Features
•8-bit Microcontroller Compatible with MCS®51 Products
•Enhanced 8051 Architecture
– Single Clock Cycle per Byte Fetch
– Up to 20 MIPS Throughput at 20 MHz Clock Frequency
– Fully Static Operation: 0 Hz to 20 MHz
– On-chip 2-cycle Hardware Multiplier
– 128 x 8 Internal RAM
– 4-level Interrupt Priority
•Nonvolatile Program Memory
– 2K Bytes of In-System Programmable (ISP) Flash Memory
– Endurance: Minimum 10,000 Write/Erase Cycles
– Serial Interface for Program Downloading
– 32-byte Fast Page Programming Mode
– 64-byte User Signature Array
– 2-level Program Memory Lock for Software Security
•Peripheral Features
– Two 16-bit Enhanced Timer/Counters
– Two 8-bit PWM Outputs
– Enhanced UART with Automatic Address Recognition and Framing
Error Detection
– Enhanced Master/Slave SPI with Double-buffered Send/Receive
– Programmable Watchdog Timer with Software Reset
– Analog Comparator with Selectable Interrupt and Debouncing
– 8 General-purpose Interrupt Pins
•Special Microcontroller Features
– Two-wire On-chip Debug Interface
– Brown-out Detection and Power-on Reset with Power-off Flag
– Internal 8 MHz RC Oscillator
– Low Power Idle and Power-down Modes
– Interrupt Recovery from Power-down Mode
•I/O and Packages
– Up to 14 Programmable I/O Lines
– Configurable I/O with Quasi-bidirectional, Input, Push-pull Output, and
Open-drain Modes
– 5V Tolerant I/O
– 16-lead TSSOP, SOIC or PDIP
•Operating Conditions
– 2.4V to 5.5V VCC Voltage Range
–-40⋅C to 85°C Temperature Range
1. Description
The AT89LP216 is a low-power, high-performance CMOS 8-bit microcontroller with
2K bytes of In-System Programmable Flash memory. The device is manufactured
using Atmel®'s high-density nonvolatile memory technology and is compatible with the
industry-standard MCS-51 instruction set. The AT89LP216 is built around an
enhanced CPU core that can fetch a single byte from memory every clock cycle.
In the classic 8051 architecture, each fetch requires 6 clock cycles, forcing instruc-
tions to execute in 12, 24 or 48 clock cycles. In the AT89LP216 CPU, instructions
8-bit
Microcontroller
with 2K Bytes
Flash
AT89LP216
3621E–MICRO–11/10
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3621E–MICRO–11/10
AT89LP216
need only 1 to 4 clock cycles providing 6 to 12 times more throughput than the standard 8051.
Seventy percent of instructions need only as many clock cycles as they have bytes to execute,
and most of the remaining instructions require only one additional clock. The enhanced CPU
core is capable of 20 MIPS throughput whereas the classic 8051 CPU can deliver only 4 MIPS
at the same current consumption. Conversely, at the same throughput as the classic 8051, the
new CPU core runs at a much lower speed and thereby greatly reduces power consumption.
The AT89LP216 provides the following standard features: 2K bytes of In-System Programmable
Flash memory, 128 bytes of RAM, up to 14 I/O lines, two 16-bit timer/counters, two PWM out-
puts, a programmable watchdog timer, a full duplex serial port, a serial peripheral interface, an
internal 8 MHz RC oscillator, on-chip crystal oscillator, and a four-level, six-vector interrupt
system.
The two timer/counters in the AT89LP216 are enhanced with two new modes. Mode 0 can be
configured as a variable 9- to 16-bit timer/counter and Mode 1 can be configured as a 16-bit
auto-reload timer/counter. In addition, the timer/counters may independently drive a pulse width
modulation output.
The I/O ports of the AT89LP216 can be independently configured in one of four operating
modes. In quasi-bidirectional mode, the ports operate as in the classic 8051. In input mode, the
ports are tristated. Push-pull output mode provides full CMOS drivers and open-drain mode pro-
vides just a pull-down. In addition, all 8 pins of Port 1 can be configured to generate an interrupt
using the general-purpose interrupt interface. The I/O pins of the AT89LP216 tolerate voltages
higher than the device’s own power supply, up to 5.5V. When the device is supplied at 2.4V and
all I/O ports receive 5.5V, the total back flowing current in all I/Os is less than 100 µA.
2. Pin Configuration
2.1 16-lead PDIP/SOIC/TSSOP
1
2
3
4
5
6
7
8
16
15
14
13
12
11
10
9
(GPI5/MOSI) P1.5
(GPI7/SCK) P1.7
(GPI3/RST) P1.3
GND
(GPI2) P1.2
(RXD) P3.0
(T0) P3.4
(XTAL1/INT0) P3.2
P1.6 (MISO/GPI6)
P1.4 (SS/GPI4)
P1.1 (AIN1/GPI1)
P1.0 (AIN0/GPI0)
VCC
P3.1 (TXD)
P3.5 (T1)
P3.3 (INT1/XTAL2/CLKOUT)
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AT89LP216
3. Pin Description
Table 3-1. Pin Description
Pin Symbol Type Description
1P1.5
I/O
I/O
I
P1.5: User-configurable I/O Port 1 bit 5.
MOSI: SPI master-out/slave-in. When configured as master, this pin is an output. When configured as slave, this pin
is an input.
GPI5: General-purpose Interrupt input 5.
2P1.7
I/O
I/O
I
P1.7: User-configurable I/O Port 1 bit 7.
SCK: SPI Clock. When configured as master, this pin is an output. When configured as slave, this pin is an input.
GPI7: General-purpose Interrupt input 7.
3P1.3
I/O
I
I
I
P1.3: User-configurable I/O Port 1 bit 3 (if Reset Fuse is disabled).
RST: External Active-Low Reset input (if Reset Fuse is enabled, see Section 10.3 “External Reset” on page 15)
GPI3: General-purpose Interrupt input 3.
DCL: Serial Clock input for On-Chip Debug Interface when OCD is enabled.
4 GND I Ground
5P1.2
I/O
I
P1.2: User-configurable I/O Port 1 bit 2.
GPI2: General-purpose Interrupt input 2.
6P3.0
I/O
I
P3.0: User-configurable I/O Port 3 bit 0.
RXD: Serial Port Receiver Input.
7P3.4
I/O
I/O
P3.4: User-configurable I/O Port 3 bit 4.
T0: Timer/Counter 0 External Input or PWM Output.
8P3.2
I/O
I
I/O
P3.2: User-configurable I/O Port 3 bit 2.
XTAL1: Input to the inverting oscillator amplifier and internal clock generation circuits. It may be used as a port pin if
the internal RC oscillator is selected as the clock source.
DDA: Serial Data input/output for On-Chip Debug Interface when OCD is enabled and the internal RC oscillator is
selected as the clock source.
9P3.3
I/O
O
O
I/O
P3.3: User-configurable I/O Port 3 bit 3.
XTAL2: Output from inverting oscillator amplifier. It may be used as a port pin if the internal RC oscillator is selected
as the clock source.
CLKOUT: When the internal RC oscillator is selected as the clock source, may be used to output the internal clock
divided by 2.
DDA: Serial Data input/output for On-Chip Debug Interface when OCD is enabled and the external clock is selected
as the clock source.
10 P3.5 I/O
I/O
P3.5: User-configurable I/O Port 3 bit 5.
T1: Timer/Counter 1 External input or PWM output.
11 P3.1 I/O
O
P3.1: User-configurable I/O Port 3 bit 1.
TXD: Serial Port Transmitter Output.
12 VDD I Supply Voltage
13 P1.0
I/O
I
I
P1.0: User-configurable I/O Port 1 bit 0.
AIN0: Analog Comparator Positive input.
GPI0: General-purpose Interrupt input 0.
14 P1.1
I/O
I
I
P1.1: User-configurable I/O Port 1 bit 1.
AIN1: Analog Comparator Negative input.
GPI1: General-purpose Interrupt input 1
15 P1.4
I/O
I
I
P1.4: User-configurable I/O Port 1 bit 4.
SS: SPI slave select input.
GPI4: General-purpose Interrupt input 4.
16 P1.6
I/O
I/O
I
P1.6: User-configurable I/O Port 1 bit 6.
MISO: SPI master-in/slave-out. When configured as master, this pin is an input. When configured as slave, this pin
is an output.
GPI6: General-purpose Interrupt input 6.
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AT89LP216
4. Block Diagram
Figure 4-1. AT89LP216 Block Diagram
5. Comparison to Standard 8051
The AT89LP216 is part of a family of devices with enhanced features that are fully binary com-
patible with the MCS-51 instruction set. In addition, most SFR addresses, bit assignments, and
pin alternate functions are identical to Atmel’s existing standard 8051 products. However, due to
the high performance nature of the device, some system behaviors are different from those of
Atmel's standard 8051 products such as AT89S52 or AT89S2051. The differences from the
standard 8051 are outlined in the following paragraphs.
5.1 System Clock
The CPU clock frequency equals the external XTAL1 frequency. The oscillator is no longer
divided by 2 to provide the internal clock and x2 mode is not supported.
5.2 Instruction Execution with Single-cycle Fetch
The CPU fetches one code byte from memory every clock cycle instead of every six clock
cycles. This greatly increases the throughput of the CPU. As a consequence, the CPU no longer
executes instructions in 12 to 48 clock cycles. Each instruction executes in only 1 to 4 clock
cycles. See “Instruction Set Summary” on page 59 for more details.
Single Cycle
8051 CPU
2K Bytes
Flash
128 Bytes
RAM
Port 3
Configurable I/O
Port 1
Configurable I/O
UART
SPI
Timer 0
Timer 1
Analog
Comparator
Watchdog
Timer
On-Chip
RC Oscillator
General-purpose
Interrupt
Configurable
Oscillator
CPU Clock Crystal or
Resonator
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AT89LP216
5.3 Interrupt Handling
The interrupt controller polls the interrupt flags during the last clock cycle of any instruction. In
order for an interrupt to be serviced at the end of an instruction, its flag needs to have been
latched as active during the next to last clock cycle of the instruction, or in the last clock cycle of
the previous instruction if the current instruction executes in only a single clock cycle.
The external interrupt pins, INT0 and INT1, are sampled at every clock cycle instead of once
every 12 clock cycles. Coupled with the shorter instruction timing and faster interrupt response,
this leads to a higher maximum rate of incidence for the external interrupts.
5.4 Timer/Counters
By default the Timer/Counters is incremented at a rate of once per clock cycle. This compares to
once every 12 clocks in the standard 8051. A common prescaler is available to divide the time
base for all timers and reduce the increment rate. The TPS bits in the CLKREG SFR control the
prescaler (Table 9-2 on page 13). Setting TPS = 1011B will cause the timers to count once every
12 clocks.
The external Timer/Counter pins, T0 and T1, are sampled at every clock cycle instead of once
every 12 clock cycles. This increases the maximum rate at which the Counter modules may
function.
5.5 Serial Port
The baud rate of the UART in Mode 0 is 1/2 the clock frequency, compared to 1/12 the clock fre-
quency in the standard 8051; and output data is only stable around the rising edge of the serial
clock. In should also be noted that when using Timer 1 to generate the baud rate in Mode 1 or
Mode 3, the timer counts at the clock frequency and not at 1/12 the clock frequency. To maintain
the same baud rate in the AT89LP216 while running at the same frequency as a standard 8051,
the time-out period must be 12 times longer. Mode 1 of Timer 1 supports 16-bit auto-reload to
facilitate longer time-out periods for generating low baud rates.
5.6 Watchdog Timer
The Watchdog Timer in AT89LP216 counts at a rate of once per clock cycle. This compares to
once every 12 clocks in the standard 8051. A common prescaler is available to divide the time
base for all timers and reduce the counting rate.
5.7 I/O Ports
The I/O ports of the AT89LP216 may be configured in four different modes. By default all the I/O
ports revert to input-only (tristated) mode at power-up or reset. In the standard 8051, all ports
are weakly pulled high during power-up or reset. To enable 8051-like ports, the ports must be
put into quasi-bidirectional mode by clearing the P1M0 and P3M0 SFRs. The user can also con-
figure the ports to start in quasi-bidirectional mode by disabling the Tristate-Port User Fuse.
When this fuse is disabled, P1M0 and P3M0 will reset to 00h instead of FFh and the ports will be
weakly pulled high.
5.8 Reset
The RST pin of the AT89LP216 is active-low as compared with the active high reset in the stan-
dard 8051. In addition, the RST pin is sampled every clock cycle and must be held low for a
minimum of two clock cycles, instead of 24 clock cycles, to be recognized as a valid reset.
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AT89LP216
6. Memory Organization
The AT89LP216 uses a Harvard Architecture with separate address spaces for program and
data memory. The program memory has a regular linear address space with support for up to
64K bytes of directly addressable application code. The data memory has 128 bytes of internal
RAM and 128 bytes of Special Function Register I/O space. The AT89LP216 does not support
external data memory or external program memory.
6.1 Program Memory
The AT89LP216 contains 2K bytes of on-chip In-System Programmable Flash memory for pro-
gram storage. The Flash memory has an endurance of at least 10,000 write/erase cycles and a
minimum data retention time of 10 years. The reset and interrupt vectors are located within the
first 59 bytes of program memory (refer to Table 12-1 on page 19). Constant tables can be allo-
cated within the entire 2K program memory address space for access by the MOVC instruction.
The AT89LP216 does not support external program memory.
Figure 6-1. Program Memory Map
A map of the AT89LP216 program memory is shown in Figure 6-1. In addition to the 2K code
space from 0000h to 07FFh, the AT89LP216 also supports a 64-byte User Signature Array and
a 32-byte Atmel Signature Array that are accessible by the CPU in a read-only fashion. In order
to read from the signature arrays, the SIGEN bit in AUXR1 must be set. While SIGEN is one,
MOVC A,@A+DPTR will access the signature arrays. The User Signature Array is mapped to
addresses 0040h to 007Fh and the Atmel Signature Array is mapped to addresses 0000h to
001Fh. SIGEN must be cleared before using MOVC to access the code memory.
The Atmel Signature Array is initialized with the Device ID in the factory. The User Signature
Array is available for user identification codes or constant parameter data. Data stored in the sig-
nature array is not secure. Security bits will disable writes to the array; however, reads are
always allowed.
Table 6-1. AUXR1 – Auxiliary Register 1
AUXR1 = A2H Reset Value = XXXX 0XXXB
Not Bit Addressable
––––SIGEN–––
Bit76543210
Program Memory
0000
07FF
0000
001F
User Signature Array
0040
007F
Atmel Signature Array
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AT89LP216
6.2 Data Memory
The AT89LP216 contains 128 bytes of general SRAM data memory plus 128 bytes of I/O mem-
ory mapped into a single 8-bit address space. The 128 bytes of data memory may be accessed
through both direct and indirect addressing of the lower 128 byte addresses. The 128 bytes of
I/O memory reside in the upper 128 byte address space (Figure 6-2). The I/O memory can only
be accessed through direct addressing and contains the Special Function Registers (SFRs).
Indirect accesses to the upper 128 byte addresses will return invalid data. The lowest 32 bytes
of data memory are grouped into 4 banks of 8 registers each. The RS0 and RS1 bits (PSW.3
and PSW.4) select which register bank is in use. Instructions using register addressing will only
access the currently specified bank. The AT89LP216 does not support external data memory.
Figure 6-2. Data Memory Map
FFH
UPPER
128
80H
7F H
LOWER
128
0
Accessible
By Direct
Addressing
Only
Accessible
By Direct
and Indirect
Addressing
Only
Special Function
Registers
Ports
Status and Control Bits
Timers
Registers
Stack Pointer
Accumulator
(Etc.)
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AT89LP216
7. Special Function Registers
A map of the on-chip memory area called the Special Function Register (SFR) space is shown in
Table 7-1.
Note that not all of the addresses are occupied, and unoccupied addresses may not be imple-
mented on the chip. Read accesses to these addresses will in general return random data, and
write accesses will have an indeterminate effect. User software should not write to these unlisted
locations, since they may be used in future products to invoke new features.
Notes: 1. All SFRs in the left-most column are bit-addressable.
2. Reset value is xx11 1111B when Tristate-Port Fuse is enabled and xx00 0000B when disabled.
Table 7-1. AT89LP216 SFR Map and Reset Values
89ABCDEF
0F8H 0FFH
0F0H B
0000 0000 0F7H
0E8H SPSR
000x x000
SPCR
0000 0000
SPDR
xxxx xxxx 0EFH
0E0H ACC
0000 0000 0E7H
0D8H 0DFH
0D0H PSW
0000 0000 0D7H
0C8H 0CFH
0C0H P1M0(2) P1M1
xx00 0000 P3M0(2) P3M1
xx00 0000 0C7H
0B8H IP
x000 0000
SADEN
0000 0000 0BFH
0B0H P3
xx11 1111
IPH
x000 0000 0B7H
0A8H IE
0000 0000
SADDR
0000 0000 0AFH
0A0H AUXR1
xxxx 0xxx
WDTRST
(write-only)
WDTCON
0000 x000 0A7H
98H SCON
0000 0000
SBUF
xxxx xxxx
GPMOD
0000 0000
GPLS
0000 0000
GPIEN
0000 0000
GPIF
0000 0000 9FH
90H P1
1111 1111
TCONB
0010 0100
RL0
0000 0000
RL1
0000 0000
RH0
0000 0000
RH1
0000 0000
ACSR
xx00 0000 97H
88H TCON
0000 0000
TMOD
0000 0000
TL0
0000 0000
TL1
0000 0000
TH0
0000 0000
TH1
0000 0000
CLKREG
0000 x000 8FH
80H SP
0000 0111
DPL
0000 0000
DPH
0000 0000
PCON
0000 0000 87H
01234567
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AT89LP216
8. Enhanced CPU
The AT89LP216 uses an enhanced 8051 CPU that runs at 6 to 12 times the speed of standard
8051 devices (or 3 to 6 times the speed of X2 8051 devices). The increase in performance is
due to two factors. First, the CPU fetches one instruction byte from the code memory every clock
cycle. Second, the CPU uses a simple two-stage pipeline to fetch and execute instructions in
parallel. This basic pipelining concept allows the CPU to obtain up to 1 MIPS per MHz. A simple
example is shown in Figure 8-1.
The MCS-51 instruction set allows for instructions of variable length from 1 to 3 bytes. In a sin-
gle-clock-per-byte-fetch system this means each instruction takes at least as many clocks as it
has bytes to execute. The majority of instructions in the AT89LP216 follow this rule: the instruc-
tion execution time in clock cycles equals the number of bytes per instruction with a
few exceptions. Branches and Calls require an additional cycle to compute the target address
and some other complex instructions require multiple cycles. See “Instruction Set Summary” on
page 59 for more detailed information on individual instructions. Figures 8-2 and 8-3 show
examples of 1- and 2-byte instructions.
Figure 8-1. Parallel Instruction Fetches and Executions
Figure 8-2. Single-cycle ALU Operation (Example: INC R0)
System Clock
nth Instruction
(n+1)th Instruction
Fetch Execute
Fetch Execute
Fetch
TnTn+1 Tn+2
(n+2)th Instruction
System Clock
Total Execution Time
Register Operand Fetch
T1T2T3
ALU Operation Execute
Result Write Back
Fetch Next Instruction
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AT89LP216
Figure 8-3. Two-cycle ALU Operation (Example: ADD A, #Data)
8.1 Restrictions on Certain Instructions
The AT89LP216 is an economical and cost-effective member of Atmel’s growing family of micro-
controllers. It contains 2K bytes of Flash program memory. It is fully compatible with the MCS-51
architecture, and can be programmed using the MCS-51 instruction set. However, there are a
few considerations one must keep in mind when utilizing certain instructions to program this
device. All the instructions related to jumping or branching should be restricted such that the
destination address falls within the physical program memory space of the device, which is 2K
for the AT89LP216. This should be the responsibility of the software programmer. For example,
LJMP 7E0H would be a valid instruction, whereas LJMP 900H would not.
8.1.1 Branching Instructions
The LCALL, LJMP, ACALL, AJMP, SJMP, and JMP @A+DPTR unconditional branching instruc-
tions will execute correctly as long as the programmer keeps in mind that the destination
branching address must fall within the physical boundaries of the program memory size (loca-
tions 000H to 7FFH for the AT89LP216). Violating the physical space limits may cause unknown
program behavior. With the CJNE [...], DJNZ [...], JB, JNB, JC, JNC, JBC, JZ, and JNZ condi-
tional branching instructions, the same previous rule applies. Again, violating the memory
boundaries may cause erratic execution. For applications involving interrupts the normal inter-
rupt service routine address locations of the 8051 family architecture have been preserved.
8.1.2 MOVX-related Instructions, Data Memory
The AT89LP216 contains 128 bytes of internal data memory. The RAM accesses to addresses
above 7FH will return invalid data. Furthermore, the stack depth is limited to 128 bytes, the
amount of available RAM. The Stack Pointer should not be allowed to point to locations above
7FH. External DATA memory access is not supported in this device, nor is external PROGRAM
memory execution. Therefore, no MOVX [...] instructions should be included in the program.
A typical 8051 assembler will still assemble instructions, even if they are written in violation of
the restrictions mentioned above. It is the responsibility of the user to know the physical features
and limitations of the device being used and to adjust the instructions used accordingly.
System Clock
Total Execution Time
Fetch Immediate Operand
T1T2T3
ALU Operation Execute
Result Write Back
Fetch Next Instruction
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AT89LP216
9. System Clock
The system clock is generated directly from one of three selectable clock sources. The three
sources are the on-chip crystal oscillator, external clock source, and internal RC oscillator. The
clock source is selected by the Clock Source User Fuses as shown in Table 9-1. No internal
clock division is used to generate the CPU clock from the system clock. See “User Configuration
Fuses” on page 71.
9.1 Crystal Oscillator
When enabled, the internal inverting oscillator amplifier is connected between XTAL1 and
XTAL2. Note that the internal structure of the device adds about 10 pF of capacitance to both
XTAL1 and XTAL2, so that in some cases an external capacitor may NOT be required. It is rec-
ommended that a resistor R1 be connected to XTAL1, instead of load capacitor C1, for improved
startup performance. The total capacitance on XTAL1 or XTAL2, including the external load
capacitor plus internal device load, board trace and crystal loadings, should not exceed 20 pF.
When using the crystal oscillator, P3.2 and P3.3 will have their inputs and outputs disabled.
When using the crystal oscillator, XTAL2 should not be used to drive a board-level clock without
a buffer
Figure 9-1. Crystal Oscillator Connections
Note: 1. C2 = 0–10 pF for Crystals
= 0–10 pF for Ceramic Resonators
R1 = 4–5 MΩ
Table 9-1. Clock Source Settings
Clock Source
Fuse 1
Clock Source
Fuse 0 Selected Clock Source
0 0 Crystal Oscillator
01Reserved
1 0 External Clock on XTAL1
1 1 Internal 8 MHz RC Oscillator
~10 pF
~10 pF
C2
R1
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AT89LP216
9.2 External Clock Source
The external clock option disables the oscillator amplifier and allows XTAL1 to be driven directly
by the clock source as shown in Figure 9-2. XTAL2 may be left unconnected, used as P3.3 I/O,
or configured to output a divided version of the system clock.
Figure 9-2. External Clock Drive Configuration
9.3 Internal RC Oscillator
The AT89LP216 has an internal RC oscillator tuned to 8.0 MHz ±1.0% at 5.0V and 25⋅C. When
enabled as the clock source, XTAL1 and XTAL2 may be used as P3.2 and P3.3, respectively.
The XTAL2 may also be configured to output a divided version of the system clock. The fre-
quency of the oscillator may be adjusted by changing the RC Adjust Fuses. (See “User
Configuration Fuses” on page 71.) A copy of the initial factory setting is stored at location 0007h
of the Atmel Signature.
9.4 System Clock Out
When the AT89LP216 is configured to use either an external clock or the internal RC oscillator,
a divided version of the system clock may be output on XTAL2 (P3.3). The Clock Out feature is
enabled by setting the COE bit in CLKREG. The two CDV bits determine the clock divide ratio.
For example, setting COE = “1” and CDIV = “00” when using the internal oscillator will result in a
4.0 MHz clock output on P3.3. P3.3 must be configured as an output in order to use the clock out
feature.
XTAL2 (P3.3)
XTAL1 (P3.2)
GND
NC, GPIO, or
CLKOUT
EXTERNAL
OSCILLATOR
SIGNAL
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AT89LP216
10. Reset
During reset, all I/O Registers are set to their initial values, the port pins are tristated, and the
program starts execution from the Reset Vector, 0000H. The AT89LP216 has five sources of
reset: power-on reset, brown-out reset, external reset, watchdog reset, and software reset.
10.1 Power-on Reset
A Power-on Reset (POR) is generated by an on-chip detection circuit. The detection level is
nominally 1.4V. The POR is activated whenever VCC is below the detection level. The POR cir-
cuit can be used to trigger the start-up reset or to detect a supply voltage failure in devices
without a brown-out detector. The POR circuit ensures that the device is reset from power-on. A
power-on sequence is shown in Figure 10-1. When VCC reaches the Power-on Reset threshold
voltage VPOR, an initialization sequence lasting tPOR is started. When the initialization sequence
completes, the start-up timer determines how long the device is kept in POR after VCC rise. The
POR signal is activated again, without any delay, when VCC falls below the POR threshold level.
A Power-on Reset (i.e. a cold reset) will set the POF flag in PCON. The internally generated
reset can be extended beyond the power-on period by holding the RST pin low longer than the
time-out.
Table 9-2. CLKREG – Clock Control Register
CLKREG = 8FH Reset Value = 0000 0000B
Not Bit Addressable
TPS3 TPS2 TPS1 TPS0 – CDV1 CDV0 COE
Bit76543210
Symbol Function
TPS3
TPS2
TPS1
TPS0
Timer Prescaler. The Timer Prescaler selects the time base for Timer 0, Timer 1 and the Watchdog Timer. The prescaler
is implemented as a 4-bit binary down counter. When the counter reaches zero it is reloaded with the value stored in the
TPS bits to give a division ratio between 1 and 16. By default the timers will count every clock cycles (TPS = 0000B). To
configure the timers to count at a standard 8051 rate of once every 12 clock cycles, TPS should be set to 1011B.
CDV1
CDV0
Clock Out Division. Determines the frequency of the clock output relative to the system clock.
CDIV1 CDIV0 Clock Out Frequency
00f/2
01f/4
10f/8
11f/16
COE Clock Out Enable. Set COE to output a divided version of the system clock on XTAL2 (P3.3). The internal RC oscillator
or external clock source must be selected in order to use this feature.
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AT89LP216
Figure 10-1. Power-on Reset Sequence (BOD Disabled)
If the Brown-out Detector (BOD) is also enabled, the start-up timer does not begin counting until
after VCC reaches the BOD threshold voltage VBOD as shown in Figure 10-2. However, if this
event occurs prior to the end of the initialization sequence, the timer must first wait for that
sequence to complete before counting.
Figure 10-2. Power-on Reset Sequence (BOD Enabled)
Note: tPOR is approximately 92 µs ± 5%.
The start-up timer delay is user configurable with the Start-up Time User Fuses and depends on
the clock source (Table 10-1). The start-up delay should be selected to provide enough settling
time for VCC and the selected clock source. The Start-Up Time fuses also control the length of
the start-up time after a Brown-out Reset or when waking up from Power-down during internally
timed mode.
VCC
RST
Time-out
tPOR + tSUT
tRHD
VPOR
Internal
Reset
RST
Internal
Reset
VRH
(RST Tied to VCC)
(RST Controlled Externally)
VPOR
VCC
RST
Time-out tPOR
tRHD
VPOR
Internal
Reset
RST
Internal
Reset
VRH
tSUT
VBOD
(RST Tied to VCC)
(RST Controlled Externally)
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10.2 Brown-out Reset
The AT89LP216 has an on-chip Brown-out Detection (BOD) circuit for monitoring the VCC level
during operation by comparing it to a fixed trigger level. The trigger level for the BOD is nomi-
nally 2.2V. The purpose of the BOD is to ensure that if VCC fails or dips while executing at speed,
the system will gracefully enter reset without the possibility of errors induced by incorrect execu-
tion. A BOD sequence is shown in Figure 10-3. When VCC decreases to a value below the
trigger level VBOD, the internal reset is immediately activated. When VCC increases above the
trigger level, the start-up timer releases the internal reset after the specified time-out period has
expired (Table 10-1). The Brown-out Detector must be enabled by setting the BOD Enable Fuse.
(See “User Configuration Fuses” on page 71.)
Figure 10-3. Brown-out Detector Reset
10.3 External Reset
The P1.3/RST pin can function as either an active-LOW reset input or as a digital general-pur-
pose I/O, P1.3. The Reset Pin Enable Fuse, when set to “1”, enables the external reset input
function on P1.3. (See “User Configuration Fuses” on page 71.) When cleared, P1.3 may be
used as an input or output pin. When configured as a reset input, the pin must be held low for at
least two clock cycles to trigger the internal reset.
Note: During a power-up sequence, the fuse selection is always overridden and therefore the pin will
always function as a reset input. An external circuit connected to this pin should not hold this
pin LOW during a power-on sequence as this will keep the device in reset until the pin tran-
sitions high. After the power-up delay, this input will function either as an external reset input or
as a digital input as defined by the fuse bit. Only a power-up reset will temporarily override the
selection defined by the reset fuse bit. Other sources of reset will not override the reset fuse bit.
P1.3/RST also serves as the In-System Programming (ISP) enable. ISP is enabled when the
external reset pin is held low. When the reset pin is disabled by the fuse, ISP may only be entered
by pulling P1.3 low during power-up.
Table 10-1. Start-up Timer Settings
SUT Fuse 1 SUT Fuse 0 Clock Source tSUT (± 5%)
00
Internal RC/External Clock 16 µs
Crystal Oscillator 1024 µs
01
Internal RC/External Clock 512 µs
Crystal Oscillator 2048 µs
10
Internal RC/External Clock 1024 µs
Crystal Oscillator 4096 µs
11
Internal RC/External Clock 4096 µs
Crystal Oscillator 16384 µs
VCC
Time-out
VPOR
Internal
Reset
tSUT
VBOD
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AT89LP216
10.4 Watchdog Reset
When the Watchdog times out, it will generate an internal reset pulse lasting 16 clock cycles.
Watchdog reset will also set the WDTOVF flag in WDTCON. To prevent a Watchdog reset, the
watchdog reset sequence 1EH/E1H must be written to WDTRST before the Watchdog times
out. See “Programmable Watchdog Timer” on page 57 for details on the operation of the
Watchdog.
10.5 Software Reset
The CPU may generate an internal 16-clock cycle reset pulse by writing the software reset
sequence 5AH/A5H to the WDRST register. A software reset will set the SWRST bit in WDT-
CON. See “Software Reset” on page 58 for more information on software reset.
11. Power Saving Modes
The AT89LP216 supports two different power-reducing modes: Idle and Power-down. These
modes are accessed through the PCON register.
11.1 Idle Mode
Setting the IDL bit in PCON enters idle mode. Idle mode halts the internal CPU clock. The CPU
state is preserved in its entirety, including the RAM, stack pointer, program counter, program
status word, and accumulator. The Port pins hold the logic states they had at the time that Idle
was activated. Idle mode leaves the peripherals running in order to allow them to wake up the
CPU when an interrupt is generated. The timers, UART, SPI, and GPI blocks continue to func-
tion during Idle. The comparator and watchdog may be selectively enabled or disabled during
Idle. Any enabled interrupt source or reset may terminate Idle mode. When exiting Idle mode
with an interrupt, the interrupt will immediately be serviced, and following RETI the next instruc-
tion to be executed will be the one following the instruction that put the device into Idle.
11.2 Power-down Mode
Setting the Power-down (PD) bit in PCON enters Power-down mode. Power-down mode stops
the oscillator, disables the BOD and powers down the Flash memory in order to minimize power
consumption. Only the power-on circuitry will continue to draw power during Power-down. Dur-
ing Power-down, the power supply voltage may be reduced to the RAM keep-alive voltage. The
RAM contents will be retained, but the SFR contents are not guaranteed once VCC has been
reduced. Power-down may be exited by external reset, power-on reset, or certain interrupts.
11.2.1 Interrupt Recovery from Power-down
Three external interrupts may be configured to terminate Power-down mode. XTAL1 or XTAL2,
when not used for the crystal oscillator or external clock, may be used to exit Power-down
through external interrupts INT0 (P3.2) and INT1 (P3.3). To wake up by external interrupt INT0
or INT1, that interrupt must be enabled and configured for level-sensitive operation. General
purpose interrupt 3 (GPI3) can also wake up the device when the RST pin is disabled. GPI3
must be enabled and configured for low level detection in order to terminate Power-down.
When terminating Power-down by an interrupt, two different wake-up modes are available.
When PWDEX in PCON is zero, the wake-up period is internally timed as shown in Figure 11-1.
At the falling edge on the interrupt pin, Power-down is exited, the oscillator is restarted, and an
internal timer begins counting. The internal clock will not be allowed to propagate to the CPU
until after the timer has timed out. After the time-out period the interrupt service routine will
begin. The time-out period is controlled by the Start-up Timer Fuses (see Table 10-1 on page
15). The interrupt pin need not remain low for the entire time-out period.
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AT89LP216
Figure 11-1. Interrupt Recovery from Power-down (PWDEX = 0)
When PWDEX = “1”, the wake-up period is controlled externally by the interrupt. Again, at the
falling edge on the interrupt pin, power-down is exited and the oscillator is restarted. However,
the internal clock will not propagate until the rising edge of the interrupt pin as shown in Figure
11-2. The interrupt pin should be held low long enough for the selected clock source to stabilize.
After the rising edge on the pin the interrupt service routine will be executed.
Figure 11-2. Interrupt Recovery from Power-down (PWDEX = 1)
11.2.2 Reset Recovery from Power-down
The wake-up from Power-down through an external reset is similar to the interrupt with
PWDEX = “0”. At the falling edge of RST, Power-down is exited, the oscillator is restarted, and
an internal timer begins counting as shown in Figure 11-3. The internal clock will not be allowed
to propagate to the CPU until after the timer has timed out. The time-out period is controlled by
the Start-up Timer Fuses. (See Table 10-1 on page 15). If RST returns high before the time-out,
a two clock cycle internal reset is generated when the internal clock restarts. Otherwise the
device will remain in reset until RST is brought high.
Figure 11-3. Reset Recovery from Power-down.
PWD
INT1
XTAL1
tSUT
Internal
Clock
PWD
INT1
XTAL1
Internal
Clock
PWD
RST
XTAL1
tSUT
Internal
Clock
Internal
Reset
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12. Interrupts
The AT89LP216 provides 7 interrupt sources: two external interrupts, two timer interrupts, a
serial port interrupt, a general-purpose interrupt, and an analog comparator interrupt. These
interrupts and the system reset each have a separate program vector at the start of the program
memory space. Each interrupt source can be individually enabled or disabled by setting or clear-
ing a bit in the interrupt enable register IE. The IE register also contains a global disable bit, EA,
which disables all interrupts.
Each interrupt source (except the analog comparator) can be individually programmed to one of
four priority levels by setting or clearing bits in the interrupt priority registers IP and IPH. The
analog comparator is fixed at the lowest priority level. An interrupt service routine in progress
can be interrupted by a higher priority interrupt, but not by another interrupt of the same or lower
priority. The highest priority interrupt cannot be interrupted by any other interrupt source. If two
requests of different priority levels are pending at the end of an instruction, the request of higher
priority level is serviced. If requests of the same priority level are pending at the end of an
instruction, an internal polling sequence determines which request is serviced. The polling
sequence is based on the vector address; an interrupt with a lower vector address has higher
priority than an interrupt with a higher vector address. Note that the polling sequence is only
used to resolve pending requests of the same priority level.
The External Interrupts INT0 and INT1 can each be either level-activated or edge-activated,
depending on bits IT0 and IT1 in Register TCON. The flags that actually generate these inter-
rupts are the IE0 and IE1 bits in TCON. When the service routine is vectored to, hardware clears
the flag that generated an external interrupt only if the interrupt was edge-activated. If the inter-
rupt was level activated, then the external requesting source (rather than the on-chip hardware)
controls the request flag.
Table 11-1. PCON – Power Control Register
PCON = 87H Reset Value = 000X 0000B
Not Bit Addressable
SMOD1 SMOD0 PWDEX POF GF1 GF0 PD IDL
Bit76543210
Symbol Function
SMOD1 Double Baud Rate bit. Doubles the baud rate of the UART in Modes 1, 2, or 3.
SMOD0 Frame Error Select. When SMOD0 = 1, SCON.7 is SM0. When SMOD0 = 1, SCON.7 is FE. Note that FE will be set after
a frame error regardless of the state of SMOD0.
PWDEX Power-down Exit Mode. When PWDEX = 1, wake up from Power-down is externally controlled. When PWDEX = 1, wake
up from Power-down is internally timed.
POF Power Off Flag. POF is set to “1” during power up (i.e. cold reset). It can be set or reset under software control and is not
affected by RST or BOD (i.e. warm resets).
GF1, GF0 General-purpose Flags
PD Power-down bit. Setting this bit activates power-down operation.
IDL Idle Mode bit. Setting this bit activates Idle mode operation
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The Timer 0 and Timer 1 Interrupts are generated by TF0 and TF1, which are set by a rollover in
their respective Timer/Counter registers (except for Timer 0 in Mode 3). When a timer interrupt is
generated, the on-chip hardware clears the flag that generated it when the service routine is
vectored to.
The Serial Port Interrupt is generated by the logic OR of RI and TI in SCON plus SPIF in SPSR.
None of these flags is cleared by hardware when the service routine is vectored to. In fact, the
service routine normally must determine whether RI, TI, or SPIF generated the interrupt, and the
bit must be cleared by software.
A logic OR of all eight flags in the GPIF register causes the general-purpose interrupt. None of
these flags is cleared by hardware when the service routine is vectored to. The service routine
must determine which bit generated the interrupt, and the bit must be cleared in software. If the
interrupt was level activated, then the external requesting source must de-assert the interrupt
before the flag may be cleared by software.
The CF bit in ACSR generates the Comparator Interrupt. The flag is not cleared by hardware
when the service routine is vectored to and must be cleared by software.
Most of the bits that generate interrupts can be set or cleared by software, with the same result
as though they had been set or cleared by hardware. That is, interrupts can be generated and
pending interrupts can be canceled in software. The two exceptions are the SPI interrupt flag
SPIF and the general-purpose interrupt flags in GPIF. These flags are only set by hardware and
may only be cleared by software.
Table 12-1. Interrupt Vector Addresses
Interrupt Source Vector Address
System Reset RST or POR or BOD 0000H
External Interrupt 0 IE0 0003H
Timer 0 Overflow TF0 000BH
External Interrupt 1 IE1 0013H
Timer 1 Overflow TF1 001BH
Serial Port RI or TI or SPIF 0023H
General-purpose Interrupt GPIF 002BH
Analog Comparator CF 0033H
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12.1 Interrupt Response Time
The interrupt flags may be set by their hardware in any clock cycle. The interrupt controller polls
the flags in the last clock cycle of the instruction in progress. If one of the flags was set in the
preceding cycle, the polling cycle will find it and the interrupt system will generate an LCALL to
the appropriate service routine as the next instruction, provided that the interrupt is not blocked
by any of the following conditions: an interrupt of equal or higher priority level is already in prog-
ress; the instruction in progress is RETI or any write to the IE, IP, or IPH registers. Either of
these conditions will block the generation of the LCALL to the interrupt service routine. The sec-
ond condition ensures that if the instruction in progress is RETI or any access to IE, IP or IPH,
then at least one more instruction will be executed before any interrupt is vectored to. The poll-
ing cycle is repeated at the last cycle of each instruction, and the values polled are the values
that were present at the previous clock cycle. If an active interrupt flag is not being serviced
because of one of the above conditions and is no longer active when the blocking condition is
removed, the denied interrupt will not be serviced. In other words, the fact that the interrupt flag
was once active but not serviced is not remembered. Every polling cycle is new.
If a request is active and conditions are met for it to be acknowledged, a hardware subroutine
call to the requested service routine will be the next instruction executed. The call itself takes
four cycles. Thus, a minimum of five complete clock cycles elapsed between activation of an
interrupt request and the beginning of execution of the first instruction of the service routine. A
longer response time results if the request is blocked by one of the previously listed conditions. If
an interrupt of equal or higher priority level is already in progress, the additional wait time
depends on the nature of the other interrupt's service routine. If the instruction in progress is not
in its final clock cycle, the additional wait time cannot be more than 3 cycles, since the longest
are only 4 cycles long. If the instruction in progress is RETI or an access to IE or IP, the addi-
tional wait time cannot be more than 7 cycles (a maximum of three more cycles to complete the
instruction in progress, plus a maximum of 4 cycles to complete the next instruction). Thus, in a
single-interrupt system, the response time is always more than 5 clock cycles and less than
13 clock cycles. See Figures 12-1 and 12-2.
Figure 12-1. Minimum Interrupt Response Time
Figure 12-2. Maximum Interrupt Response Time
Clock Cycles
INT0
IE0
15
Instruction LCALL 1st ISR Instr.Cur. Instr.
Ack.
Clock Cycles
INT0
IE0
113
Instruction RETI 4 Cyc. Instr. LCALL 1st ISR In
Ack.
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.
Table 12-2. IE – Interrupt Enable Register
IE = A8H Reset Value = 0000 0000B
Bit Addressable
EA EC EGP ES ET1 EX1 ET0 EX0
Bit76543210
Symbol Function
EA Global enable/disable. All interrupts are disabled when EA = 0. When EA = 1, each interrupt source is enabled/disabled
by setting /clearing its own enable bit.
EC Comparator Interrupt Enable
EGP General-purpose Interrupt Enable
ES Serial Port Interrupt Enable
ET1 Timer 1 Interrupt Enable
EX1 External Interrupt 1 Enable
ET0 Timer 0 Interrupt Enable
EX0 External Interrupt 0 Enable
Table 12-3. IP – Interrupt Priority Register
IP = B8H Reset Value = X000 0000B
Bit Addressable
– – PGP PS PT1 PX1 PT0 PX0
Bit76543210
Symbol Function
PGP General-purpose Interrupt Priority Low
PS Serial Port Interrupt Priority Low
PT1 Timer 1 Interrupt Priority Low
PX1 External Interrupt 1 Priority Low
PT0 Timer 0 Interrupt Priority Low
PX0 External Interrupt 0 Priority Low
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13. I/O Ports
The AT89LP216 can be configured for between 11 and 14 I/O pins. The exact number of I/O
pins available depends on the clock and reset options as shown in Table 13-1. All port pins are
5V tolerant as inputs, that is they can be pulled up or driven to 5.5V even when operating at a
lower VCC such as 3V. Inputs use CMOS levels while outputs use TTL levels. An external pul-
lup is required to convert outputs to CMOS levels.
13.1 Port Configuration
All port pins on the AT89LP216 may be configured to one of four modes: quasi-bidirectional
(standard 8051 port outputs), push-pull output, open-drain output, or input-only. Port modes may
be assigned in software on a pin-by-pin basis as shown in Table 13-2. The Tristate-Port User
Fuse determines the default state of the port pins. When the fuse is enabled, all port pins default
to input-only mode after reset, with the exception of P1.4 which starts in quasi-bidirectional
mode. When the fuse is disabled, all port pins, with the exception of P1.0 and P1.1, default to
quasi-bidirectional mode after reset and are weakly pulled high. Each port pin also has a
Schmitt-triggered input for improved input noise rejection. During Power-down all the Schmitt-
triggered inputs are disabled with the exception of P1.3, P3.2 and P3.3, which may be used to
wake up the device. Therefore P1.3, P3.2 and P3.3 should not be left floating during Power-
down.
Table 12-4. IPH – Interrupt Priority High Register
IPH = B7H Reset Value = X000 0000B
Not Bit Addressable
– – PGH PSH PT1H PX1H PT0H PX0H
Bit76543210
Symbol Function
PGH General-purpose Interrupt Priority High
PSH Serial Port Interrupt Priority High
PT1H Timer 1 Interrupt Priority High
PX1H External Interrupt 1 Priority High
PT0H Timer 0 Interrupt Priority High
PX0H External Interrupt 0 Priority High
Table 13-1. I/O Pin Configurations
Clock Source Reset Option Number of I/O Pins
External Crystal or Resonator External RST Pin 11
No external reset 12
External Clock External RST Pin 12
No external reset 13
Internal RC Oscillator External RST Pin 13
No external reset 14
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13.1.1 Quasi-bidirectional Output
Port pins in quasi-bidirectional output mode function similar to standard 8051 port pins. A Quasi-
bidirectional port can be used both as an input and output without the need to reconfigure the
port. This is possible because when the port outputs a logic high, it is weakly driven, allowing an
external device to pull the pin low. When the pin is driven low, it is driven strongly and able to
sink a large current. There are three pull-up transistors in the quasi-bidirectional output that
serve different purposes. One of these pull-ups, called the “very weak” pull-up, is turned on
whenever the port latch for the pin contains a logic “1”. This very weak pull-up sources a very
small current that will pull the pin high if it is left floating.
A second pull-up, called the “weak” pull-up, is turned on when the port latch for the pin contains
a logic “1” and the pin itself is also at a logic “1” level. This pull-up provides the primary source
current for a quasi-bidirectional pin that is outputting a “1”. If this pin is pulled low by an external
device, this weak pull-up turns off, and only the very weak pull-up remains on. In order to pull the
pin low under these conditions, the external device has to sink enough current to overpower the
weak pull-up and pull the port pin below its input threshold voltage.
The third pull-up is referred to as the “strong” pull-up. This pull-up is used to speed up low-to-
high transitions on a quasi-bidirectional port pin when the port latch changes from a logic “0” to a
logic “1”. When this occurs, the strong pull-up turns on for two CPU clocks quickly pulling the
port pin high. The quasi-bidirectional port configuration is shown in Figure 13-1. The input cir-
cuitry of P1.3, P3.2 and P3.3 is not disabled during Power-down (see Figure 13-3).
Figure 13-1. Quasi-bidirectional Output
Table 13-2. Configuration Modes for Port x, Bit y
PxM0.y PxM1.y Port Mode
0 0 Quasi-bidirectional
0 1 Push-pull Output
1 0 Input Only (High Impedance)
1 1 Open-drain Output
1 Clock Delay
(D Flip-Flop)
Strong Very
Weak Weak
Port
Pin
V
CC
V
CC
V
CC
From Port
Register
Input
Data
PWD
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13.1.2 Input-only Mode
The input only port configuration is shown in Figure 13-2. The output drivers are tristated. The
input includes a Schmitt-triggered input for improved input noise rejection. The input circuitry of
P1.3, P3.2 and P3.3 is not disabled during Power-down (see Figure 13-3). Input pins can be
safely driven to 5.5V even when operating at lower VCC levels; however, the input threshold of
the Schmitt trigger will be set by the VCC level and must be taken into consideration.
Figure 13-2. Input Only
Figure 13-3. Input Only for P1.3, P3.2 and P3.3
13.1.3 Open-drain Output
The open-drain output configuration turns off all pull-ups and only drives the pull-down transistor
of the port pin when the port latch contains a logic “0”. To be used as a logic output, a port con-
figured in this manner must have an external pull-up, typically a resistor tied to VCC. The pull-
down for this mode is the same as for the quasi-bidirectional mode. The open-drain port configu-
ration is shown in Figure 13-4.The input circuitry of P1.3, P3.2 and P3.3 is not disabled during
Power-down (see Figure 13-3). Open-drain pins can be safely pulled high to 5.5V even when
operating at lower VCC levels; however, the input threshold of the Schmitt trigger will be set by
the VCC level and must be taken into consideration.
Figure 13-4. Open-drain Output
13.1.4 Push-pull Output
The push-pull output configuration has the same pull-down structure as both the open-drain and
the quasi-bidirectional output modes, but provides a continuous strong pull-up when the port
latch contains a logic “1”. The push-pull mode may be used when more source current is needed
from a port output. Note that due to the 5V tolerant architecture, the push-pull output will have
reduced output high levels at DC operation and hot temperature. Under AC operation an inte-
grated boost circuit provides more source current. The push-pull port configuration is shown in
Figure 13-5. The input circuitry of P1.3, P3.2 and P3.3 is not disabled during Power-down (see
Figure 13-3).
Port
Pin
Input
Data
PWD
Port
Pin
Input
Data
Port
Pin
From Port
Register
Input
Data
PWD
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Figure 13-5. Push-pull Output
13.2 Port 1 Analog Functions
The AT89LP216 incorporates an analog comparator. In order to give the best analog perfor-
mance and minimize power consumption, pins that are being used for analog functions must
have both their digital outputs and digital inputs disabled. Digital outputs are disabled by putting
the port pins into the input-only mode as described in “Port Configuration” on page 22. Digital
inputs on P1.0 and P1.1 are disabled whenever the Analog Comparator is enabled by setting the
CEN bit in ACSR. CEN forces the PWD input on P1.0 and P1.1 low, thereby disabling the
Schmitt trigger circuitry. P1.0 and P1.1 will always default to input-only mode after reset regard-
less of the state of the Tristate-Port Fuse.
13.3 Port Read-modify-write
A read from a port will read either the state of the pins or the state of the port register depending
on which instruction is used. Simple read instructions will always access the port pins directly.
Read-modify-write instructions, which read a value, possibly modify it, and then write it back, will
always access the port register. This includes bit write instructions such as CLR or SETB as they
actually read the entire port, modify a single bit, then write the data back to the entire port. See
Table 13-3 for a complete list of Read-modify-write instruction which may access the ports.
Port
Pin
V
CC
From Port
Register
Input
Data
PWD
Table 13-3. Port Read-modify-write Instructions
Mnemonic Instruction Example
ANL Logical AND ANL P1, A
ORL Logical OR ORL P1, A
XRL Logical EX-OR XRL P1, A
JBC Jump if bit set and clear bit JBC P3.0, LABEL
CPL Complement bit CPL P3.1
INC Increment INC P1
DEC Decrement DEC P3
DJNZ Decrement and jump if not zero DJNZ P3, LABEL
MOV PX.Y, C Move carry to bit Y of Port X MOV P1.0, C
CLR PX.Y Clear bit Y of Port X CLR P1.1
SETB PX.Y Set bit Y of Port X SETB P3.2
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AT89LP216
13.4 Ports During Powerdown
Due to the 5V tolerant port structure, the output ports may have reduced VOH while the device is
under DC conditions, i.e. in the powerdown state, and at high temperature. It is recommended
that output ports be placed in a low state, if possible, prior to entering powerdown, or else exter-
nal pull-ups can be used to maintain the output at a higher voltage.
13.5 Port Alternate Functions
Most general-purpose digital I/O pins of the AT89LP216 share functionality with the various I/Os
needed for the peripheral units. Table 13-5 lists the alternate functions of the port pins. Alternate
functions are connected to the pins in a logic AND fashion. In order to enable the
alternate function on a port pin, that pin must have a “1” in its corresponding port register bit,
otherwise the input/output will always be “0”. Furthermore, each pin must be configured
for the correct input/output mode as required by its peripheral before it may be used as such.
Table 13-4 shows how to configure a generic pin for use with an alternate function.
Table 13-4. Alternate Function Configurations for Pin y of Port x
PxM0.y PxM1.y Px.y I/O Mode
0 0 1 bidirectional (internal pull-up)
0 1 1 output
1 0 X input
1 1 1 bidirectional (external pull-up)
Table 13-5. Port Pin Alternate Functions
Port Pin
Configuration Bits Alternate
Function NotesPxM0.y PxM1.y
P1.0 P1M0.0 P1M1.0 AIN0 input-only
GPI0
P1.1 P1M0.1 P1M1.1 AIN1 input-only
GPI1
P1.2 P1M0.2 P1M1.2 GPI2
P1.3 P1M0.3 P1M1.3 GPI3 RST must be disabled
P1.4 P1M0.4 P1M1.4 SS Resets to quasi-bidirectional
GPI4
P1.5 P1M0.5 P1M1.5 MOSI
GPI5
P1.6 P1M0.6 P1M1.6 MISO
GPI6
P1.7 P1M0.7 P1M1.7 SCK
GPI7
P3.0 P3M0.0 P3M1.0 RXD
P3.1 P3M0.1 P3M1.1 TXD
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14. Enhanced Timer/Counters
The AT89LP216 has two 16-bit Timer/Counter registers: Timer 0 and Timer 1. As a Timer, the
register increase every clock cycle by default. Thus, the register counts clock cycles. Since a
clock cycle consists of one oscillator period, the count rate is equal to the oscillator frequency.
The timer rate can be prescaled by a value between 1 and 16 using the Timer Prescaler (see
Table 9-2 on page 13). Both Timers share the same prescaler.
As a Counter, the register is incremented in response to a l-to-0 transition at its corresponding
input pin, T0 or T1. The external input is sampled every clock cycle. When the samples show a
high in one cycle and a low in the next cycle, the count is incremented. The new count value
appears in the register during the cycle following the one in which the transition was detected.
Since 2 clock cycles are required to recognize a l-to-0 transition, the maximum count rate is 1/2
of the oscillator frequency. There are no restrictions on the duty cycle of the input signal, but it
should be held for at least one full clock cycle to ensure that a given level is sampled at least
once before it changes.
Furthermore, the Timer or Counter functions for Timer 0 and Timer 1 have four operating modes:
variable width timer, 16-bit auto-reload timer, 8-bit auto-reload timer, and split timer. The control
bits C/T in the Special Function Register TMOD select the Timer or Counter function. The bit
pairs (M1, M0) in TMOD select the operating modes.
14.1 Mode 0 – Variable Width Timer/Counter
Both Timers in Mode 0 are 8-bit Counters with a variable prescaler. The prescaler may vary from
1 to 8 bits depending on the PSC bits in TCONB, giving the timer a range of 9 to 16 bits.
By default the timer is configured as a 13-bit timer compatible to Mode 0 in the standard 8051.
Figure 14-1 shows the Mode 0 operation as it applies to Timer 1 in 13-bit mode. As the count
rolls over from all “1”s to all “0”s, it sets the Timer interrupt flag TF1. The counter input is enabled
to the Timer when TR1 = 1 and either GATE = 0 or INT1 = 1. Setting GATE = 1 allows the Timer
to be controlled by external input INT1, to facilitate pulse width measurements. TR1 is a control
bit in the Special Function Register TCON. GATE is in TMOD. The 13-bit register consists of all
8 bits of TH1 and the lower 5 bits of TL1. The upper 3 bits of TL1 are indeterminate and should
be ignored. Setting the run flag (TR1) does not clear the registers.
Note: RH1/RL1 are not required by Timer 1 during Mode 0 and may be used as temporary storage
registers.
P3.2 P3M0.2 P3M1.2 INT0 Internal RC Oscillator Only
P3.3 P3M0.3 P3M1.3 INT1 Internal RC Oscillator or
External Clock Source Only
CLKOUT
P3.4 P3M0.4 P3M1.4 T0
P3.5 P3M0.5 P3M1.5 T1
P3.6 not configurable CMPOUT Pin is tied to comparator output
Table 13-5. Port Pin Alternate Functions (Continued)
Port Pin
Configuration Bits Alternate
Function NotesPxM0.y PxM1.y
Mode 0: Time-out Period 256 2PSC0 1+
×
Oscillator Frequency
-------------------------------------------------------TPS 1+()×=
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3621E–MICRO–11/10
AT89LP216
Figure 14-1. Timer/Counter 1 Mode 0: Variable Width Counter
Mode 0 operation is the same for Timer 0 as for Timer 1, except that TR0, TF0 and INT0 replace
the corresponding Timer 1 signals in Figure 14-1. There are two different GATE bits, one for
Timer 1 (TMOD.7) and one for Timer 0 (TMOD.3). The INT0 and INT1 pins are shared with the
XTAL oscillator. They may only be used for the GATE function when using the internal RC oscil-
lator as the system clock.
14.2 Mode 1 – 16-bit Auto-Reload Timer/Counter
In Mode 1 the Timers are configured for 16-bit auto-reload. The Timer register is run with all
16 bits. The 16-bit reload value is stored in the high and low reload registers (RH1/RL1). The
clock is applied to the combined high and low timer registers (TH1/TL1). As clock pulses are
received, the timer counts up: 0000H, 0001H, 0002H, etc. An overflow occurs on the FFFFH-to-
0000H transition, upon which the timer register is reloaded with the value from RH1/RL1 and the
overflow flag bit in TCON is set. See Figure 14-2. The reload registers default to 0000H, which
gives the full 16-bit timer period compatible with the standard 8051. Mode 1 operation is the
same for Timer/Counter 0.
Figure 14-2. Timer/Counter 1 Mode 1: 16-bit Auto-reload
OSC
T1 Pin
TR1
GATE
INT1 Pin
TL1
(8 Bits)
Control
Interrupt
C/T = 0
C/T = 1
PSC1
TH1
(8 Bits)
TF1
÷TPS
Mode 1: Time-out Period 65536 RH0 RL0{,}–()
Oscillator Frequency
--------------------------------------------------------- TPS 1+()×=
OSC
T1 Pin
TR1
GATE
INT1 Pin
TL1
(8 Bits)
Control
Interrupt
C/T = 0
C/T =1
TH1
(8 Bits)
TF1
RL1
(8 Bits)
RH1
(8 Bits)
Reload
÷TPS
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14.3 Mode 2 – 8-bit Auto-reload Timer/Counter
Mode 2 configures the Timer register as an 8-bit Counter (TL1) with automatic reload, as shown
in Figure 14-3. Overflow from TL1 not only sets TF1, but also reloads TL1 with the contents of
TH1, which is preset by software. The reload leaves TH1 unchanged. Mode 2 operation is the
same for Timer/Counter 0.
Figure 14-3. Timer/Counter 1 Mode 2: 8-bit Auto-reload
Note: RH1/RL1 are not required by Timer 1 during Mode 2 and may be used as temporary storage
registers.
14.4 Mode 3 – 8-bit Split Timer
Timer 1 in Mode 3 simply holds its count. The effect is the same as setting TR1 = 0. Timer 0 in
Mode 3 establishes TL0 and TH0 as two separate counters. The logic for Mode 3 on Timer 0 is
shown in Figure 14-4. TL0 uses the Timer 0 control bits: C/T, GATE, TR0, INT0, and TF0. TH0 is
locked into a timer function (counting machine cycles) and takes over the use of TR1 and TF1
from Timer 1. Thus, TH0 now controls the Timer 1 interrupt. While Timer 0 is in Mode 3, Timer 1
will still obey its settings in TMOD but cannot generate an interrupt.
Mode 3 is for applications requiring an extra 8-bit timer or counter. With Timer 0 in Mode 3, the
AT89LP216 can appear to have three Timer/Counters. When Timer 0 is in Mode 3, Timer 1 can
be turned on and off by switching it out of and into its own Mode 3. In this case, Timer 1 can still
be used by the serial port as a baud rate generator or in any application not requiring an
interrupt.
Figure 14-4. Timer/Counter 0 Mode 3: Two 8-bit Counters
Note: RH0/RL0 are not required by Timer 0 during Mode 3 and may be used as temporary storage
registers.
Mode 2: Time-out Period 256 TH0–()
Oscillator Frequency
-------------------------------------------------------TPS 1+()×=
OSC
T1 Pin
TR1
GATE
TF1
TL1
(8 Bits)
TH1
(8 Bits)
Control Reload
Interrupt
INT0 Pin
C/T = 0
C/T = 1
÷TPS
Control
Interrupt
Control
Interrupt
(8 Bits)
(8 Bits)
C/T = 0
C/T =1
T0 Pin
GATE
INT0 Pin
÷TPS
÷TPS
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.
Table 14-1. TCON – Timer/Counter Control Register
TCON = 88H Reset Value = 0000 0000B
Bit Addressable
TF1 TR1 TF0 TR0 IE1 IT1 IE0 IT0
Bit76543210
Symbol Function
TF1 Timer 1 overflow flag. Set by hardware on Timer/Counter overflow. Cleared by hardware when the processor vectors
to interrupt routine.
TR1 Timer 1 run control bit. Set/cleared by software to turn Timer/Counter on/off.
TF0 Timer 0 overflow flag. Set by hardware on Timer/Counter overflow. Cleared by hardware when the processor vectors
to interrupt routine.
TR0 Timer 0 run control bit. Set/cleared by software to turn Timer/Counter on/off.
IE1 Interrupt 1 edge flag. Set by hardware when external interrupt edge detected. Cleared when interrupt processed.
IT1 Interrupt 1 type control bit. Set/cleared by software to specify falling edge/low level triggered external interrupts.
IE0 Interrupt 0 edge flag. Set by hardware when external interrupt edge detected. Cleared when interrupt processed.
IT0 Interrupt 0 type control bit. Set/cleared by software to specify falling edge/low level triggered external interrupts.
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Table 14-2. TMOD: Timer/Counter Mode Control Register
TMOD = 89H Reset Value = 0000 0000B
Not Bit Addressable
GATE C/T M1 M0 GATE C/T M1 M0
76543210
Timer1 Timer0
Gate Gating control when set. Timer/Counter x is enabled only
while INTx pin is high and TRx control pin is set. When
cleared, Timer x is enabled whenever TRx control bit
is set.
Timer 0 gate bit
C/T Timer or Counter Selector cleared for Timer operation
(input from internal system clock). Set for Counter
operation (input from Tx input pin).
Timer 0 counter/timer select bit
M1 Timer 1 Mode bit 1 Timer 0 M1 bit
M0 Timer 1 Mode bit 0 Timer 0 M0 bit
M1 M0 Mode Operating Mode
000Variable 9 - 16-bit Timer mode.
8-bit Timer/Counter THx with TLx as 1 - 8-bit prescaler.
0 1 1 16-bit auto-reload mode.
16-bit Timer/Counters THx and TLx are cascaded; there is no prescaler.
1028-bit auto reload.
8-bit auto-reload Timer/Counter THx holds a value which is to be
reloaded into TLx each time it overflows.
113Split Timer mode.
(Timer 0) TL0 is an 8-bit Timer/Counter controlled by the standard
Timer 0 control bits. TH0 is an 8-bit timer only controlled by Timer 1
control bits.
113(Timer 1) Timer/Counter 1 stopped.
Timer SFR Purpose Address Bit-Addressable
TCON Control 88H Yes
TMOD Mode 89H No
TL0 Timer 0 low-byte 8AH No
TL1 Timer 1 low-byte 8BH No
TH0 Timer 0 high-byte 8CH No
TH1 Timer 1 high-byte 8DH No
TCONB Mode 91H No
RL0 Timer 0 reload low-byte 92H No
RL1 Timer 1 reload low-byte 93H No
RH0 Timer 0 reload high-byte 94H No
RH1 Timer 1 reload high-byte 95H No
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.
14.5 Pulse Width Modulation
On the AT89LP216, Timer 0 and Timer 1 may be independently configured as 8-bit asymmetri-
cal (edge-aligned) pulse width modulators (PWM) by setting the PWM0EN or PWM1EN bits in
TCONB, respectively. In PWM Mode the generated waveform is output on the timer's input pin,
T0 or T1. Therefore, C/T must be set to “0” when in PWM mode. and the T0 (P3.4) and T1 (P3.5)
must be configured in an output mode. The Timer Overflow Flags and Interrupts will continue to
function while in PWM Mode and Timer 1 may still generate the baud rate for the UART. Each
PWM channel has four modes selected by the mode bits in TMOD.
An example waveform for Timer 0 in PWM Mode 0 is shown in Figure 14-5. TH0 acts as an 8-bit
counter while RH0 stores the 8-bit compare value. When TH0 is 00H the PWM output is
set high. When the TH0 count reaches the value stored in RH0 the PWM output is set low.
Therefore, the pulse width is proportional to the value in RH0. To prevent glitches, writes to
RH0 only take effect on the FFH to 00H overflow of TH0. Setting RH0 to 00H will keep the PWM
output low.
Figure 14-5. Asymmetrical Pulse Width Modulation
Table 14-3. TCONB – Timer/Counter Control Register B
TCONB = 91H Reset Value = 0010 0100B
Not Bit Addressable
PWM1EN PWM0EN PSC12 PSC11 PSC10 PSC02 PSC01 PSC00
Bit76543210
Symbol Function
PWM1EN Configures Timer 1 for Pulse Width Modulation output on T1 (P3.5).
PWM0EN Configures Timer 0 for Pulse Width Modulation output on T0 (P3.4).
PSC12
PSC11
PSC10
Prescaler for Timer 1 Mode 0. The number of active bits in TL1 equals PSC1 + 1. After reset PSC1 = 100B which
enables 5 bits of TL1 for compatibility with the 13-bit Mode 0 in AT89S2051.
PSC02
PSC01
PSC00
Prescaler for Timer 0 Mode 0. The number of active bits in TL0 equals PSC0 + 1. After reset PSC0 = 100B which
enables 5 bits of TL0 for compatibility with the 13-bit Mode 0 in AT89C52.
FFH
00H
RH0
(P3.4)T0
TF0 Set
TH0
time
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AT89LP216
14.5.1 Mode 0 – 8-bit PWM with 8-bit Logarithmic Prescaler
In Mode 0, TLx acts as a logarithmic prescaler driving 8-bit counter THx (see Figure 14-6). The
PSCx bits in TCONB control the prescaler value. On THx overflow, the duty cycle value in RHx
is transferred to OCRx and the output pin is set high. When the count in THx matches OCRx, the
output pin is cleared low. The following formulas give the output frequency and duty cycle for
Timer 0 in PWM Mode 0. Timer 1 in PWM Mode 0 is identical to Timer 0.
Figure 14-6. Timer/Counter 1 PWM Mode 0
14.5.2 Mode 1 – 8-bit PWM with 8-bit Linear Prescaler
In Mode 1, TLx provides linear prescaling with an 8-bit auto-reload from RLx (see Figure 14-7 on
page 34). On TLx overflow, TLx is loaded with the value of RLx. THx acts as an 8-bit counter. On
THx overflow, the duty cycle value in RHx is transferred to OCRx and the output pin is set high.
When the count in THx matches OCRx, the output pin is cleared low. The following formulas
give the output frequency and duty cycle for Timer 0 in PWM Mode 1. Timer 1 in PWM Mode 1 is
identical to Timer 0.
14.5.3 Mode 2 – 8-bit Frequency Generator
Timer 0 in PWM Mode 2 functions as an 8-bit auto-reload timer, the same as normal Mode 2,
with the exception that the output pin T0 is toggled at every TL0 overflow (see Figures 14-8 and
14-9). Timer 1 in PWM Mode 2 is identical to Timer 0. PWM Mode 2 can be used to output a
square wave of varying frequency. THx acts as an 8-bit counter. The following formula gives the
output frequency for Timer 0 in PWM Mode 2.
Mode 0:
fout Oscillator Frequency
256 2PSC0 1+
×
-------------------------------------------------------1
TPS 1+
---------------------
×=
Duty Cycle % 100 RH0
256
------------
×=
OSC
TR1
GATE
INT1 Pin
TL1
(8 Bits)
Control
PSC1 TH1
(8 Bits)
OCR1
RH1
(8 Bits)
=
T1
÷TPS
Mode 1:
fout Oscillator Frequency
256 256 RL0–()×
-------------------------------------------------------1
TPS 1+
---------------------
×=
Duty Cycle % 100 RH0
256
------------
×=
Mode 2: fout Oscillator Frequency
2256TH0–()×
-------------------------------------------------------1
TPS 1+
---------------------
×=
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AT89LP216
Figure 14-7. Timer/Counter 1 PWM Mode 1
Figure 14-8. Timer/Counter 1 PWM Mode 2
Note: {RH0 & RL0}/{RH1 & RL1} are not required by Timer 0/Timer 1 during PWM Mode 2 and may be
used as temporary storage registers.
Figure 14-9. PWM Mode 2 Waveform
OSC
TR1
GATE
INT1 Pin
TL1
(8 Bits)
Control
TH1
(8 Bits)
OCR1
RH1
(8 Bits)
=
T1
RL1
(8 Bits)
÷TPS
OSC
TR1
GATE
INT1 Pin
TL1
(8 Bits)
Control
T1
TH1
(8 Bits)
÷TPS
Tx
THx
FFh
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14.5.4 Mode 3 – Split 8-bit PWM
Timer 1 in PWM Mode 3 simply holds its count. The effect is the same as setting TR1 = 0.
Timer 0 in PWM Mode 3 establishes TL0 and TH0 as two separate PWM counters in a manner
similar to normal Mode 3. PWM Mode 3 on Timer 0 is shown in Figure 14-10. Only the Timer
Prescaler is available to change the output frequency during PWM Mode 3. TL0 can use the
Timer 0 control bits: GATE, TR0, INT0, PWM0EN and TF0. TH0 is locked into a timer function
and uses TR1, PWM1EN and TF1. RL0 provides the duty cycle for TL0 and RH0 provides the
duty cycle for TH0.
PWM Mode 3 is for applications requiring a single PWM channel and two timers, or two PWM
channels and an extra timer or counter. With Timer 0 in PWM Mode 3, the AT89LP216 can
appear to have three Timer/Counters. When Timer 0 is in PWM Mode 3, Timer 1 can be turned
on and off by switching it out of and into its own Mode 3. In this case, Timer 1 can still be used by
the serial port as a baud rate generator or in any application not requiring an interrupt. The fol-
lowing formulas give the output frequency and duty cycle for Timer 0 in PWM Mode 3.
Figure 14-10. Timer/Counter 0 PWM Mode 3
Mode 3: fout Oscillator Frequency
256
-------------------------------------------------------1
TPS 1+
---------------------
×=
Mode 3, T0: Duty Cycle % 100 RL0
256
-----------
×=
Mode 3, T1: Duty Cycle % 100 RH0
256
------------
×=
OSC
TR0
GATE
INT0 Pin
Control
TL0
(8 Bits)
OCR0
RL0
(8 Bits)
=
T0
OSC TH0
(8 Bits)
OCR1
RH0
(8 Bits)
=
T1
TR1
÷TPS
÷TPS
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15. External Interrupts
When the AT89LP216 is configured to use the internal RC Oscillator, XTAL1 and XTAL2 may be
used as the INT0 and INT1 external interrupt sources. When the external clock source is used,
XTAL2 is available as INT1. Neither interrupt is available in crystal oscillator mode.The external
interrupts can be programmed to be level-activated or transition-activated by setting or clearing
bit IT1 or IT0 in Register TCON. If ITx = 0, external interrupt x is triggered by a detected low at
the INTx pin. If ITx = 1, external interrupt x is edge-triggered. In this mode if successive samples
of the INTx pin show a high in one cycle and a low in the next cycle, interrupt request flag IEx in
TCON is set. Flag bit IEx then requests the interrupt. Since the external interrupt pins are sam-
pled once each clock cycle, an input high or low should hold for at least 2 oscillator periods to
ensure sampling. If the external interrupt is transition-activated, the external source has to hold
the request pin high for at least two clock cycles, and then hold it low for at least two clock cycles
to ensure that the transition is seen so that interrupt request flag IEx will be set. IEx will be auto-
matically cleared by the CPU when the service routine is called if generated in edge-triggered
mode. If the external interrupt is level-activated, the external source has to hold the request
active until the requested interrupt is actually generated. Then the external source must deacti-
vate the request before the interrupt service routine is completed, or else another interrupt will
be generated.
16. General-purpose Interrupts
The General-purpose Interrupt (GPI) function provides 8 configurable external interrupts on
Port 1. Each port pin can detect high/low levels or positive/negative edges. The GPIEN register
select which bits of Port 1 are enabled to generate an interrupt. The GPMOD and GPLS regis-
ters determine the mode for each individual pin. GPMOD selects between level-sensitive and
edge-triggered mode. GPLS selects between high/low in level mode and positive/negative in
edge mode. The pins of Port 1 are sampled every clock cycle. In level-sensitive mode, a valid
level must appear in two successive samples before generating the interrupt. In edge-triggered
mode, a transition will be detected if the value changes from one sample to the next. When an
interrupt condition on a pin is detected, and that pin is enabled, the appropriate flag in the GPIF
register is set. The flags in GPIF must be cleared by software.
.
Table 16-1. GPMOD – General-purpose Interrupt Mode Register
GPMOD = 9AH Reset Value = 0000 0000B
Not Bit Addressable
GPMOD7 GPMOD6 GPMOD5 GPMOD4 GPMOD3 GPMOD2 GPMOD1 GPMOD0
Bit76543210
GPMOD.x 0 = level-sensitive interrupt for P1.x
1 = edge-triggered interrupt for P1.x
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AT89LP216
.
.
Table 16-2. GPLS – General-purpose Interrupt Level Select Register
GPLS = 9BH Reset Value = 0000 0000B
Not Bit Addressable
GPLS7 GPLS6 GPLS5 GPLS4 GPLS3 GPLS2 GPLS1 GPLS0
Bit76543210
GPMOD.x 0 = detect low level or negative edge on P1.x
1 = detect high level or positive edge on P1.x
Table 16-3. GPIEN – General-purpose Interrupt Enable Register
GPIEN = 9CH Reset Value = 0000 0000B
Not Bit Addressable
GPIEN7 GPIEN6 GPIEN5 GPIEN4 GPIEN3 GPIEN2 GPIEN1 GPIEN0
Bit76543210
GPIEN.x 0 = interrupt for P1.x disabled
1 = interrupt for P1.x enabled
Table 16-4. GPIF – General-purpose Interrupt Flag Register
GPIF = 9DH Reset Value = 0000 0000B
Not Bit Addressable
GPIF7 GPIF6 GPIF5 GPIF4 GPIF3 GPIF2 GPIF1 GPIF0
Bit76543210
GPIF.x 0 = interrupt on P1.x inactive
1 = interrupt on P1.x active. Must be cleared by software.
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17. Serial Interface
The serial interface on the AT89LP216 implements a Universal Asynchronous Receiver/Trans-
mitter (UART). The UART has the following features:
• Full Duplex Operation
• 8 or 9 Data Bits
• Framing Error Detection
• Multiprocessor Communication Mode with Automatic Address Recognition
• Baud Rate Generator Using Timer 1
• Interrupt on Receive Buffer Full or Transmission Complete
The serial interface is full duplex, which means it can transmit and receive simultaneously. It is
also receive-buffered, which means it can begin receiving a second byte before a previously
received byte has been read from the receive register. (However, if the first byte still has not
been read when reception of the second byte is complete, one of the bytes will be lost.) The
serial port receive and transmit registers are both accessed at the Special Function Register
SBUF. Writing to SBUF loads the transmit register, and reading SBUF accesses a physically
separate receive register. The serial port can operate in the following four modes.
•Mode 0: Serial data enters and exits through RXD. TXD outputs the shift clock. Eight data
bits are transmitted/received, with the LSB first. The baud rate is fixed at 1/2 the oscillator
frequency.
•Mode 1: 10 bits are transmitted (through TXD) or received (through RXD): a start bit (0),
8 data bits (LSB first), and a stop bit (1). On receive, the stop bit goes into RB8 in the Special
Function Register SCON. The baud rate is variable based on Timer 1.
•Mode 2: 11 bits are transmitted (through TXD) or received (through RXD): a start bit (0),
8 data bits (LSB first), a programmable 9th data bit, and a stop bit (1). On transmit, the 9th
data bit (TB8 in SCON) can be assigned the value of “0” or “1”. For example, the parity bit
(P, in the PSW) can be moved into TB8. On receive, the 9th data bit goes into RB8 in the
Special Function Register SCON, while the stop bit is ignored. The baud rate is
programmable to either 1/16 or 1/32 the oscillator frequency.
•Mode 3: 11 bits are transmitted (through TXD) or received (through RXD): a start bit (0),
8 data bits (LSB first), a programmable 9th data bit, and a stop bit (1). In fact, Mode 3 is the
same as Mode 2 in all respects except the baud rate, which is variable based on Timer 1 in
Mode 3.
In all four modes, transmission is initiated by any instruction that uses SBUF as a destination
register. Reception is initiated in Mode 0 by the condition RI = 0 and REN = 1. Reception is initi-
ated in the other modes by the incoming start bit if REN = 1.
17.1 Multiprocessor Communications
Modes 2 and 3 have a special provision for multiprocessor communications. In these modes,
9 data bits are received, followed by a stop bit. The 9th bit goes into RB8. Then comes a stop bit.
The port can be programmed such that when the stop bit is received, the serial port interrupt is
activated only if RB8 = 1. This feature is enabled by setting bit SM2 in SCON.
The following example shows how to use the serial interrupt for multiprocessor communications.
When the master processor must transmit a block of data to one of several slaves, it first sends
out an address byte that identifies the target slave. An address byte differs from a data byte in
that the 9th bit is “1” in an address byte and “0” in a data byte. With SM2 = 1, no slave is
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3621E–MICRO–11/10
AT89LP216
interrupted by a data byte. An address byte, however, interrupts all slaves. Each slave can
examine the received byte and see if it is being addressed. The addressed slave clears its SM2
bit and prepares to receive the data bytes that follows. The slaves that are not addressed set
their SM2 bits and ignore the data bytes. See “Automatic Address Recognition” on page 48.
The SM2 bit has no effect in Mode 0 but can be used to check the validity of the stop bit in
Mode 1. In a Mode 1 reception, if SM2 = 1, the receive interrupt is not activated unless a valid
stop bit is received.
Notes: 1. SMOD0 is located at PCON.6.
2. fosc = oscillator frequency.
Table 17-1. SCON – Serial Port Control Register
SCON Address = 98H Reset Value = 0000 0000B
Bit Addressable
SM0/FE SM1 SM2 REN TB8 RB8 T1 RI
Bit7 6543210
(SMOD0 = 0/1)(1)
Symbol Function
FE
Framing error bit. This bit is set by the receiver when an invalid stop bit is detected. The FE bit is not cleared by valid
frames and must be cleared by software. The SMOD0 bit must be set to enable access to the FE bit. FE will be set
regardless of the state of SMOD0.
SM0 Serial Port Mode Bit 0, (SMOD0 must = 0 to access bit SM0)
SM1
Serial Port Mode Bit 1
SM2
Enables the Automatic Address Recognition feature in Modes 2 or 3. If SM2 = 1 then Rl will not be set unless the received
9th data bit (RB8) is 1, indicating an address, and the received byte is a Given or Broadcast Address. In Mode 1, if SM2 =
1 then Rl will not be activated unless a valid stop bit was received, and the received byte is a Given or Broadcast Address.
In Mode 0, SM2 should be 0.
REN Enables serial reception. Set by software to enable reception. Clear by software to disable reception.
TB8 The 9th data bit that will be transmitted in Modes 2 and 3. Set or clear by software as desired.
RB8 In Modes 2 and 3, the 9th data bit that was received. In Mode 1, if SM2 = 0, RB8 is the stop bit that was received. In Mode
0, RB8 is not used.
TI Transmit interrupt flag. Set by hardware at the end of the 8th bit time in Mode 0, or at the beginning of the stop bit in the
other modes, in any serial transmission. Must be cleared by software.
RI Receive interrupt flag. Set by hardware at the end of the 8th bit time in Mode 0, or halfway through the stop bit time in the
other modes, in any serial reception (except see SM2). Must be cleared by software.
SM0 SM1 Mode Description Baud Rate(2)
0 0 0 shift register fosc/2
0 1 1 8-bit UART variable (Timer 1)
1 0 2 9-bit UART fosc/32 or fosc/16
1 1 3 9-bit UART variable (Timer 1)
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18. Baud Rates
The baud rate in Mode 0 is fixed as shown in the following equation:
The baud rate in Mode 2 depends on the value of the SMOD1 bit in Special Function Register
PCON.7. If SMOD1 = 0 (the value on reset), the baud rate is 1/32 of the oscillator frequency. If
SMOD1 = 1, the baud rate is 1/16 of the oscillator frequency, as shown in the following equation:
18.0.1 Using Timer 1 to Generate Baud Rates
The Timer 1 overflow rate determines the baud rates in Modes 1 and 3. When Timer 1 is the
baud rate generator, the baud rates are determined by the Timer 1 overflow rate and the value
of SMOD1 according to the following equation:
The Timer 1 interrupt should be disabled in this application. The Timer itself can be configured
for either timer or counter operation in any of its 3 running modes. In the most typical applica-
tions, it is configured for timer operation in auto-reload mode (high nibble of TMOD = 0010B). In
this case, the baud rate is given by the following formula:
Programmers can achieve very low baud rates with Timer 1 by configuring the Timer to run as a
16-bit auto-reload timer (high nibble of TMOD = 0001B). In this case, the baud rate is given by
the following formula.
Table 18-1 lists commonly used baud rates and how they can be obtained from Timer 1.
Mode 0 Baud Rate Oscillator Frequency
2
-------------------------------------------------------=
Mode 2 Baud Rate 2SMOD1
32
-------------------- (Oscillator Frequency)×=
Modes 1, 3
Baud Rate
2SMOD1
32
-------------------- (Timer 1 Overflow Rate)×=
Modes 1, 3
Baud Rate
2SMOD1
32
-------------------- Oscillator Frequency
256 TH1()–[]
-------------------------------------------------------1
TPS 1+
---------------------
××=
Modes 1, 3
Baud Rate
2SMOD1
32
-------------------- Oscillator Frequency
256 RH1 RL1(,)–[]
-------------------------------------------------------
×1
TPS 1+
---------------------
×=
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18.1 More About Mode 0
Serial data enters and exits through RXD. TXD outputs the shift clock. Eight data bits are trans-
mitted/received, with the LSB first. The baud rate is fixed at 1/2 the oscillator frequency. Figure
18-1 on page 42 shows a simplified functional diagram of the serial port in Mode 0 and associ-
ated timing.
Transmission is initiated by any instruction that uses SBUF as a destination register. The “write
to SBUF” signal also loads a “1” into the 9th position of the transmit shift register and tells the TX
Control Block to begin a transmission. The internal timing is such that one full machine cycle will
elapse between “write to SBUF” and activation of SEND.
SEND transfers the output of the shift register to the alternate output function line of P3.0, and
also transfers Shift Clock to the alternate output function line of P3.1. At the falling edge of Shift
Clock the contents of the transmit shift register are shifted one position to the right.
As data bits shift out to the right, “0”s come in from the left. When the MSB of the data byte is at
the output position of the shift register, the “1” that was initially loaded into the 9th position is just
to the left of the MSB, and all positions to the left of that contain “0”s. This condition flags the TX
Control block to do one last shift, then deactivate SEND and set TI.
Reception is initiated by the condition REN = 1 and R1 = 0. At the next clock cycle, the RX Con-
trol unit writes the bits 11111110 to the receive shift register and activates RECEIVE in the next
clock phase.
RECEIVE enables Shift Clock to the alternate output function line of P3.1. At the falling edge of
Shift Clock the contents of the receive shift register are shifted one position to the left. The value
that comes in from the right is the value that was sampled at the P3.0 pin at rising edge of Shift
Clock.
As data bits come in from the right, “1”s shift out to the left. When the “0” that was initially loaded
into the right-most position arrives at the left-most position in the shift register, it flags the RX
Control block to do one last shift and load SBUF. Then RECEIVE is cleared and RI is set.
Table 18-1. Commonly Used Baud Rates Generated by Timer 1 (TPS = 0000B)
Baud Rate fOSC (MHz) SMOD1
Timer 1
C/T Mode Reload Value
Mode 0: 1 MHz 2 X X X X
Mode 2: 375K 12 0 X X X
62.5K 12 1 0 2 F4H
19.2K 11.059 1 0 2 DCH
9.6K 11.059 0 0 2 DCH
4.8K 11.059 0 0 2 B8H
2.4K 11.059 0 0 2 70H
1.2K 11.059 0 0 1 FEE0H
137.5 11.986 0 0 1 F55CH
110 6 0 0 1 F958H
110 12 0 0 1 F304H
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Figure 18-1. Serial Port Mode 0
INTERNAL BUS
1/2 fosc
INTERNAL BUS
TXD (SHIFT CLOCK)
RXD (DATA OUT)
TXD (SHIFT CLOCK)
RXD (DATA IN)
WRITE TO SBUF
SEND
SHIFT
TI
WRITE TO SCON (CLEAR RI)
SHIFT
RECEIVE
RI
“1“
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18.2 More About Mode 1
Ten bits are transmitted (through TXD), or received (through RXD): a start bit (0), 8 data bits
(LSB first), and a stop bit (1). On receive, the stop bit goes into RB8 in SCON. In the
AT89LP216, the baud rate is determined by the Timer 1 overflow rate. Figure 18-2 shows a sim-
plified functional diagram of the serial port in Mode 1 and associated timings for transmit and
receive.
Transmission is initiated by any instruction that uses SBUF as a destination register. The “write
to SBUF” signal also loads a “1” into the 9th bit position of the transmit shift register and flags the
TX Control unit that a transmission is requested. Transmission actually commences at S1P1 of
the machine cycle following the next rollover in the divide-by-16 counter. Thus, the bit times are
synchronized to the divide-by-16 counter, not to the “write to SBUF” signal.
The transmission begins when SEND is activated, which puts the start bit at TXD. One bit time
later, DATA is activated, which enables the output bit of the transmit shift register to TXD. The
first shift pulse occurs one bit time after that.
As data bits shift out to the right, “0”s are clocked in from the left. When the MSB of the data byte
is at the output position of the shift register, the “1” that was initially loaded into the 9th position is
just to the left of the MSB, and all positions to the left of that contain “0”s. This condition flags the
TX Control unit to do one last shift, then deactivate SEND and set TI. This occurs at the tenth
divide-by-16 rollover after “write to SBUF.”
Reception is initiated by a 1-to-0 transition detected at RXD. For this purpose, RXD is sampled
at a rate of 16 times the established baud rate. When a transition is detected, the divide-by-16
counter is immediately reset, and 1FFH is written into the input shift register. Resetting the
divide-by-16 counter aligns its roll-overs with the boundaries of the incoming bit times.
The 16 states of the counter divide each bit time into 16ths. At the 7th, 8th, and 9th counter
states of each bit time, the bit detector samples the value of RXD. The value accepted is the
value that was seen in at least 2 of the 3 samples. This is done to reject noise. In order to reject
false bits, if the value accepted during the first bit time is not 0, the receive circuits are reset and
the unit continues looking for another l-to-0 transition. If the start bit is valid, it is shifted into the
input shift register, and reception of the rest of the frame proceeds.
As data bits come in from the right, “1”s shift out to the left. When the start bit arrives at the left-
most position in the shift register, (which is a 9-bit register in Mode 1), it flags the RX Control
block to do one last shift, load SBUF and RB8, and set RI. The signal to load SBUF and RB8
and to set RI is generated if, and only if, the following conditions are met at the time the final shift
pulse is generated.
RI = 0 and
Either SM2 = 0, or the received stop bit = 1
If either of these two conditions is not met, the received frame is irretrievably lost. If both condi-
tions are met, the stop bit goes into RB8, the 8 data bits go into SBUF, and RI is activated. At
this time, whether or not the above conditions are met, the unit continues looking for a 1-to-0
transition in RXD.
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Figure 18-2. Serial Port Mode 1
TX
CLOCK
WRITE TO SBUF
INTERNAL BUS
READ
SBUF
LOAD
SBUF
SBUF
SHIFT
INPUT SHIFT REG.
(9 BITS)
BIT
DETECTOR
1-TO-0
TRANSITION
DETECTOR
SERIAL
PORT
INTERRUPT
WRITE
TO
SBUF
÷2
SMOD1
= 0
SMOD1
= 1
TIMER 1
OVERFLOW
RXD
RX CLOCK
RX CLOCK
RX CONTROL
START
START DATA
SEND
SAMPLE
÷16
÷16
TX CONTROL
TI
TI
ZERO DETECTOR
SBUF TXD
INTERNAL BUS
“1”
DQ
CL
S
LOAD
SBUF
SHIFT
SHIFT
1FFH
RI
SEND
DATA
SHIFT
TXD
TI
D0 D1 D2 D3 D4 D5 D6 D7
D0 D1 D2 D3 D4 D5 D6 D7
STOP BIT
TRANSMIT
START BIT
÷16 RESET
START BIT STOP BIT
RX
CLOCK
BIT DETECTOR SAMPLE TIMES
SHIFT
RECEIVE
RXD
RI
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18.3 More About Modes 2 and 3
Eleven bits are transmitted (through TXD), or received (through RXD): a start bit (0), 8 data bits
(LSB first), a programmable 9th data bit, and a stop bit (1). On transmit, the 9th data bit (TB8)
can be assigned the value of “0” or “1”. On receive, the 9th data bit goes into RB8 in SCON. The
baud rate is programmable to either 1/16 or 1/32 of the oscillator frequency in Mode 2. Mode 3
may have a variable baud rate generated from Timer 1.
Figures 18-3 and 18-4 show a functional diagram of the serial port in Modes 2 and 3. The
receive portion is exactly the same as in Mode 1. The transmit portion differs from Mode 1 only
in the 9th bit of the transmit shift register.
Transmission is initiated by any instruction that uses SBUF as a destination register. The “write
to SBUF” signal also loads TB8 into the 9th bit position of the transmit shift register and flags the
TX Control unit that a transmission is requested. Transmission commences at S1P1 of the
machine cycle following the next rollover in the divide-by-16 counter. Thus, the bit times are syn-
chronized to the divide-by-16 counter, not to the “write to SBUF” signal.
The transmission begins when SEND is activated, which puts the start bit at TXD. One bit time
later, DATA is activated, which enables the output bit of the transmit shift register to TXD. The
first shift pulse occurs one bit time after that. The first shift clocks a “1” (the stop bit) into the 9th
bit position of the shift register. Thereafter, only “0”s are clocked in. Thus, as data bits shift out to
the right, “0”s are clocked in from the left. When TB8 is at the output position of the shift register,
then the stop bit is just to the left of TB8, and all positions to the left of that contain “0”s. This con-
dition flags the TX Control unit to do one last shift, then deactivate SEND and set TI. This occurs
at the 11th divide-by-16 rollover after “write to SBUF.”
Reception is initiated by a 1-to-0 transition detected at RXD. For this purpose, RXD is sampled
at a rate of 16 times the established baud rate. When a transition is detected, the divide-by-16
counter is immediately reset, and 1FFH is written to the input shift register.
At the 7th, 8th and 9th counter states of each bit time, the bit detector samples the value of RXD.
The value accepted is the value that was seen in at least 2 of the 3 samples. If the value
accepted during the first bit time is not 0, the receive circuits are reset and the unit continues
looking for another l-to-0 transition. If the start bit proves valid, it is shifted into the input shift reg-
ister, and reception of the rest of the frame proceeds.
As data bits come in from the right, “1”s shift out to the left. When the start bit arrives at the left-
most position in the shift register (which in Modes 2 and 3 is a 9-bit register), it flags the RX Con-
trol block to do one last shift, load SBUF and RB8, and set RI. The signal to load SBUF and RB8
and to set RI is generated if, and only if, the following conditions are met at the time the final shift
pulse is generated:
RI = 0, and
Either SM2 = 0 or the received 9th data bit = 1
If either of these conditions is not met, the received frame is irretrievably lost, and RI is not set. If
both conditions are met, the received 9th data bit goes into RB8, and the first 8 data bits go into
SBUF. One bit time later, whether the above conditions were met or not, the unit continues look-
ing for a 1-to-0 transition at the RXD input.
Note that the value of the received stop bit is irrelevant to SBUF, RB8, or RI.
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Figure 18-3. Serial Port Mode 2
SMOD1
1
SMOD1 0
INTERNAL BUS
INTERNAL BUS
CPU CLOCK
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Figure 18-4. Serial Port Mode 3
TX
CLOCK
WRITE TO SBUF
SEND
DATA
SHIFT
TXD
STOP BIT GEN
TI
D0 D1 D2 D3 D4 D5 D6 D7 TB8
STOP BIT
TRANSMIT
START BIT
INTERNAL BUS
READ
SBUF
LOAD
SBUF
SBUF
SHIFT
INPUT SHIFT REG.
(9 BITS)
BIT
DETECTOR
1-TO-0
TRANSITION
DETECTOR
SERIAL
PORT
INTERRUPT
WRITE
TO
SBUF
÷2
SMOD1
= 0
SMOD1
= 1
TIMER 1
OVERFLOW
RXD
RX CLOCK
RX CLOCK
RX CONTROL
START
START DATA
SAMPLE
÷16
÷16
TX CONTROL
TI
ZERO DETECTOR
SBUF TXD
INTERNAL BUS
TB8
DQ
CL
S
LOAD
SBUF
SHIFT
1FFH
SHIFT
RI
SEND
D0 D1 D2 D3 D4 D5 D6 D7 RB8
START BIT
STOP
BIT
÷16 RESET
RX
CLOCK
BIT DETECTOR SAMPLE TIMES
SHIFT
RECEIVE
RXD
RI
STOP BIT
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18.4 Framing Error Detection
In addition to all of its usual modes, the UART can perform framing error detection by looking for
missing stop bits, and automatic address recognition. When used for framing error detect, the
UART looks for missing stop bits in the communication. A missing bit will set the FE bit in the
SCON register. The FE bit shares the SCON.7 bit with SM0 and the function of SCON.7 is deter-
mined by PCON.6 (SMOD0). If SMOD0 is set then SCON.7 functions as FE. SCON.7 functions
as SM0 when SMOD0 is cleared. When used as FE, SCON.7 can only be cleared by software.
The FE bit will be set by a framing error regardless of the state of SMOD0.
18.5 Automatic Address Recognition
Automatic Address Recognition is a feature which allows the UART to recognize certain
addresses in the serial bit stream by using hardware to make the comparisons. This feature
saves a great deal of software overhead by eliminating the need for the software to examine
every serial address which passes by the serial port. This feature is enabled by setting the SM2
bit in SCON. In the 9th bit UART modes, Mode 2 and Mode 3, the Receive Interrupt flag (RI) will
be automatically set when the received byte contains either the “Given” address or the “Broad-
cast” address. The 9th bit mode requires that the 9th information bit to be a “1” to indicate that
the received information is an address and not data.
The 8th bit mode is called Mode 1. In this mode the RI flag will be set if SM2 is enabled and the
information received has a valid stop bit following the 8th address bits and the information is
either a Given or Broadcast address.
Mode 0 is the Shift Register mode and SM2 is ignored.
Using the Automatic Address Recognition feature allows a master to selectively communicate
with one or more slaves by invoking the given slave address or addresses. All of the slaves may
be contacted by using the Broadcast address. Two special Function Registers are used to
define the slave’s address, SADDR, and the address mask, SADEN. SADEN is used to define
which bits in the SADDR are to be used and which bits are “don’t care”. The SADEN mask can
be logically ANDed with the SADDR to create the “Given” address which the master will use for
addressing each of the slaves. Use of the Given address allows multiple slaves to be recognized
while excluding others. The following examples show the versatility of this scheme:
Slave 0 SADDR = 1100 0000
SADEN = 1111 1101
Given = 1100 00X0
Slave 1 SADDR = 1100 0000
SADEN = 1111 1110
Given = 1100 000X
In the previous example, SADDR is the same and the SADEN data is used to differentiate
between the two slaves. Slave 0 requires a “0” in bit 0 and it ignores bit 1. Slave 1 requires a “0”
in bit 1 and bit 0 is ignored. A unique address for slave 0 would be 1100 0010 since slave 1
requires a “0” in bit 1. A unique address for slave 1 would be 1100 0001 since a “1” in bit 0 will
exclude slave 0. Both slaves can be selected at the same time by an address which has bit 0 = 0
(for slave 0) and bit 1 = 0 (for slave 1). Thus, both could be addressed with 1100 0000.
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In a more complex system, the following could be used to select slaves 1 and 2 while excluding
slave 0:
Slave 0 SADDR = 1100 0000
SADEN = 1111 1001
Given = 1100 0XX0
Slave 1 SADDR = 1110 0000
SADEN = 1111 1010
Given = 1110 0X0X
Slave 2 SADDR = 1110 0000
SADEN = 1111 1100
Given = 1110 00XX
In the above example, the differentiation among the 3 slaves is in the lower 3 address bits. Slave
0 requires that bit 0 = 0 and it can be uniquely addressed by 1110 0110. Slave 1 requires that
bit 1 = 0 and it can be uniquely addressed by 1110 and 0101. Slave 2 requires that bit 2 = 0 and
its unique address is 1110 0011. To select Slaves 0 and 1 and exclude Slave 2, use address
1110 0100, since it is necessary to make bit 2 = 1 to exclude slave 2.
The Broadcast Address for each slave is created by taking the logic OR of SADDR and SADEN.
Zeros in this result are trended as don’t cares. In most cases, interpreting the don’t cares as
ones, the broadcast address will be FF hexadecimal.
Upon reset SADDR (SFR address 0A9H) and SADEN (SFR address 0B9H) are loaded with
“0”s. This produces a given address of all “don’t cares” as well as a Broadcast address of all
“don’t cares”. This effectively disables the Automatic Addressing mode and allows the microcon-
troller to use standard 80C51-type UART drivers which do not make use of this feature.
19. Serial Peripheral Interface
The serial peripheral interface (SPI) allows high-speed synchronous data transfer between the
AT89LP216 and peripheral devices or between multiple AT89LP216 devices. The SPI features
include the following:
• Full-duplex, 3-wire Synchronous Data Transfer
• Master or Slave Operation
• Maximum Bit Frequency = fOSC/4
• LSB First or MSB First Data Transfer
• Four Programmable Bit Rates in Master Mode
• End of Transmission Interrupt Flag
• Write Collision Flag Protection
• Double-buffered Receive
• Double-buffered Transmit (Enhanced Mode Only)
• Wake up from Idle Mode (Slave Mode Only)
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The interconnection between master and slave CPUs with SPI is shown in Figure 19-1. The four
pins in the interface are Master-In/Slave-Out (MISO), Master-Out/Slave-In (MOSI), Shift Clock
(SCK), and Slave Select (SS). The SCK pin is the clock output in master mode, but is the clock
input in slave mode. The MSTR bit in SPCR determines the directions of MISO and MOSI. Also
notice that MOSI connects to MOSI and MISO to MISO. In master mode, SS/P1.4 is ignored and
may be used as a general-purpose input or output. In slave mode, SS must be driven low to
select an individual device as a slave. When SS is driven high, the slave’s SPI port is deacti-
vated and the MOSI/P1.5 pin can be used as a general-purpose input.
Figure 19-1. SPI Master-slave Interconnection
The SPI has two modes of operation: normal (non-buffered write) and enhanced (buffered
write). In normal mode, writing to the SPI data register (SPDR) of the master CPU starts the SPI
clock generator and the data written shifts out of the MOSI pin and into the MOSI pin of the slave
CPU. Transmission may start after an initial delay while the clock generator waits for the next full
bit slot of the specified baud rate. After shifting one byte, the SPI clock generator stops, setting
the end of transmission flag (SPIF) and transferring the received byte to the read buffer (SPDR).
If both the SPI interrupt enable bit (SPIE) and the serial port interrupt enable bit (ES) are set, an
interrupt is requested. Note that SPDR refers to either the write data buffer or the read data buf-
fer, depending on whether the access is a write or read. In normal mode, because the write
buffer is transparent (and a write access to SPDR will be directed to the shift buffer), any attempt
to write to SPDR while a transmission is in progress will result in a write collision with WCOL set.
However, the transmission will still complete normally, but the new byte will be ignored and a
new write access to SPDR will be necessary.
Enhanced mode is similar to normal mode except that the write buffer holds the next byte to be
transmitted. Writing to SPDR loads the write buffer and sets WCOL to signify that the buffer is
full and any further writes will overwrite the buffer. WCOL is cleared by hardware when the
buffered byte is loaded into the shift register and transmission begins. If the master SPI is
currently idle, i.e. if this is the first byte, then after loading SPDR, transmission of the byte starts
and WCOL is cleared immediately. While this byte is transmitting, the next byte may be written
to SPDR. The Load Enable flag (LDEN) in SPSR can be used to determine when transmission
has started. LDEN is asserted during the first four bit slots of a SPI transfer. The master CPU
should first check that LDEN is set and that WCOL is cleared before loading the next byte. In
enhanced mode, if WCOL is set when a transfer completes, i.e. the next byte is available, then
the SPI immediately loads the buffered byte into the shift register, resets WCOL, and continues
transmission without stopping and restarting the clock generator. As long as the CPU can keep
the write buffer full in this manner, multiple bytes may be transferred with minimal latency
between bytes.
8-Bit Shift Register
Master Slave
MSBLSBMSBLSB
8-Bit Shift Register
MISOMISO
DISSO
SSIG
MOSIMOSI
SS
SS
GPIO
SCK SCK
Clock
Generator
GPIO
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Notes: 1. Set up the clock mode before enabling the SPI: set all bits needed in SPCR except the SPE bit, then set SPE.
2. Enable the master SPI prior to the slave device.
3. Slave echoes master on the next Tx if not loaded with new data.
Table 19-1. SPCR – SPI Control Register
SPCR Address = E9H Reset Value = 0000 0000B
Not Bit Addressable
SPIE SPE DORD MSTR CPOL CPHA SPR1 SPR0
Bit76543210
Symbol Function
SPIE SPI interrupt enable. This bit, in conjunction with the ES bit in the IE register, enables SPI interrupts: SPIE = 1 and ES = 1
enable SPI interrupts. SPIE = 0 disables SPI interrupts.
SPE SPI enable. SPI = 1 enables the SPI channel and connects SS, MOSI, MISO and SCK to pins P1.4, P1.5, P1.6, and P1.7.
SPI = 0 disables the SPI channel.
DORD Data order. DORD = 1 selects LSB first data transmission. DORD = 0 selects MSB first data transmission.
MSTR Master/slave select. MSTR = 1 selects Master SPI mode. MSTR = 0 selects slave SPI mode.
CPOL Clock polarity. When CPOL = 1, SCK is high when idle. When CPOL = 0, SCK of the master device is low when not
transmitting. Please refer to figure on SPI clock phase and polarity control.
CPHA Clock phase. The CPHA bit together with the CPOL bit controls the clock and data relationship between master and
slave. Please refer to figure on SPI clock phase and polarity control.
SPR0
SPR1
SPI clock rate select. These two bits control the SCK rate of the device configured as master. SPR1 and SPR0 have no
effect on the slave. The relationship between SCK and the oscillator frequency, FOSC., is as follows:
SPR1 SPR0 SCK
00f
OSC/4
01f
OSC/8
10f
OSC/32
11f
OSC/64
Table 19-2. SPDR – SPI Data Register
SPDR Address = EAH
Reset Value = 00H (after cold reset)
unchanged (after warm reset)
Not Bit Addressable
SPD7 SPD6 SPD5 SPD4 SPD3 SPD2 SPD1 SPD0
Bit76543210
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Table 19-3. SPSR – SPI Status Register
SPSR Address = E8H Reset Value = 000X X000B
Not Bit Addressable
SPIF WCOL LDEN – – SSIG DISSO ENH
Bit76543210
Symbol Function
SPIF SP interrupt flag. When a serial transfer is complete, the SPIF bit is set and an interrupt is generated if SPIE = 1 and
ES = 1. The SPIF bit is cleared by reading the SPI status register followed by reading/writing the SPI data register.
WCOL
When ENH = 0: Write collision flag. The WCOL bit is set if the SPI data register is written during a data transfer. During
data transfer, the result of reading the SPDR register may be incorrect, and writing to it has no effect. The WCOL bit
(and the SPIF bit) are cleared by reading the SPI status register followed by reading/writing the SPI data register.
When ENH = 1: WCOL works in Enhanced mode as Tx Buffer Full. Writing during WCOL = 1 in enhanced mode will
overwrite the waiting data already present in the Tx Buffer. In this mode, WCOL is no longer reset by the SPIF reset but
is reset when the write buffer has been unloaded into the serial shift register.
LDEN
Load enable for the Tx buffer in enhanced SPI mode.
When ENH is set, it is safe to load the Tx Buffer while LDEN = 1 and WCOL = 0. LDEN is high during bits 0 - 3 and is low
during bits 4 - 7 of the SPI serial byte transmission time frame.
SSIG
Slave Select Ignore. If SSIG = 0, the SPI will only operate in slave mode if SS (P1.4) is pulled low. When SSIG = 1, the
SPI ignores SS in slave mode and is active whenever SPE (SPCR.6) is set. P1.4 may be used as a regular I/O pin when
SSIG = 1.
DISSO
Disable slave output bit.
When set, this bit causes the MISO pin to be tri-stated so more than one slave device can share the same interface with
a single master. Normally, the first byte in a transmission could be the slave address and only the selected slave should
clear its DISSO bit.
ENH
Enhanced SPI mode select bit. When ENH = 0, SPI is in normal mode, i.e. without write double buffering.
When ENH = 1, SPI is in enhanced mode with write double buffering. The Tx buffer shares the same address with the
SPDR register.
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Figure 19-2. SPI Shift Register Diagram
Figure 19-3. SPI Block Diagram
2:1
MUX
2:1
MUX
Serial Master Serial Slave
LATCH
DQ
CLK
LATCH
DQ
CLK
LATCH
DQ
CLK
LATCH
DQ
CLK
Parallel Slave
(Read Buffer)
Parallel Master
(Write Buffer)
Serial Out
Receive
Byte
Serial In
Transmit
Byte 8 8
8
8
7
8
Oscillator
8-bit Shift Register
Read Data Buffer
Pin Control Logic
SPI Control
SPI Status Register
SPI Interrupt
RequestInternal
Data Bus
Select
SPI Clock (Mater)
Divider
÷4÷8÷32÷64
SPI Control Register
8
8
8
SPIF
WCOL SPR1
MSTR
SPIE
Clock
Logic
Clock
MSB
S
M
SPE
DORD
MSTR
CPOL
CPHA
SPR1
SPR0
MSTR
SPE
DORD
LSB
S
M
M
S
MISO
P1.6
MOSI
P1.5
SCK
1.7
SS
P1.4
SPR0
SPE
Write Data Buffer
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The CPHA (Clock PHAse), CPOL (Clock POLarity), and SPR (Serial Peripheral clock Rate =
baud rate) bits in SPCR control the shape and rate of SCK. The two SPR bits provide four possi-
ble clock rates when the SPI is in master mode. In slave mode, the SPI will operate at the rate of
the incoming SCK as long as it does not exceed the maximum bit rate. There are also four pos-
sible combinations of SCK phase and polarity with respect to the serial data. CPHA and CPOL
determine which format is used for transmission. The SPI data transfer formats are shown in
Figures 19-4 and 19-5. To prevent glitches on SCK from disrupting the interface, CPHA, CPOL,
and SPR should not be modified while the interface is enabled, and the master device should be
enabled before the slave device(s).
Figure 19-4. SPI Transfer Format with CPHA = 0
Note: *Not defined but normally MSB of character just received.
Figure 19-5. SPI Transfer Format with CPHA = 1
Note: *Not defined but normally LSB of previously transmitted character.
MSB 6 5 4 3 2 1 LSB
1 2 3 4 5 6 7 8
MSB
*654321 LSB
SCK CYCLE #
(FOR REFERENCE)
SCK (CPOL = 0)
SCK (CPOL = 1)
MOSI
(FROM MASTER)
MISO
(FROM SLAVE)
SS (TO SLAVE)
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20. Analog Comparator
A single analog comparator is provided on the AT89LP216. The analog comparator has the fol-
lowing features:
• Comparator Output Flag and Interrupt
• Selectable Interrupt Condition
– High- or Low-level
– Rising- or Falling-edge
– Output Toggle
• Hardware Debouncing Modes
Comparator operation is such that the output is a logic “1” when the positive input AIN0 (P1.0]) is
greater than the negative input AIN1 (P1.1). Otherwise the output is a zero. Setting the CEN bit
in ACSR enables the comparator. When the comparator is first enabled, the comparator output
and interrupt flag are not guaranteed to be stable for 10 µs. The corresponding comparator inter-
rupt should not be enabled during that time, and the comparator interrupt flag must be cleared
before the interrupt is enabled in order to prevent an immediate interrupt service. Before
enabling the comparator the analog inputs should be tristated by putting P1.0 and P1.1 into
input-only mode. See “Port 1 Analog Functions” on page 25.
The comparator may be configured to cause an interrupt under a variety of output value condi-
tions by setting the CM bits in ACSR. The comparator interrupt flag CF in ACSR is set whenever
the comparator output matches the condition specified by CM. The flag may be polled by soft-
ware or may be used to generate an interrupt and must be cleared by software.
20.1 Comparator Interrupt with Debouncing
The comparator output is sampled every clock cycle. The conditions on the analog inputs may
be such that the comparator output will toggle excessively. This is especially true if applying slow
moving analog inputs. Three debouncing modes are provided to filter out this noise. In debounc-
ing mode, the comparator uses Timer 1 to modulate its sampling time. When a relevant
transition occurs, the comparator waits until two Timer 1 overflows have occurred before resam-
pling the output. If the new sample agrees with the expected value, CF is set. Otherwise, the
event is ignored. The filter may be tuned by adjusting the time-out period of Timer 1. Because
Timer 1 is free running, the debouncer must wait for two overflows to guarantee that the sam-
pling delay is at least 1 time-out period. Therefore, after the initial edge event, the interrupt may
occur between 1 and 2 time-out periods later. See Figure 20-1 on page 56.
By default the comparator is disabled during Idle mode. To allow the comparator to function dur-
ing Idle, the CIDL bit is ACSR must be set. When CIDL is set, the comparator can be used to
wake-up the CPU from Idle if the comparator interrupt is enabled. The comparator is always dis-
abled during Power-down mode.
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Note: 1. Debouncing modes require the use of Timer 1 to generate the sampling delay.
Figure 20-1. Negative Edge with Debouncing Example
Table 20-1. ACSR – Analog Comparator Control & Status Register
ACSR = 97H Reset Value = XXX0 0000B
Not Bit Addressable
– – CIDL CF CEN CM3 CM1 CM0
Bit76543210
Symbol Function
CIDL Comparator Idle Enable. If CIDL = 1 the comparator will continue to operate during Idle mode. If CIDL = 0 the
comparator is powered down during Idle mode. The comparator is always shut down during Power-down mode.
CF Comparator Interrupt Flag. Set when the comparator output meets the conditions specified by the CM [2:0] bits and CEN
is set. The flag must be cleared by software. The interrupt may be enabled/disabled by setting/clearing bit 6 of IE.
CEN
Comparator Enable. Set this bit to enable the comparator. Clearing this bit will force the comparator output low and
prevent further events from setting CF. When CEN = 1 the analog input pins, P1.0 and P1.1, have their digital inputs
disabled.
CM [2:0]
Comparator Interrupt Mode
CM2 CM1 CM0 Interrupt Mode
000Negative (Low) level
001Positive edge
010Toggle with debouncing
(1)
011Positive edge with debouncing
(1)
100Negative edge
101Toggle
110Negative edge with debouncing(1)
111Positive (High) level
Comparator Out
Timer 1 Overflow
CF
Start Compare
Start Compare
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AT89LP216
21. Programmable Watchdog Timer
The programmable Watchdog Timer (WDT) protects the system from incorrect execution by trig-
gering a system reset when it times out after the software has failed to feed the timer prior to the
timer overflow. By Default the WDT counts CPU clock cycles. The prescaler bits, PS0, PS1 and
PS2 in SFR WDTCON are used to set the period of the Watchdog Timer from 16K to 2048K
clock cycles. The Timer Prescaler can also be used to lengthen the time-out period (see Table
9-2 on page 13). The WDT is disabled by Reset and during Power-down mode. When the WDT
times out without being serviced, an internal RST pulse is generated to reset the CPU. See
Table 21-1 for the available WDT period selections.
Note: 1. The WDT time-out period is dependent on the system clock frequency.
The Watchdog Timer consists of a 14-bit timer with 7-bit programmable prescaler. Writing the
sequence 1EH/E1H to the WDTRST register enables the timer. When the WDT is enabled, the
WDTEN bit in WDTCON will be set to “1”. To prevent the WDT from generating a reset when if
overflows, the watchdog feed sequence must be written to WDTRST before the end of the time-
out period. To feed the watchdog, two write instructions must be sequentially executed success-
fully. Between the two write instructions, SFR reads are allowed, but writes are not allowed. The
instructions should move 1EH to the WDTRST register and then 1EH to the WDTRST register.
An incorrect feed or enable sequence will cause an immediate watchdog reset. The program
sequence to feed or enable the watchdog timer is as follows:
MOV WDTRST, #01Eh
MOV WDTRST, #0E1h
Table 21-1. Watchdog Timer Time-out Period Selection
WDT Prescaler Bits Period(1)
(Clock Cycles)PS2 PS1 PS0
000 16K
001 32K
010 64K
011 128K
100 256K
101 512K
1 1 0 1024K
1 1 1 2048K
Time-out Period 2PS 14+()
Oscillator Frequency
-------------------------------------------------------TPS 1+()×=
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21.1 Software Reset
A Software Reset of the AT89LP216 is accomplished by writing the software reset sequence
5AH/A5H to the WDTRST SFR. The WDT does not need to be enabled to generate the software
reset. A normal software reset will set the SWRST flag in WDTCON. However, if at any time an
incorrect sequence is written to WDTRST (i.e. anything other than 1EH/E1H or 5AH/A5H), a
software reset will immediately be generated and both the SWRST and WDTOVF flags will be
set. In this manner an intentional software reset may be distinguished from a software error-gen-
erated reset. The program sequence to generate a software reset is as follows:
MOV WDTRST, #05Ah
MOV WDTRST, #0A5h
Table 21-2. WDTCON – Watchdog Control Register
WDTCON Address = A7H Reset Value = 0000 X000B
Not Bit Addressable
PS2 PS1 PS0 WDIDLE – SWRST WDTOVF WDTEN
Bit76543210
Symbol Function
PS2
PS1
PS0
Prescaler bits for the watchdog timer (WDT). When all three bits are cleared to 0, the watchdog timer has a nominal
period of 16K clock cycles. When all three bits are set to 1, the nominal period is 2048K clock cycles.
WDIDLE Disable/enable the Watchdog Timer in IDLE mode. When WDIDLE = 0, WDT continues to count in IDLE mode. When
WDIDLE = 1, WDT freezes while the device is in IDLE mode.
SWRST Software Reset Flag. Set when a software reset is generated by writing the sequence 5AH/A5H to WDTRST. Also set
when an incorrect sequence is written to WDTRST. Must be cleared by software.
WDTOVF Watchdog Overflow Flag. Set when a WDT rest is generated by the WDT timer overflow. Also set when an incorrect
sequence is written to WDTRST. Must be cleared by software.
WDTEN Watchdog Enable Flag. This bit is READ-ONLY and reflects the status of the WDT (whether it is running or not). The
WDT is disabled after any reset and must be re-enabled by writing 1EH/E1H to WDTRST
Table 21-3. WDTRST – Watchdog Reset Register
WDTCON Address = A6H (Write-Only)
Not Bit Addressable
––––––––
Bit76543210
The WDT is enabled by writing the sequence 1EH/E1H to the WDTRST SFR. The current status may be checked by reading
the WDTEN bit in WDTCON. To prevent the WDT from resetting the device, the same sequence 1EH/E1H must be written to
WDTRST before the time-out interval expires. A software reset is generated by writing the sequence 5AH/A5H to WDTRST.
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22. Instruction Set Summary
The AT89LP216 is fully binary compatible with the MCS-51 instruction set. The difference
between the AT89LP216 and the standard 8051 is the number of cycles required to execute an
instruction. Instructions in the AT89LP216 may take 1, 2, 3 or 4 clock cycles to complete. The
execution times of most instructions may be computed using Table 22-1.
Table 22-1. Instruction Execution Times and Exceptions
Generic Instruction Types Cycle Count Formula
Most arithmetic, logical, bit and transfer instructions # bytes
Branches and Calls # bytes + 1
Single Byte Indirect (i.e. ADD A, @Ri, etc.) 2
RET, RETI 4
MOVC 3
MOVX 4
MUL 2
DIV 4
INC DPTR 2
Arithmetic Bytes
Clock Cycles
Hex Code8051 AT89LP
ADD A, Rn 1 12 1 28-2F
ADD A, direct 2 12 2 25
ADD A, @Ri 1 12 2 26-27
ADD A, #data 2 12 2 24
ADDC A, Rn 1 12 1 38-3F
ADDC A, direct 2 12 2 35
ADDC A, @Ri 1 12 2 36-37
ADDC A, #data 2 12 2 34
SUBB A, Rn 1 12 1 98-9F
SUBB A, direct 2 12 2 95
SUBB A, @Ri 1 12 2 96-97
SUBB A, #data 2 12 2 94
INC Rn 1 12 1 08-0F
INC direct 2 12 2 05
INC @Ri 1 12 2 06-07
INC A 2 12 2 04
DEC Rn 1 12 1 18-1F
DEC direct 2 12 2 15
DEC @Ri 1 12 2 16-17
DEC A 2 12 2 14
INC DPTR 1 24 2 A3
MUL AB 1 48 2 A4
DIV AB 1 48 4 84
DA A 1 12 1 D4
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Logical Bytes
Clock Cycles
Hex Code8051 AT89LP
CLR A 1 12 1 E4
CPL A 1 12 1 F4
ANL A, Rn 1 12 1 58-5F
ANL A, direct 2 12 2 55
ANL A, @Ri 1 12 2 56-57
ANL A, #data 2 12 2 54
ANL direct, A 2 12 2 52
ANL direct, #data 3 24 3 53
ORL A, Rn 1 12 1 48-4F
ORL A, direct 2 12 2 45
ORL A, @Ri 1 12 2 46-47
ORL A, #data 2 12 2 44
ORL direct, A 2 12 2 42
ORL direct, #data 3 24 3 43
XRL A, Rn 1 12 1 68-6F
XRL A, direct 2 12 2 65
XRL A, @Ri 1 12 2 66-67
XRL A, #data 2 12 2 64
XRL direct, A 2 12 2 62
XRL direct, #data 3 24 3 63
RL A 1 12 1 23
RLC A 1 12 1 33
RR A 1 12 1 03
RRC A 1 12 1 13
SWAP A 1 12 1 C4
Table 22-1. Instruction Execution Times and Exceptions (Continued)
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AT89LP216
Data Transfer Bytes
Clock Cycles
Hex Code8051 AT89LP
MOV A, Rn 1 12 1 E8-EF
MOV A, direct 2 12 2 E5
MOV A, @Ri 1 12 2 E6-E7
MOV A, #data 2 12 2 74
MOV Rn, A 1 12 1 F8-FF
MOV Rn, direct 2 24 2 A8-AF
MOV Rn, #data 2 12 2 78-7F
MOV direct, A 2 12 2 F5
MOV direct, Rn 2 24 2 88-8F
MOV direct, direct 3 24 3 85
MOV direct, @Ri 2 24 2 86-87
MOV direct, #data 3 24 3 75
MOV @Ri, A 1 12 1 F6-F7
MOV @Ri, direct 2 24 2 A6-A7
MOV @Ri, #data 2 12 2 76-77
MOV DPTR, #data16 3 24 3 90
MOVC A, @A+DPTR 1 24 3 93
MOVC A, @A+PC 1 24 3 83
MOVX A, @Ri 1 24 4 E2-E3
MOVX A, @DPTR 1 24 4 E0
MOVX @Ri, A 1 24 4 F2-F3
MOVX @DPTR, A 1 24 4 F0
PUSH direct 2 24 2 C0
POP direct 2 24 2 D0
XCH A, Rn 1 12 1 C8-CF
XCH A, direct 2 12 2 C5
XCH A, @Ri 1 12 2 C6-C7
XCHD A, @Ri 1 12 2 D6-D7
Table 22-1. Instruction Execution Times and Exceptions (Continued)
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3621E–MICRO–11/10
AT89LP216
Note: 1. This escaped instruction is an extension to the instruction set.
Bit Operations Bytes
Clock Cycles
Hex Code8051 AT89LP
CLR C 1 12 1 C3
CLR bit 2 12 2 C2
SETB C 1 12 1 D3
SETB bit 2 12 2 D2
CPL C 1 12 1 B3
CPL bit 2 12 2 B2
ANL C, bit 2 24 2 82
ANL C, bit 2 24 2 B0
ORL C, bit 2 24 2 72
ORL C, /bit 2 24 2 A0
MOV C, bit 2 12 2 A2
MOV bit, C 2 24 2 92
Branching Bytes
Clock Cycles
Hex Code8051 AT89LP
JC rel 2 24 3 40
JNC rel 2 24 3 50
JB bit, rel 3 24 4 20
JNB bit, rel 3 24 4 30
JBC bit, rel 3 24 4 10
JZ rel 2 24 3 60
JNZ rel 2 24 3 70
SJMP rel 2 24 3 80
ACALL addr11 2 24 3 11,31,51,71,91,
B1,D1,F1
LCALL addr16 3 24 4 12
RET 1 24 4 22
RETI 1 24 4 32
AJMP addr11 2 24 3 01,21,41,61,81,
A1,C1,E1
LJMP addr16 3 24 4 02
JMP @A+DPTR 1 24 2 73
JMP @A+PC(1) 2– 3A573
CJNE A, direct, rel 3 24 4 B5
CJNE A, #data, rel 3 24 4 B4
CJNE Rn, #data, rel 3 24 4 B8-BF
CJNE @Ri, #data, rel 3 24 4 B6-B7
DJNZ Rn, rel 2 24 3 D8-DF
DJNZ direct, rel 3 24 4 D5
NOP 1 12 1 00
BREAK(1) 2– 2A500
Table 22-1. Instruction Execution Times and Exceptions (Continued)
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AT89LP216
23. On-chip Debug System
The AT89LP216 On-chip Debug (OCD) System uses a two-wire serial interface to control pro-
gram flow; read, modify, and write the system state; and program the nonvolatile memory. The
OCD System has the following features:
• Complete program flow control
• Read-modify-write access to all internal SFRs and data memories
• Four hardware program address breakpoints
• Unlimited program software breakpoints using BREAK instruction
• Break on stack overflow/underflow
• Break on Watchdog overflow
• Non-intrusive operation
• Programming of nonvolatile memory
23.1 Physical Interface
The On-chip Debug System uses a two-wire synchronous serial interface to establish communi-
cation between the target device and the controlling emulator system. The OCD interface is
controlled by two User Fuses. OCD is enabled by clearing the OCD Enable Fuse. When OCD is
enabled, the RST port pin is configured as an input for the Debug Clock (DCL). Either the XTAL1
or XTAL2 pin is configured as a bi-directional data line for the Debug Data (DDA) depending on
the clock source selected. If the External Clock is selected, XTAL2 is configured as DDA. If the
Internal RC Oscillator is selected, XTAL1 is configured as DDA. The OCD device connections
are shown in Figure 23-1. The OCD Interface Select User Fuse should always be set for the fast
two-wire interface (FTWI). It is the duty of the user to program these fuses to the correct settings
before using the device in their debug system (see “User Configuration Fuses” on page 71).
Figure 23-1. AT89LP216 On-chip Debug Connections
When designing a system where On-chip Debug will be used, the following observations must
be considered for correct operation:
• P1.3/RST cannot be connected directly to VCC and any external capacitors connect to RST
must be removed.
• All external reset sources must be removed.
• The quartz crystal and any capacitors on XTAL1 or XTAL2 must be removed and an external
clock signal must be driven on XTAL1 if the user does not wish to use the internal RC
oscillator. Some emulator systems may provide a user-configurable clock for this purpose.
CLK = Internal RC
VCC
XTAL1
P1.3/RST
GND
DCL
DDA
CLK = External Clock
VCC
XTAL2
P1.3/RST
GND
DCL
DDAXTAL1CLK
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AT89LP216
23.2 Software Breakpoints
The AT89LP216 microcontroller includes a BREAK instruction for implementing program mem-
ory breakpoints in software. A software breakpoint can be inserted manually by placing the
BREAK instruction in the program code. Some emulator systems may allow for automatic inser-
tion/deletion of software breakpoints. The Flash memory must be re-programmed each time a
software breakpoint is changed. Frequent insertions/deletions of software breakpoints will
reduce the data retention of the nonvolatile memory. Devices used for debugging purposes
should not be shipped to end customers. The BREAK instruction is treated as a two-cycle NOP
when OCD is disabled.
23.3 Limitations of On-chip Debug
The AT89LP216 is a low-cost, low-pincount yet fully-featured microcontroller that multiplexes
several functions on its limited I/O pins. Some device functionality must be sacrificed to provide
resources for On-chip Debugging. The On-chip Debug System has the following limitations:
• The Debug Clock pin (DCL) is physically located on that same pin as Port Pin P1.3 and the
External Reset (RST). Therefore, neither P1.3 nor an external reset source may be emulated
when OCD is enabled.
• The Debug Data pin (DDA) is physically located on either the XTAL1/P3.2 or XTAL2/P3.3 pin.
The crystal oscillator is therefore not supported during debug. The user must select either the
Internal RC Oscillator or the External Clock source to provide the system clock. Devices
fused for the crystal oscillator will default to external clock mode when OCD is enabled.
• When using the Internal RC Oscillator during debug, DDA is located on the XTAL1/P3.2 pin.
The INT0 function cannot be emulated in this mode.
• When using the External Clock during debug, DDA is located on the XTAL2/P3.3 pin and the
system clock drives XTAL1/P3.2. The INT0, INT1 and CLKOUT functions cannot be emulated
in this mode.
• The AT89LP216 does not support In-Application Programming and therefore the device must
be reset before changing the program code during debugging. This includes the
insertion/deletion of software breakpoints.
• When using the watchdog to generate a break, the state of the watchdog will not be reset. An
OCD reset command should be sent to the device prior to resuming normal execution to
ensure correct watchdog behavior.
24. Programming the Flash Memory
The Atmel AT89LP216 microcontroller features 2KB of on-chip In-System Programmable Flash
program memory. In-System Programming (ISP) allows programming and reprogramming of the
microcontroller positioned inside the end system. Using a simple 4-wire SPI interface, the In-
System programmer communicates serially with the AT89LP216 microcontroller, reprogram-
ming all nonvolatile memories on the chip. In-System programming eliminates the need for
physical removal of the chips from the system. This will save time and money, both during devel-
opment in the lab, and when updating the software or parameters in the field. The ISP interface
of the AT89LP216 includes the following features:
• Four Wire SPI Programming Interface
• Active-low Reset Entry into Programming
• Slave Select allows multiple devices on same interface
• User Signature Array
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AT89LP216
• Flexible Page Programming
• Row Erase Capability
• Page Write with Auto-Erase Commands
• Programming Status Register
For more detailed information on In-System Programming, refer to the Application Note entitled
“AT89LP In-System Programming Specification”.
24.1 Physical Interface
In-System Programming utilizes the Serial Peripheral Interface (SPI) pins of an AT89LP216
microcontroller. The SPI is a full duplex synchronous serial interface consisting of four wires:
Serial Clock (SCK), Master-In/Slave-out (MISO), Master-out/Slave-in (MOSI), and an active-low
Slave Select (SS). When programming an AT89LP216 device, the programmer always operates
as the SPI master, and the target system always operates as the SPI slave. To enter or remain
in In-System Programming mode the device’s reset line (RST) must be held active (low). With
the addition of VCC and GND, an AT89LP216 microcontroller can be programmed with a mini-
mum of seven connections as shown in Figure 24-1.
Figure 24-1. In-System Programming Device Connections
The In-System Programming Interface is the only means of externally programming the
AT89LP216 microcontroller. The ISP Interface can be used to program the device both in-sys-
tem and in a stand-alone serial programmer. The ISP Interface does not require any clock other
than SCK and is not limited by the system clock frequency. During In-System programming the
system clock source of the target device can operate normally.
When designing a system where In-System Programming will be used, the following observa-
tions must be considered for correct operation:
• The ISP interface uses the SPI clock mode 0 (CPOL = 0,CPHA = 0) exclusively with a
maximum frequency of 5 MHz.
• The AT89LP216 will enter programming mode only when its reset line (RST) is active (low).
To simplify this operation, it is recommended that the target reset can be controlled by the In-
System programmer. To avoid problems, the In-System programmer should be able to keep
the entire target system reset for the duration of the programming cycle. The target system
should never attempt to drive the four SPI lines while reset is active.
AT89LP216
VCC
P1.3/RST
P1.7/SCK
P1.5/MOSI
GND
Serial Clock
Serial In
RST
P1.4/SS
P1.6/MISOSerial Out
SS
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AT89LP216
•The RST input may be disabled to gain an extra I/O pin. In these cases the RST pin will
always function as a reset during power up. To enter programming the RST pin must be
driven low prior to the end of Power-On Reset (POR). After POR has completed the device
will remain in ISP mode until RST is brought high. Once the initial ISP session has ended, the
power to the target device must be cycled OFF and ON to enter another session.
•The SS
pin should not be left floating during reset if ISP is enabled.
• The ISP Enable Fuse must be set to allow programming during any reset period. If the ISP
Fuse is disabled, ISP may only be entered at POR.
24.2 Memory Organization
The AT89LP216 offers 2K bytes of In-System Programmable (ISP) nonvolatile Flash code mem-
ory. In addition, the device contains a 64-byte User Signature Array and a 32-byte read-only
Atmel Signature Array. The memory organization is shown in Table 24-1 and Figure 24-2. The
memory is divided into pages of 32 bytes each. A single read or write command may only
access a single page in the memory. Each memory type resides in its own address space and is
accessed by commands specific to that memory. However, all memory types share the same
page size.
User configuration fuses are mapped as a row in the memory, with each byte representing one
fuse. From a programming standpoint, fuses are treated the same as normal code bytes except
they are not affected by Chip Erase. Fuses can be enabled at any time by writing 00h to the
appropriate locations in the fuse row. However, to disable a fuse, i.e. set it to FFh, the entire
fuse row must be erased and then reprogrammed. The programmer should read the state of all
the fuses into a temporary location, modify those fuses which need to be disabled, then issue a
Fuse Write with Auto-Erase command using the temporary data. Lock bits are treated in a simi-
lar manner to fuses except they may only be erased (unlocked) by Chip Erase.
Figure 24-2. AT89LP216 Memory Organization
Table 24-1. Code Memory Sizes
Device # Code Size Page Size # Pages Address Range
AT89LP216 2K bytes 32 bytes 64 0000H - 07FFH
Page 0
Page 1
Page 63
Page 62
Page 0
Page 0
Page 0
User Fuse Row
User Signature Array
Atmel Signature Array
Code Memory
Page 1
00 1F
0000
07FF
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AT89LP216
24.3 Command Format
Programming commands consist of an opcode byte, two address bytes, and zero or more data
bytes. In addition, all command packets must start with a two-byte preamble of AAH and 55H.
The preamble increases the noise immunity of the programming interface by making it more dif-
ficult to issue unintentional commands. Figure 24-3 on page 68 shows a simplified flow chart of
a command sequence.
A sample command packet is shown in Figure 24-4 on page 68. The SS pin defines the packet
frame. SS must be brought low before the first byte in a command is sent and brought back high
after the final byte in the command has been sent. The command is not complete until SS
returns high. Command bytes are issued serially on MOSI. Data output bytes are received seri-
ally on MISO. Packets of variable length are supported by returning SS high when the final
required byte has been transmitted. In some cases command bytes have a don’t care value.
Don’t care bytes in the middle of a packet must be transmitted. Don’t care bytes at the end of a
packet may be ignored.
Page oriented instructions always include a full 16-bit address. The higher order bits select the
page and the lower order bits select the byte within that page. The AT89LP216 allocates 5 bits
for byte address and 6 bits for page address. The page to be accessed is always fixed by the
page address as transmitted. The byte address specifies the starting address for the first data
byte. After each data byte has been transmitted, the byte address is incremented to point to the
next data byte. This allows a page command to linearly sweep the bytes within a page. If the
byte address is incremented past the last byte in the page, the byte address will roll over to the
first byte in the same page. While loading bytes into the page buffer, overwriting previously
loaded bytes will result in data corruption.
For a summary of available commands, see Table 24-2 on page 69.
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AT89LP216
Figure 24-3. Command Sequence Flow Chart
Figure 24-4. ISP Command Packet
Input Preamble 2
(55h)
Input Opcode
Input Address
High Byte
Input Address
Low Byte
Input/Output
Data Address +1
Input Preamble 1
(AAh)
70654321 7 0654321 7 0654321 7 0654321
70654321
SS
SCK
MOSI
MISO
Preamble 2 Opcode Address High Address Low Data In
Data Out
XXXX
Preamble 1
X
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AT89LP216
Notes: 1. Program Enable must be the first command issued after entering into programming mode.
2. Any number of Data bytes from 1 to 32 may be written/read. The internal address is incremented between each byte.
3. Each byte address selects one fuse or lock bit. Data bytes must be 00h or FFh.
4. See Table 24-5 on page 71 for Fuse definitions.
5. See Table 24-4 on page 70 for Lock Bit definitions.
6. Atmel Signature Bytes:
7. Symbol Key:
Table 24-2. Programming Command Summary
Command Opcode Addr High Addr Low Data 0 Data n
Program Enable(1) 1010 1100 0101 0011 – – –
Chip Erase 10001010––––
Read Status 0110 0000 xxxx xxxx xxxx xxxx Status Out
Load Page Buffer(2) 0101 0001 xxxx xxxx xxxb bbbb DataIn 0 ... DataIn n
Write Code Page(2) 0101 0000 xxxx xaaa aaab bbbb DataIn 0 ... DataIn n
Write Code Page with Auto-Erase(2) 0111 0000 xxxx xaaa aaab bbbb DataIn 0 ... DataIn n
Read Code Page(2) 0011 0000 xxxx xaaa aaab bbbb DataOut 0 ... DataOut n
Write User Fuses(2)(3)(4) 1110 0001 0000 0000 000b bbbb DataIn 0 ... DataIn n
Write User Fuses with Auto-Erase(2)(3)(4) 1111 0001 0000 0000 000b bbbb DataIn 0 ... DataIn n
Read User Fuses(2)(3)(4) 0110 0001 0000 0000 000b bbbb DataOut 0 ... DataOut n
Write Lock Bits(2)(3)(5) 1110 0100 0000 0000 000b bbbb DataIn 0 ... DataIn n
Read Lock Bits(2)(3)(5) 0110 0100 0000 0000 000b bbbb DataOut 0 ... DataOut n
Write User Signature Page(2) 0101 0010 xxxx xxxx xaab bbbb DataIn 0 ... DataIn n
Write User Signature Page with Auto-Erase(2) 0111 0010 xxxx xxxx xaab bbbb DataIn 0 ... DataIn n
Read User Signature Page(2) 0011 0010 xxxx xxxx xaab bbbb DataOut 0 ... DataOut n
Read Atmel Signature Page(2)(6) 0011 1000 xxxx xxxx xxxb bbbb DataOut 0 ... DataOut n
AT89LP216: Address 00H = 1EH
01H = 29H
02H = FFH
a: Page Address Bit
b: Byte Address Bit
x: Don’t Care Bit
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24.4 Status Register
The current state of the memory may be accessed by reading the status register. The status reg-
ister is shown in Table 24-3.
24.5 DATA Polling
The AT89LP216 implements DATA polling to indicate the end of a programming cycle. While the
device is busy, any attempted read of the last byte written will return the data byte with the MSB
complemented. Once the programming cycle has completed, the true value will be accessible.
During Erase the data is assumed to be FFH and DATA polling will return 7FH. When writing
multiple bytes in a page, the DATA value will be the last data byte loaded before programming
begins, not the written byte with the highest physical address within the page.
24.6 Flash Security
The AT89LP216 provides two Lock Bits for Flash Code Memory security. Lock bits can be left
unprogrammed (FFh) or programmed (00h) to obtain the protection levels listed in Table 24-4.
Lock bits can only be erased (set to FFh) by Chip Erase. Lock bit mode 2 disables programming
of all memory spaces, including the User Signature Array and User Configuration Fuses. User
fuses must be programmed before enabling Lock bit mode 2 or 3. Lock bit mode 3 implemented
mode 2 and also blocks reads from the code memory; however, reads of the User Signature
Array, Atmel Signature Array, and User Configuration Fuses are still allowed.
Table 24-3. Status Register
– – – – LOAD SUCCESS WRTINH BUSY
Bit76543210
Symbol Function
LOAD Load flag. Cleared low by the load page buffer command and set high by the next memory write. This flag signals that
the page buffer was previously loaded with data by the load page buffer command.
SUCCESS Success flag. Cleared low at the start of a programming cycle and will only be set high if the programming cycle
completes without interruption from the brownout detector.
WRTINH
Write Inhibit flag. Cleared low by the brownout detector (BOD) whenever programming is inhibited due to VCC falling
below the minimum required programming voltage. If a BOD episode occurs during programming, the SUCCESS flag
will remain low after the cycle is complete. WRTINH low also forces BUSY low.
BUSY Busy flag. Cleared low whenever the memory is busy programming or if write is currently inhibited.
Table 24-4. Lock Bit Protection Modes
Program Lock Bits (by address)
Mode 00h 01h Protection Mode
1 FFh FFh No program lock features
2 00h FFh Further programming of the Flash is disabled
3 00h 00h Further programming of the Flash is disabled and verify
(read) is also disabled; OCD is disabled
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24.7 User Configuration Fuses
The AT89LP216 includes 19 user fuses for configuration of the device. Each fuse is accessed at
a separate address in the User Fuse Row as listed in Table 24-5. Fuses are cleared by program-
ming 00h to their locations. Programming FFh to fuse location will cause that fuse to maintain its
previous state. To set a fuse (set to FFh) the fuse row must be erased and then reprogrammed
using the Fuse Write with Auto-erase command. The default state for all fuses is FFh.
Notes: 1. The default state for all fuses is FFh.
2. Changes to these fuses will only take effect after a device POR.
3. Changes to these fuses will only take effect after the ISP session terminates by bringing RST high.
4. AIN0 (P1.0) and AIN1 (P1.1) always reset to input-only mode. SS (P1.4) always resets to quasi-bidirectional mode.
Table 24-5. User Configuration Fuse Definitions
Address Fuse Name Description
00 – 01h Clock Source – CS[0:1](2)
Selects source for the system clock:
CS1 CS0 Selected Source
00h 00h Crystal Oscillator (XTAL)
00h FFh Reserved
FFh 00h External Clock on XTAL1 (XCLK)
FFh FFh Internal RC Oscillator (IRC)
02 – 03h Start-up Time – SUT[0:1]
Selects time-out delay for the POR/BOD/PWD wake-up period:
SUT1 SUT0 Selected Time-out
00h 00h 1 ms (XTAL); 16 µs (XCLK/IRC)
00h FFh 2 ms (XTAL); 512 µs (XCLK/IRC)
FFh 00h 4ms (XTAL); 1ms (XCLK/IRC)
FFh FFh 16 ms (XTAL); 4 ms (XCLK/IRC)
04h Reset Pin Enable(3) FFh: RST pin functions as reset
00h: RST pin functions as general purpose I/O
05h Brown-out Detector Enable FFh: Brown-out Detector Enabled
00h: Brown-out Detector Disabled
06h On-chip Debug Enable FFh: On-chip Debug Disabled
00h: On-chip Debug Enabled
07h ISP Enable(3) FFh: In-System Programming Enabled
00h: In-System Programming Disabled (Enabled at POR only)
08 – 0FH RC Oscillator Frequency
Adjustment [0:7]
Adjusts the frequency of the internal RC oscillator. A copy of the 8MHz factory
setting is stored at location 0008h of the Atmel Signature.
10H User Signature Programming FFh: Programming of User Signature Disabled
00h: Programming of User Signature Enabled
11H Tristate Ports(4) FFh: I/O Ports start in input-only mode (tristated) after reset
00h: I/O Ports start in quasi-bidirectional mode after reset
12H OCD Interface Select FFh: Fast two-wire interface
00h: Do not use
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24.8 Programming Interface Timing
This section details general system timing sequences and constraints for entering or exiting In-
System Programming as well as parameters related to the Serial Peripheral Interface during
ISP. The general timing parameters for the following waveform figures are listed in Section
24.8.6 “Timing Parameters” on page 75.
24.8.1 Power-up Sequence
Execute this sequence to enter programming mode immediately after power-up. In the RST pin
is disabled or if the ISP Fuse is disabled, this is the only method to enter programming (see Sec-
tion 10.3 “External Reset” on page 15).
1. Apply power between VCC and GND pins. RST should remain low.
2. Wait at least tPWRUP
. and drive SS high.
3. Wait at least tSUT for the internal Power-on Reset to complete. The value of tSUT will
depend on the current settings of the device.
4. Start programming session.
Figure 24-5. Serial Programming Power-up Sequence
24.8.2 Power-down Sequence
Execute this sequence to power-down the device after programming.
1. Drive SCK low.
2. Wait at least tSSD and bring SS high.
3. Tristate MOSI.
4. Wait at least tSSZ and then tristate SS and SCK.
5. Wait no more than tPWRDN and power off VCC.
Figure 24-6. Serial Programming Power-down Sequence
V
CC
RST
SS
SCK
HIGH ZMISO
HIGH ZMOSI
t
PWRUP
t
POR
+ t
SUT
t
ZSS
V
CC
RST
SS
SCK
HIGH ZMISO
HIGH ZMOSI
t
PWRDN
t
SSD
t
SSZ
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24.8.3 ISP Start Sequence
Execute this sequence to exit CPU execution mode and enter ISP mode when the device has
passed Power-on Reset and is already operational.
1. Drive RST low.
2. Drive SS high.
3. Wait tRLZ + tSTL.
4. Start programming session.
Figure 24-7. In-System Programming (ISP) Start Sequence
24.8.4 ISP Exit Sequence
Execute this sequence to exit ISP mode and resume CPU execution mode.
1. Drive SCK low.
1. Wait at least tSSD and drive SS high.
2. Tristate MOSI.
3. Wait at least tSSZ and bring RST high.
4. Tristate SCK.
5. Wait tRHZ and tristate SS.
Figure 24-8. In-System Programming (ISP) Exit Sequence
Note: The waveforms on this page are not to scale.
t
STL
V
CC
RST
SS
SCK
HIGH ZMOSI
HIGH ZMISO
XTAL1
t
RLZ
t
ZSS
t
SSE
V
CC
RST
SS
SCK
HIGH ZMOSI
HIGH ZMISO
XTAL1
t
SSZ
t
SSD
t
RHZ
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24.8.5 Serial Peripheral Interface
The Serial Peripheral Interface (SPI) is a byte-oriented full duplex synchronous serial communi-
cation channel. During In-System programming the programmer always acts as the SPI master
and the target device always acts as the SPI slave. The target device receives serial data on
MOSI and outputs serial data on MISO. The Programming Interface implements a standard
SPI Port with a fixed data order and For In-System programming, bytes are transferred MSB first
as shown in Figure 24-9. The SCK phase and polarity follow SPI clock mode 0 (CPOL = 0,
CPHA = 0) where bits are sampled on the rising edge of SCK and output on the falling edge of
SCK. For more detailed timing information see Figure 24-10.
Figure 24-9. ISP Byte Sequence
Figure 24-10. Serial Programming Interface Timing
7
7
6
6
5
5
4
4
3
3
2
2
1
1
0
0
MOSI
MISO
SCK
Data Sampled
tSR
tSSE
tSLSH
tSOV
tSF
tSOX
tSSD
tSCK
tSHSL
tSOE tSOH
tSIH
tSIS
SS
SCK
MISO
MOSI
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24.8.6 Timing Parameters
The timing parameters for Figure 24-5, Figure 24-6, Figure 24-7, Figure 24-8, and Figure 24-10
are shown in Table .
Note: 1. tSCK is independent of tCLCL.
Table 24-6. Programming Interface Timing Parameters
Symbol Parameter Min Max Units
tCLCL System Clock Cycle Time 0 60 ns
tPWRUP Power On to SS High Time 10 µs
tPOR Power-on Reset Time 100 µs
tPWRDN SS Tristate to Power Off 1 µs
tRLZ RST Low to I/O Tristate tCLCL 2 tCLCL ns
tSTL RST Low Settling Time 100 ns
tRHZ RST High to SS Tristate 0 2 tCLCL ns
tSCK Serial Clock Cycle Time 200(1) ns
tSHSL Clock High Time 75 ns
tSLSH Clock Low Time 50 ns
tSR Rise Time 25 ns
tSF Fall Time 25 ns
tSIS Serial Input Setup Time 10 ns
tSIH Serial Input Hold Time 10 ns
tSOH Serial Output Hold Time 10 ns
tSOV Serial Output Valid Time 35 ns
tSOE Output Enable Time 10 ns
tSOX Output Disable Time 25 ns
tSSE SS Enable Lead Time tSLSH ns
tSSD SS Disable Lag Time tSLSH ns
tZSS SCK Setup to SS Low 25 ns
tSSZ SCK Hold after SS High 25 ns
tWR Write Cycle Time 2.5 ms
tAWRWrite Cycle with Auto-Erase Time 5 ms
tERS Chip Erase Cycle Time 7.5 ms
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25. Electrical Characteristics
Notes: 1. Under steady state (non-transient) conditions, IOL must be externally limited as follows:
Maximum IOL per port pin: 10 mA
Maximum total IOL for all output pins: 15 mA
If IOL exceeds the test condition, VOL may exceed the related specification. Pins are not guaranteed to sink current greater
than the listed test conditions.
2. VOH1 levels are listed for DC operation. Under AC conditions a boost circuit provides additional source current.
3. Minimum VCC for Power-down is 2V.
25.1 Absolute Maximum Ratings*
Operating Temperature ................................... -40°C to +85°C *NOTICE: Stresses beyond those listed under “Absolute
Maximum Ratings” may cause permanent dam-
age to the device. This is a stress rating only and
functional operation of the device at these or any
other conditions beyond those indicated in the
operational sections of this specification is not
implied. Exposure to absolute maximum rating
conditions for extended periods may affect
device reliability.
Storage Temperature ..................................... -65°C to +150°C
Voltage on Any Pin with Respect to Ground......-0.7V to +5.5V
Maximum Operating Voltage ............................................ 5.5V
DC Output Current...................................................... 15.0 mA
25.2 DC Characteristics
TA = -40°C to 85°C, VCC = 2.4V to 5.5V (unless otherwise noted)
Symbol Parameter Condition Min Max Units
VIL Input Low-voltage -0.5 0.3 VCC V
VIH Input High-voltage 0.7 VCC VCC + 0.5 V
VOL Output Low-voltage(1) (Ports 1, 3) IOL = 10 mA, TA = 85°C 0.5 V
VOH
Output High-voltage (Ports 1, 3)
With Weak Pull-ups Enabled
IOH = -80 µA, VCC = 5V ± 10% 2.4 V
IOH = -25 µA 0.7 VCC V
IOH = -10 µA 0.9 VCC V
VOH1
Output High-voltage (Ports 1, 3)
With Strong Pull-ups Enabled(2)
IOH = -2 mA, VCC = 5V ± 10% 2.4 V
IOH = -500 µA, VCC = 5V ± 10% 0.6 VCC V
IOH = -100 µA 0.6 VCC V
IIL
Logic 0 Input Current
(Quasi-Bidirectional Mode) VIN = 0.45V -50 µA
ITL
Logic 1 to 0 Transition Current
(Quasi-Bidirectional Mode) VIN = 2V, VCC = 5V ± 10% -300 µA
ILI
Input Leakage Current
(Input-Only Mode) 0 < VIN < VCC ±10 µA
VOS Comparator Input Offset Voltage VCC = 5V 20 mV
VCM
Comparator Input Common
Mode Voltage 0V
CC V
RRST Reset Pull-up Resistor 50 150 kΩ
CIO Pin Capacitance Test Freq. = 1 MHz, TA = 25°C 10 pF
ICC
Power Supply Current Active Mode, 12 MHz, VCC = 5V/3V 10/6 mA
Idle Mode, 12 MHz, VCC = 5./3V 3/1.5 mA
Power-down Mode(3) VCC = 5V, P1.0 & P1.1 = 0V or VCC 5µA
VCC = 3V, P1.0 & P1.1 = 0V or VCC 2µA
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25.3 Typical Characteristics
The following charts show typical behavior. These figures are not tested during manufacturing.
All current consumption measurements are performed with all I/O pins configured as quasi-bidi-
rectional (with internal pull-ups). A square wave generator with rail-to-rail output is used as an
external clock source for consumption versus frequency measurements.
25.3.1 Supply Current (Internal Oscillator)
Figure 25-1. Active Supply Current vs. VCC ( 8MHz Internal Oscillator)
Figure 25-2. Idle Supply Current vs. Vcc (8 MHz Internal Oscillator)
2.0 2.5 3.0 3.5 4.0 4.5 5.0 5.5
0
1
2
3
4
5
6
7 85C
-40C
25C
Vcc (V)
Icc (mA)
2.0 2.5 3.0 3.5 4.0 4.5 5.0 5.5
0.0
0.5
1.0
1.5
2.0
2.5
3.0
85C
-40C
25C
Vcc (V)
Icc (mA)
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25.3.2 Supply Current (External Clock)
Figure 25-3. Active Supply Current vs. Frequency
Figure 25-4. Idle Supply Current vs. Frequency
0 5 10 15 20 25
0
2
4
6
8
10
12
14
16 5.5V
5.0V
4.5V
3.6V
3.0V
2.4V
Frequency (MHz)
Icc (mA)
0 5 10 15 20 25
0
1
2
3
4
5
6
5.5V
5.0V
4.5V
3.3V
2.7V
2.4V
Frequency (MHz)
Icc (mA)
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25.3.3 Internal Oscillator Frequency
Figure 25-5. Internal Oscillator Frequency vs. VCC
Note: The data in this table was characterized on factory calibrated devices. It is not tested during manufacturing and is provided for
reference only. Devices may need to be recalibrated to target different operating conditions than the single-point factory
calibration.
2.0 2.5 3.0 3.5 4.0 4.5 5.0 5.5
7.7
7.8
7.9
8.0
8.1
8.2
8.3
8.4
-40C
0C
25C
70C
85C
Vcc (V)
Frequency (MHz)
Table 25-1. Typical Internal Oscillator Behavior
Symbol Parameter Condition Min Max Units
DfIRC
Relative Frequency Error
(MAX–MIN) / (MAX+MIN)
TA = -40–85°C; VCC = 2.4–5.5V ±4 %
TA = -40–85°C; VCC = 4.5–5.5V ±3 %
TA = -40–85°C; VCC = 2.4–3.6V ±3 %
TA = 0–70°C; VCC = 2.4–5.5V ±3 %
TA = 0–70°C; VCC = 4.5–5.5V ±2 %
TA = 0–70°C; VCC = 2.4–3.6V ±2 %
fIRC
Frequency
(Calibrated at 25°C; 5V)
TA = -40–85°C; VCC = 2.4–5.5V 7.8 8.4 MHz
TA = -40–85°C; VCC = 4.5–5.5V 7.8 8.2 MHz
TA = -40–85°C; VCC = 2.4–3.6V 8.0 8.4 MHz
TA = 0–70°C; VCC = 2.4–5.5V 7.8 8.3 MHz
TA = 0–70°C; VCC = 4.5–5.5V 7.8 8.1 MHz
TA = 0–70°C; VCC = 2.4–3.6V 8.0 8.3 MHz
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25.3.4 Quasi-Bidirectional Output
Figure 25-6. Quasi-Bidirectional Output I-V Characteristic at 5V
Figure 25-7. Quasi-Bidirectional Output I-V Characteristic at 3V
2.0 2.5 3.0 3.5 4.0 4.5 5.0
-100
-80
-60
-40
-20
0 85C
-40C
25C
VOH (V)
IOH (μA)
0.0 0.5 1.0 1.5 2.0 2.5 3.0
-80
-70
-60
-50
-40
-30
-20
-10
85C
-40C
25C
VOH (V)
IOH (μA)
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25.3.5 Push-Pull Output
Figure 25-8. Push-Pull Output I-V Characteristic at 5V
Figure 25-9. Push-Pull Output I-V Characteristic at 3V
Note: Under DC operating conditions the Push-Pull Outputs exhibit reduced VOH levels at higher temper-
atures due to the 5V tolerant port structure. Under AC conditions a boost circuit provides
additional source current. If additional DC source current is required, or if VOH is too low, external
pull-ups may be needed. DC conditions are most likely to exist when the device enters Power-
down mode.
0 1 2 3 4 5
-12
-10
-8
-6
-4
-2
0 85C
-40C
25C
VOH1 (V)
IOH1 (mA)
0.0 0.5 1.0 1.5 2.0 2.5 3.0
-12
-10
-8
-6
-4
-2
0 85C
-40C
25C
VOH1 (V)
IOH1 (mA)
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25.3.6 Crystal Oscillator
Figure 25-10. Quartz Crystal Input at 5V
Figure 25-11. Ceramic Resonator Input at 5V
0 5 10 15 20 25
0
1
2
3
4
5C2=10pF
C2=5pF
C2=0pF
Frequency (MHz)
XTAL1 Amplitude (V)
Oscillator Amplitude vs. Frequency
Quartz Crystal with R1 = 4MΩ
0 5 10 15 20 25
0
1
2
3
4
5
6C2=10pF
C2=5pF
C2=0pF
Frequency (MHz)
XTAL1 Amplitude (V)
Oscillator Amplitude vs. Frequency
Ceramic Resonator with R1 = 4MΩ
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25.4 Clock Characteristics
Figure 25-12. External Clock Drive Waveform
Table 25-2. External Clock Parameters
Symbol Parameter Min Max Units
1/tCLCL Oscillator Frequency 0 20 MHz
tCLCL Clock Period 50 ns
tCHCX External Clock High Time 12 ns
tCLCX External Clock Low Time 12 ns
tCLCH External Clock Rise Time 5ns
tCHCL External Clock Fall Time 5ns
Table 25-3. Clock Characteristics
Symbol Parameter Condition Min Max Units
fXTAL Crystal Oscillator Frequency 0 20 MHz
fIRC Internal Oscillator Frequency TA = 25°C; VCC = 5.0V 7.92 8.08 MHz
VCC = 2.4V to 5.5V 7.70 8.50 MHz
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25.5 Serial Peripheral Interface Timing
Table 25-4. SPI Master Characteristics
Symbol Parameter Min Max Units
tCLCL Oscillator Period 41.6 ns
tSCK Serial Clock Cycle Time 4tCLCL ns
tSHSL Clock High Time tSCK/2 - 25 ns
tSLSH Clock Low Time tSCK/2 - 25 ns
tSR Rise Time 25 ns
tSF Fall Time 25 ns
tSIS Serial Input Setup Time 10 ns
tSIH Serial Input Hold Time 10 ns
tSOH Serial Output Hold Time 10 ns
tSOV Serial Output Valid Time 35 ns
Table 25-5. SPI Slave Characteristics
Symbol Parameter Min Max Units
tCLCL Oscillator Period 41.6 ns
tSCK Serial Clock Cycle Time 4tCLCL ns
tSHSL Clock High Time 1.5 tCLCL - 25 ns
tSLSH Clock Low Time 1.5 tCLCL - 25 ns
tSR Rise Time 25 ns
tSF Fall Time 25 ns
tSIS Serial Input Setup Time 10 ns
tSIH Serial Input Hold Time 10 ns
tSOH Serial Output Hold Time 10 ns
tSOV Serial Output Valid Time 35 ns
tSOE Output Enable Time 10 ns
tSOX Output Disable Time 25 ns
tSSE Slave Enable Lead Time 10 ns
tSSD Slave Disable Lag Time 0 ns
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Figure 25-13. SPI Master Timing (CPHA = 0)
Figure 25-14. SPI Slave Timing (CPHA = 0)
SS
SCK
(CPOL = 0)
SCK
(CPOL = 1)
MISO
MOSI
tSR
tSCK
tSLSH
tSLSH
tSHSL
tSHSL
tSOH
tSF
tSIS tSIH
tSOV
t
SR
t
SSE
t
SLSH
t
SHSL
t
SOV
t
SF
t
SOX
t
SSD
t
SCK
t
SLSH
t
SHSL
t
SOE
t
SOH
t
SIH
t
SIS
SS
SCK
(CPOL = 0)
SCK
(CPOL= 1)
MISO
MOSI
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Figure 25-15. SPI Master Timing (CPHA = 1)
Figure 25-16. SPI Slave Timing (CPHA = 1)
t
SHSL
t
SLSH
t
SHSL
t
SLSH
t
SCK
t
SOH
t
SF
t
SR
t
SIS
t
SOV
t
SIH
SS
SCK
(CPOL = 0)
SCK
(CPOL = 1)
MISO
MOSI
SS
SCK
(CPOL = 0)
SCK
(CPOL = 1)
MISO
MOSI
tSCK
tSSE
tSHSL
tSHSL
tSLSH
tSLSH
tSSD
tSIH
tSIS
tSOE tSOV tSOH tSOX
tSF tSR
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Figure 25-17. Shift Register Mode Timing Waveform
25.7 Test Conditions
25.7.1 AC Testing Input/Output Waveform(1)
Note: 1. AC Inputs during testing are driven at VCC - 0.5V for a logic “1” and 0.45V for a logic “0”. Timing measurements are made at
VIH min. for a logic “1” and VIL max. for a logic “0”.
25.7.2 Float Waveform(1)
Note: 1. For timing purposes, a port pin is no longer floating when a 100 mV change from load voltage occurs. A port pin begins to
float when 100 mV change from the loaded VOH/VOL level occurs.
25.6 Serial Port Timing: Shift Register Mode Test Conditions
The values in this table are valid for VCC = 2.4V to 5.5V and Load Capacitance = 80 pF.
Symbol Parameter
Variable Oscillator
UnitsMin Max
tXLXL Serial Port Clock Cycle Time 2tCLCL -15 µs
tQVXH Output Data Setup to Clock Rising Edge tCLCL -15 ns
tXHQX Output Data Hold after Clock Rising Edge tCLCL -15 ns
tXHDX Input Data Hold after Clock Rising Edge 0 ns
tXHDV Input Data Valid to Clock Rising Edge 15 ns
01234567
ValidValidValidValid Valid Valid Valid Valid
Clock
Write to SBUF
Output Data
Clear RI
Input Data
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25.7.3 ICC Test Condition, Active Mode, All Other Pins are Disconnected
25.7.4 ICC Test Condition, Idle Mode, All Other Pins are Disconnected
25.7.5 Clock Signal Waveform for ICC Tests in Active and Idle Modes, tCLCH = tCHCL = 5 ns
25.7.6 ICC Test Condition, Power-down Mode, All Other Pins are Disconnected, VCC = 2V to 5.5V
XTAL2
RSTV
CC
V
CC
I
CC
XTAL1
V
SS
(NC)
CLOCK SIGNAL
XTAL2
RSTV
CC
V
CC
I
CC
XTAL1
V
SS
(NC)
CLOCK SIGNAL
V
CC
- 0.5V
0.45V 0.2 V
CC
- 0.1V
0.7 V
CC
t
CHCX
t
CHCX
t
CLCH
t
CHCL
t
CLCL
XTAL2
RSTV
CC
V
CC
I
CC
XTAL1
VSS
(NC)
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26. Ordering Information
26.1 Green Package Option (Pb/Halide-free)
Speed
(MHz)
Power
Supply Ordering Code Package Operation Range
20 2.4V to 5.5V
AT89LP216-20PU
AT89LP216-20SU
AT89LP216-20XU
16P3
16S
16X
Industrial
(-40⋅C to 85⋅C)
Package Type
16P3 16-lead, 0.300” Wide, Plastic Dual In-line Package (PDIP)
16S 16-lead, 0.300” Wide, Plastic Gull Wing Small Outline (SOIC)
16X 16-lead, 0.173” Wide, Plastic Thin Shrink Small Outline Package (TSSOP)
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27. Packaging Information
27.1 16P3 – PDIP
2325 Orchard Parkway
San Jose, CA 95131
TITLE DRAWING NO.
R
REV.
16P3, 16-lead (0.300"/7.62 mm Wide) Plastic Dual
Inline Package (PDIP) A
16P3
11/02/05
PIN
1
E1
A1
B2
B
E
C
L
SEATING PLANE
A
D
e
eB eC
COMMON DIMENSIONS
(Unit of Measure = mm)
SYMBOL MIN NOM MAX NOTE
A – – 5.334
A1 0.381 – –
D 19.81 – 20.32 Note 2
E 7.620 – 8.255
E1 6.096 – 7.112 Note 2
B 0.356 – 0.559
B1 1.143 – 1.778
B2 0.762 – 1.143
L 2.921 – 3.810
C 0.203 – 0.356
eB – – 10.922
eC 0.000 – 1.524
e 2.540 TYP
Notes: 1. This package conforms to JEDEC reference MS-001, Variation AB.
2. Dimensions D and E1 do not include mold Flash or Protrusion.
Mold Flash or Protrusion shall not exceed 0.25 mm (0.010").
B1
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27.2 16S – SOIC
2325 Orchard Parkway
San Jose, CA 95131
TITLE DRAWING NO.
R
REV.
16S, 16-lead, 0.300" Wide Body, Plastic Gull
Wing Small Outline Package (SOIC)
11/02/05
16SA
A1
E
L
Side View
Top View
End View
H
E
b
N
1
e
A
D
C
COMMON DIMENSIONS
(Unit of Measure = mm)
SYMBOL MIN NOM MAX NOTE
Notes: 1. This drawing is for general information only; refer to JEDEC Drawing MS-013, Variation AA for additional information.
2. Dimension D does not include mold Flash, protrusions or gate burrs. Mold Flash, protrusion and gate burrs shall not
exceed 0.15 mm (0.006") per side.
3. Dimension E does not include inter-lead Flash or protrusion. Inter-lead flash and protrusions shall not exceed 0.25 mm
(0.010") per side.
4. L is the length of the terminal for soldering to a substrate.
A 2.35 – 2.65
A1 0.10 – 0.30
b 0.31 – 0.51
D 10.30 BSC 2
E 7.50 BSC 3
H 10.30 BSC
L 0.40 – 1.27 4
e 1.27 BSC
C 0.20 0.33
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27.3 16X – TSSOP
TITLE DRAWING NO.
R
REV.
2325 Orchard Parkway
San Jose, CA 95131
11/11/05
16X, 16-lead, 4.4 mm Body Width, Plastic Thin Shrink
Small Outline Package (TSSOP) 16X A
COMMON DIMENSIONS
(Unit of Measure = mm)
SYMBOL MIN NOM MAX NOTE
Note: These drawings are for general information only. Refer to JEDEC Drawing MO-153-AB.
A – – 1.20
A1 0.05 – 0.15
b 0.19 – 0.30
C 0.09 – 0.20
D 4.90 5.00 5.10
E1 4.30 4.40 4.50
E 6.40 BSC
e 0.65 TYP
L 0.45 0.60 0.75
Ø
0
o – 8o
CC
AA
bb
LL
A1A1
D
Side View
Top View
End View
EE
11
E1E1
e
ØØ
93
3621E–MICRO–11/10
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28. Revision History
Revision No. History
Revision A – July 2006 •Initial Preliminary Release
Revision B – Nov. 2007 •Removed “Preliminary” status from the datasheet.
Revision C – June 2008
•Added oscillator connection diagram, Figure 9-1 on page 11
•Added external clock connection diagram, Figure 9-2 on page 12
•Added PWM Mode 2 waveform, Figure 14-9 on page 34
•Updated SPI connection diagram, Figure 19-1 on page 50
•Add note for Tristate Ports Fuse on page 71
•Updated definition for OCD Interface Fuse on page 71
•Updated DC Parameters on page 76
•Added typical power consumption characteristics on page 77
•Added typical frequency characteristics on page 79
•Added typical I/O characteristics on page 80
•Updated Clock Parameters on page 83
•Removed Standard Packaging Offering
Revision D – Oct. 2009 •Replaced C1 with R1 in oscillator diagram Figure 9-1 on page 11.
•Added oscillator input characteristics on page 82.
Revision E – Nov. 2010 •Noted output levels as TTL. See Section 13. on page 22.
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i
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AT89LP216
Table of Contents
Features ..................................................................................................... 1
1 Description ............................................................................................... 1
2 Pin Configuration ..................................................................................... 2
2.1 16-lead PDIP/SOIC/TSSOP ..............................................................................2
3 Pin Description ......................................................................................... 3
4 Block Diagram .......................................................................................... 4
5 Comparison to Standard 8051 ................................................................ 4
5.1 System Clock .....................................................................................................4
5.2 Instruction Execution with Single-cycle Fetch ...................................................4
5.3 Interrupt Handling ..............................................................................................5
5.4 Timer/Counters ..................................................................................................5
5.5 Serial Port ..........................................................................................................5
5.6 Watchdog Timer ................................................................................................5
5.7 I/O Ports ............................................................................................................5
5.8 Reset .................................................................................................................5
6 Memory Organization .............................................................................. 6
6.1 Program Memory ...............................................................................................6
6.2 Data Memory .....................................................................................................7
7 Special Function Registers ..................................................................... 8
8 Enhanced CPU ......................................................................................... 9
8.1 Restrictions on Certain Instructions .................................................................10
9 System Clock ......................................................................................... 11
9.1 Crystal Oscillator .............................................................................................11
9.2 External Clock Source .....................................................................................12
9.3 Internal RC Oscillator ......................................................................................12
9.4 System Clock Out ............................................................................................12
10 Reset ....................................................................................................... 13
10.1 Power-on Reset ...............................................................................................13
10.2 Brown-out Reset ..............................................................................................15
10.3 External Reset .................................................................................................15
10.4 Watchdog Reset ..............................................................................................16
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Table of Contents (Continued)
10.5 Software Reset ................................................................................................16
11 Power Saving Modes ............................................................................. 16
11.1 Idle Mode .........................................................................................................16
11.2 Power-down Mode ...........................................................................................16
12 Interrupts ................................................................................................ 18
12.1 Interrupt Response Time .................................................................................20
13 I/O Ports .................................................................................................. 22
13.1 Port Configuration ............................................................................................22
13.2 Port 1 Analog Functions ..................................................................................25
13.3 Port Read-modify-write ....................................................................................25
13.4 Ports During Powerdown .................................................................................26
13.5 Port Alternate Functions ..................................................................................26
14 Enhanced Timer/Counters .................................................................... 27
14.1 Mode 0 – Variable Width Timer/Counter .........................................................27
14.2 Mode 1 – 16-bit Auto-Reload Timer/Counter ...................................................28
14.3 Mode 2 – 8-bit Auto-reload Timer/Counter ......................................................29
14.4 Mode 3 – 8-bit Split Timer ...............................................................................29
14.5 Pulse Width Modulation ...................................................................................32
15 External Interrupts ................................................................................. 36
16 General-purpose Interrupts .................................................................. 36
17 Serial Interface ....................................................................................... 38
17.1 Multiprocessor Communications .....................................................................38
18 Baud Rates ............................................................................................. 40
18.1 More About Mode 0 .........................................................................................41
18.2 More About Mode 1 .........................................................................................43
18.3 More About Modes 2 and 3 .............................................................................45
18.4 Framing Error Detection ..................................................................................48
18.5 Automatic Address Recognition ......................................................................48
19 Serial Peripheral Interface ..................................................................... 49
20 Analog Comparator ............................................................................... 55
20.1 Comparator Interrupt with Debouncing ............................................................55
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Table of Contents (Continued)
21 Programmable Watchdog Timer ........................................................... 57
21.1 Software Reset ................................................................................................58
22 Instruction Set Summary ...................................................................... 59
23 On-chip Debug System ......................................................................... 63
23.1 Physical Interface ............................................................................................63
23.2 Software Breakpoints ......................................................................................64
23.3 Limitations of On-chip Debug ..........................................................................64
24 Programming the Flash Memory .......................................................... 64
24.1 Physical Interface ............................................................................................65
24.2 Memory Organization ......................................................................................66
24.3 Command Format ............................................................................................67
24.4 Status Register ................................................................................................70
24.5 DATA Polling ...................................................................................................70
24.6 Flash Security ..................................................................................................70
24.7 User Configuration Fuses ................................................................................71
24.8 Programming Interface Timing ........................................................................72
25 Electrical Characteristics ...................................................................... 76
25.1 Absolute Maximum Ratings* ...........................................................................76
25.2 DC Characteristics ...........................................................................................76
25.3 Typical Characteristics ....................................................................................77
25.4 Clock Characteristics .......................................................................................83
25.5 Serial Peripheral Interface Timing ..................................................................84
25.6 Serial Port Timing: Shift Register Mode Test Conditions ................................87
25.7 Test Conditions ................................................................................................87
26 Ordering Information ............................................................................. 89
26.1 Green Package Option (Pb/Halide-free) ..........................................................89
27 Packaging Information .......................................................................... 90
27.1 16P3 – PDIP ....................................................................................................90
27.2 16S – SOIC .....................................................................................................91
27.3 16X – TSSOP ..................................................................................................92
28 Revision History ..................................................................................... 93
3621E–MICRO–11/10
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