
If the additional filter shown in Fig. 3 is used, no more protection circuits are needed.
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6. Connection of the HITAG Core Module in order
to build a proximity read/write device
You need only a few external components to make the HITAG Core Module into a proximity
read/write device:
Filter
On/Off Switch (optional)
if needed
if needed
6.1. Power Supply
Yo u have to supply the HITAG Core Mo dule with 5 VDC ± 5 % and it is abso lut ely necessary t o
use low resistance (< 0.7 Ω) power supply. Voltage regulation is required and we recommend
separate supply for analog and digital parts.
See also chapter 3.1.1 for power supply ripple.
6.2. Interface Driver
Signal t ransmissio n for direct connection to the host can be done over the serial CMOS int erface.
For sho rt dist ances t he tr ansmissio n can be do ne over an RS232 int erface, lo nger distances requir e
integration of an RS485 or RS422 interface component. If you use an RS485 interface, Pin 1
(TXDEN) is used as control pin.
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6.3. I / O Functions
If necessary you can connect these inputs and outputs to drivers for LEDs and keys.
6.4. Instructions for Building HITAG Proximity Antennas
The antenna is an important part in the data transmission process between read/write device and
t ransponder. Therefor e, yo u should be particular ly careful when implementing the antenna in or der
to achieve optimum results.
An essential aspect in dimensioning HITAG proximity antennas is the ratio between the antenna
diameter and the diameter of the transponder coil. This ratio should be within the limit values 3
and 1. If the ratio is too big or too small read/write distances can decrease and difficulties during
data transmission may occur.
For applications in which the transponders are to be only read, you can also use antennas that di-
verge from above mentioned instruction.
6.4.1. Basics
The fo llowing block diagram shows the general architect ure of a HITAG Proximit y antenna and
its connection to the HITAG Core Module.
R
f = 125 kHz
AGND
HITAG Core Module Antenna
with Antenna Equivalent Circuit
LL
RR
R
CC
ÎTX1
Rx
Û
Û
1
L
22
s
s
ss
out
When de veloping an anten na, it is importa nt to take into consideration th e re ad/write device limits,
i. e. maximum antenna current and maximum vo lt age at t he receiver input. With an o utput voltage
Ûout of about 2.5 Vp the following limits apply to the HITAG Core Module:
maximum antenna current: 100 mAp
maximum input voltage (at the receiver (ÛL)):32 Vp
The resistance R1 (2 2 Ohm) in the blo ck diagr am is used as c urr ent limit er. It pr ot ect s t he o ut pu t
st age in t he event o f a possible sho rt cir cuit in the ant enna and is already integrat ed in t he HI TAG
Core Module. R2 (approx. 600 ... 1000 Ω) has only to be used for antenna cable lengths of more
than 50 cm.
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6.4.2. Antenna Coil
The inductance of the coil should be between 350 and 500 µH.
The antenna quality factor should be approximately Q = 40.
Q2fL
RS
=⋅⋅⋅π
Is the Q factor too high it must be reduced with an additional r esistor. It is the aim not t o need this
additional resistor but use a lower wire diameter of the coil.
The following formula describes the approximate calculation of the number of windings for a de-
sired inductance and antenna geometry:
L2aln
a
DKN
1.9
=⋅⋅ −
⋅
The abbreviations read as follows:
L ... desired inductance [nH]
a ... antenna circumference [cm]
D ... wire diameter [cm]
N ... number of windings
K ... geometrical constant
circular antenna : K=1.01
square antenna : K=1.47
Note: The factor K is normally much smaller than a/D and can be therefore left out:
NL
2aln(a/D)
1.9
≈⋅⋅
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6.4.3. Measuring the Inductance
The inductance of t he coil designed following above listed inst ruct ions can be measured using the
following measuring set-up:
A sinus signal of 125 kHz is fed using a function generator. If you measure the current Î and the
antenna voltage Û L you can calculate the inductance according to the following formula:
LUI
L
=⋅
ω
ω = 2×p×f
6.4.4. Antenna Cable Length
For optimal performance the antenna cable length should not exceed 5 m.
6.4.5. Antenna Tuning
You have to tune the antenna in its final form wit h t he co nnecting cable. Yo u must not make any
changes to the antenna coil or the connecting cable after you finished tuning because mechanical
changes influence the electrical values and the antenna is detuned again.
A sinus signal of 125 kHz is fed to the antenna using a frequency generator. You measure the
voltages Û and ÛR with an oscilloscope. Then you change the frequency until Û and ÛR are in
phase. If the resonance frequency thus arrived at is too high, you have to increase CS, if it is t o o
low, you have to decrease CS.
The aim is to arrive at a resonance frequency of 125 kHz using CS.
The resonance frequency has to be in the range of 125kHz ± 4kHz.
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6.4.6. Determining the Serial Resistance of the Antenna
Use an oscilloscope to measure ÛA and ÛR at a frequency of 125 kHz.
You can calculate the serial resistance RS of the antenna with the following formula:
ÎÛ
RR
=3
ÞRÛ
Î
sA
=
6.4.7. Checking the Antenna Voltage ÛL
Before connecting the antenna to the read/write device as shown in the illustration below, you
must carry out a check calculatio n of t he input level of the read/writ e device according to the fo r-
mulas further down in order to prevent damage.
ÎÛ
RRR
out
se
=++
1()
Ûout ≈ 2.5 Vp Û
L = L ⋅ ω ⋅ Î ω = 2 π f (f = 125 kHz)
The maximum value fo r ÛL reads 32 Vp , safeguarding against damage to the input level of the
read/write device.
With ÛL < 32 Vp the resistance Re can be omitted
With ÛL > 32 Vp you have to calculate and insert Re according to the following formula:
RL Û
ÛRR
eout
Ls
=⋅⋅ − −
ω
max 1ÞRL R
es
≥⋅ ⋅ − −
ω
0 078 22,
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6.4.8. Procedure for Practical Antenna Design
The procedure ho w t o design a HITAG Pro ximity antenna is described in t he previo us chapters.
The main steps are the following:
1. The desired inductance for the antenna coil can be chosen in a range between 350 and
500 µH, e.g. L = 420 µH).
2. The number of windings N can be calculated with the following formula:
NL [nH ]
2 a ln(a / D) - K
1.9
=⋅⋅
for L = 420 µH:
N420 000
2aln(a/D) - K
1. 9
=⋅⋅ = 633
aln(a/D)
1.9 ⋅
Note: The factor K (see also Chapter 6.4.2.) normally is much smaller than a/D and can be
therefore left out.
3. Now the antenna can be built up with the desired dimensions (⇒ circumference a) with
the calculated number of turns.
Note: The antenna coil must not be changed afterwards because with the mechanical
dimensions the electrical specifications are changing too. That means the number of
turns, the shape, arrangement of the coil windings and antenna supply cable must be in
their final form.
Note: Metal influences the electrical characteristics of the antenna very much. That is why
all future tasks have to be done with the antenna in its final environment if metal will
be in the antenna´s neighbourhoud (distance of the metal < maximum antenna
diameter).
4. Measurement of the inductance L of the antenna is described in Chapter 6.4.3.
5. Determination of the serial capacitor CS is described in Chapter 6.4.5.
Note: The capacitance of the antenna supply cable can be measured or found out in the data
sheet of the cable (e.g. Cp = 180 pF/m).
6. Now the antenna has to be tuned according to Chapter 6.4.5.
The tuning is acceptable if the resonance frequency is within a range of 125kHz ± 4kHz.
7. The serial resistance RS of the antenna is the impedance of the tuned antenna and is an
ohmic resistance at the resonance frequency (f = 125 kHz). It can be calculated as shown
in Chapter 6.4.6.
Core Module HT CM400 Rev.: 2.0 November 1996
Htcm400.doc/HS Page 24 of 31
8. To get a satisfactory reading distance the quality factor of the antenna coil (for non-metal
environment) should be about Q = 40. The quality factor of a coil is calculated as
follows:
QL
R2fL
R
SS
=⋅=⋅⋅⋅ωπ
9. By knowing RS and the dropping resistor (R1 = 22 Ω) it is possible to calculate the
current Î and the antenna voltage ÛL.
It is very important to calculate the antenna voltage before connecting the antenna to the
HITAG Core Module to avoid damage. Is the calculated value of ÛL higher than
ÛL = 32 Vp a resistor Re has to be integrated to protect the module output circuit. The
resistor has to be placed as shown in Chapter 6.4.7.
10. After checking the antenna voltage as described in point 9. connect your antenna to the
HITAG Core Module and measure the read/write distances with your transponders.
If the read/write distances do not fulfill your expectations, the following points should be
considered:
•The size of the antenna and the size of the transponder have to be in a defined ratio
(between 3 and 1).
That means, if you increase the antenna over a certain size, the maximum read/write
distances will decrease by the use of the same transponder.
•The optimal shape of the antenna coil is a circle. The performance of a square shaped
coil is much better than that of a rectangular shaped coil (with the same
circumference).
•To get better read/write distances the quality factor of the antenna coil should be
increased, but it must not be higher than Q = 40. This can be reached by the following
measures:
- All conducting material has to be removed from the antenna environment.
- A thicker wire can be used for the coil.
- Ferrite can be placed behind the antenna coil to concentrate the field.
- Extension of the antenna area.
- There can be better results by trying another number of turns.
Attention: All these measures must not differ from the antenna design instructions of
Chapter 6.4.
Note: With additional dropping resistor R1 and resistor Re the quality factor of the whole
antenna system is about Q = 15.
November 1996 Rev.: 2.0 Core Module HT CM400
Page 25 of 31 Htcm400.doc/HS
6.4.9. Reference Antennas
Designing an antenna in the way described in this chapter you could use the following values:
·∅ 0.4 mm Cu - laqueur wire
· 35 turns
· Diameter of the turns (internal): 145 mm
· Tuning frequency: 125 kHz
· Tuning Capacity depending on: - length of the antenna cable
- exact way of winding
This antenna is best suitable for HITAG 1 and HITAG 2 cards. In this performance reading di-
stances of about 150 mm should be achieved.
A further antenna configuration:
·∅ 0.224 mm Cu - laqueur wire
· 52 turns
· Diameter of the turns (internal): 6 5 mm
· Tuning frequency: 125 kHz
· Tuning Capacity depending on: - length of the antenna cable
- exact way of winding
In this case cards and coins can be used and the following approximate communication distances
should be achieved:
read distance with HITAG 1 and HITAG 2 card: 120 mm
read distance with HITAG 1 and HITAG 2 coin: 65 mm
The third antenna configuration is the smallest one:
·∅ 0.224 mm Cu - laqueur wire
· 85 turns
· Diameter of the turns (internal): 3 5 mm
· Tuning frequency: 125 kHz
· Tuning Capacity depending on: - length of the antenna cable
- exact way of winding
Using this antenna coins and pills can be operated up to the following approximate distances:
read distance with HITAG 1 coin: 58 mm
read distance with HITAG 1 pill: 2 8 m m
All distances are given in free air at room temperature.
Specifications subject to change without notice.
Core Module HT CM400 Rev.: 2.0 November 1996
Htcm400.doc/HS Page 26 of 31
6.5. Possible Sources of Errors by Connecting the HITAG
Core Module
The fo llowing error list should be checked if any erro r (e.g. read/write dist ances that do not reach
the specified values) occurs:
•Power supply cable not mounted correctly.
•Bad filtering of the power supply.
Remedial measure: Filtering as described in Chapter 5.1.
•Power supply not in the specified range (U = 5 VDC ± 5 %).
•RS232 interface not connected correctly.
•Interference received by the HITAG Core Module because of the digital part of a
possible additional circuit board.
Remedial measure: Shielding of the additional circuit board.
•Interference received by the HITAG Core Module because of an external noise source.
Remedial measure: Housing of metal or shielding.
•Interference received by the antenna because of an external noise source (e.g. monitor,
keys).
Remedial measure: Removal of the antenna from the interfering area.
•Connecting cables of the antenna changed by mistake.
•Antenna is mounted in metal environment.
Remedial measure: Mount a non-metal space keeper between the antenna and the metal.
•Antenna is not designed following the design instructions of Chapter 6.4.
•Inductance of the antenna is too high.
•Quality factor of the antenna is too high (> 40).
•Antenna current is too high.
•Antenna voltage is too high.
November 1996 Rev.: 2.0 Core Module HT CM400
Page 27 of 31 Htcm400.doc/HS
7. Security Considerations
Developing the HITAG Core Module special consideration was given to aspects of security. The
following items represent the fundamental framework of the security concept:
• cryptography
• mutual authentication
• password verification and
• Cyclic Redundancy Check (CRC)
7.1. Operating Security
The following mechanisms ensure the operation security of the HITAG system.
7.1.1. Anticollision Mode
Ant ico llisio n Mo de in lo ng r ang e a pp lica tio ns per mits yo u t o pro cess se ver al H ITAG 1 tr ansp on-
ders simultaneously. Theoretically up to 232 transponders can be processed simultanously. In
pr ac tice this number is limit ed , because of the mutual influence of the transponders - they detune
each other, if there are too many too close to each other.
I n p r o ximit y a pp lica t ion s u sing H I T AG 1 o r HI T AG 2 t r ans p o nd e rs, o nly on e tr a ns p o nd e r is ha n-
dled even if there are several transponders within the communication field of the antenna. In this
case either no communication takes place or the "stronger" or closer transponder takes over.
By muting a selected transponder (HALT Mode) another transponder that is to be found in the
communication field of the antenna can be recognized.
7.1.2. Monitoring the Supply Voltage
Supply voltage is controlled by a watch dog circuit which triggers a system reset if the supply
voltage drops below 4.75 V or if the micro controller fails.
7.1.3. Antenna Rupture, Antenna Short Circuit
The HITAG Core Module does not get permanently damaged in case of an antenna rupture or a
brief antenna short circuit.
Core Module HT CM400 Rev.: 2.0 November 1996
Htcm400.doc/HS Page 28 of 31
7.2. Data Reliability
All the commands and data transferred from the HITAG Proximity Reader Module to the
transponder are secured by Cyclic Redundancy Check (CRC).
7.2.1. CRC of a Data Stream between Reader Module and Transponder
(This check is carried out in the transponder)
Every data stream sent (commands, addresses, user data) from the HITAG Proximity Reader
Module to the transponder is first checked for data errors by a transponder-integrated 8-bit CRC
generator and then executed. Normally the transponder responds to each data stream from the
HITAG Proximity Reader Module with an acknowledgement signal or with a data block. The
CRC is for med o ver co mmands and addresses o r the plain dat a resp ectively and in t he case of En-
crypted Mode it is also encrypted.
The generator polynomial of the transponder CRC generator reads:
u8 + u4 + u3 + u2 + 1 ............= 0x1D
and the CRC preassignment is: 0xFF
7.2.2. Checking User Data
(This check is carried out in the HITAG Proximity Reader Module)
Sec urit y o f t he dat a r ead fr om t he t ranspo nd er by t he HI TAG Pr oximit y Re ad er Mo du le r ema ins
with the user for reasons of flexibility. Therefore, you can choose flexible check sums and store
them in the EEPROM together with the data. You can protect sensitive data better than less sen-
sitive data, thus permitting optimised operation times.
Det ailed instr uctions how to use and calculate Cyclic Redu ndancy Check (CRC) are available in an
additional document.
November 1996 Rev.: 2.0 Core Module HT CM400
Page 29 of 31 Htcm400.doc/HS
7.3. Data Privacy
The use of cryptography (Stream Cypher), mutual authentication, and password verification pre-
vents monitoring and copying the data channel. Therefore, the area of the transponder that only
can be accessed enciphered is called “secret area“.
To make use of cryptography you need secret data: keys and logdata.
Keys are used to initialise the crypto block
and logdata are used for mutual authentication.
T he t r a ns po nd e r s a nd t h e H I T AG P r o ximity R ea de r Mo d u le a r e pr ov ide d w it h id e nt ic a l t r a ns po r t
keys and transport logdata so that you can start operating them right away.
The KeyInit Password is set t o 0x00000000, HITAG 1 Keys and Lo gdata are set to 0x00000000,
HITAG 2 Key is set to 0x4D494B524F4E, HIT AG 2 Passwor d T AG to 0xAA4854 and HI T AG 2
Password RWD to 0x4D494B52 by Philips Semiconductors (predefined transport values).
In order to offer our OEM clients high flexibility, the configuration of the transponder memory,
password, keys and logdata can be changed.
We st rict ly recommend t o rigorously rest rict these possibilities fo r the end customers (by setting
the configuration page to read only, setting password, keys and logdata to neither read nor write).
See also Software-Protocol Reader - Host.
Core Module HT CM400 Rev.: 2.0 November 1996
Htcm400.doc/HS Page 30 of 31
8. Ordering Information
Type Name Description Ordering Number
HT CM400/EAE HITAG Core Module 9352 339 00122
November 1996 Rev.: 2.0 Core Module HT CM400
Page 31 of 31 Htcm400.doc/HS
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