ATMEL AT89

Features
• Compatible with MCS®51 Products
• 8K Bytes of In-System Reprogrammable Downloadable Flash Memory
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– SPI Serial Interface for Program Downloading
– Endurance: 1,000 Write/Erase Cycles
2K Bytes EEPROM
– Endurance: 100,000 Write/Erase Cycles
4V to 6V Operating Range
Fully Static Operation: 0 Hz to 24 MHz
Three-level Program Memory Lock
256 x 8-bit Internal RAM
32 Programmable I/O Lines
Three 16-bit Timer/Counters
Nine Interrupt Sources
Programmable UART Serial Channel
SPI Serial Interface
Low-power Idle and Power-down Modes
Interrupt Recovery from Power-down
Programmable Watchdog Timer
Dual Data Pointer
Power-off Flag
8-bit
Microcontroller
with 8K Bytes
Flash
AT89S8252
Description
The AT89S8252 is a low-power, high-performance CMOS 8-bit microcontroller with 8K
bytes of downloadable Flash programmable and erasable read-only memory and 2K
bytes of EEPROM. The device is manufactured using Atmel’s high-density nonvolatile
memory technology and is compatible with the industry-standard 80C51 instruction
set and pinout. The on-chip downloadable Flash allows the program memory to be
reprogrammed In-System through an SPI serial interface or by a conventional nonvolatile memory programmer. By combining a versatile 8-bit CPU with downloadable
Flash on a monolithic chip, the Atmel AT89S8252 is a powerful microcontroller, which
provides a highly-flexible and cost-effective solution to many embedded control
applications.
The AT89S8252 provides the following standard features: 8K bytes of downloadable
Flash, 2K bytes of EEPROM, 256 bytes of RAM, 32 I/O lines, programmable watchdog
timer, two data pointers, three 16-bit timer/counters, a six-vector two-level interrupt
architecture, a full duplex serial port, on-chip oscillator, and clock circuitry. In addition,
the AT89S8252 is designed with static logic for operation down to zero frequency and
supports two software selectable power saving modes. The Idle Mode stops the CPU
while allowing the RAM, timer/counters, serial port, and interrupt system to continue
functioning. The Power-down mode saves the RAM contents but freezes the oscillator,
disabling all other chip functions until the next external interrupt or hardware reset.
The downloadable Flash can be changed a single byte at a time and is accessible
through the SPI serial interface. Holding RESET active forces the SPI bus into a serial
programming interface and allows the program memory to be written to or read from
unless lock bits have been activated.
0401F–MICRO–11/03
1
Pin Configurations
TQFP
VCC
P0.0 (AD0)
P0.1 (AD1)
P0.2 (AD2)
P0.3 (AD3)
P0.4 (AD4)
P0.5 (AD5)
P0.6 (AD6)
P0.7 (AD7)
EA/VPP
ALE/PROG
PSEN
P2.7 (A15)
P2.6 (A14)
P2.5 (A13)
P2.4 (A12)
P2.3 (A11)
P2.2 (A10)
P2.1 (A9)
P2.0 (A8)
44
43
42
41
40
39
38
37
36
35
34
40
39
38
37
36
35
34
33
32
31
30
29
28
27
26
25
24
23
22
21
(MOSI) P1.5
(MISO) P1.6
(SCK) P1.7
RST
(RXD) P3.0
NC
(TXD) P3.1
(INT0) P3.2
(INT1) P3.3
(T0) P3.4
(T1) P3.5
33
32
31
30
29
28
27
26
25
24
23
1
2
3
4
5
6
7
8
9
10
11
P0.4 (AD4)
P0.5 (AD5)
P0.6 (AD6)
P0.7 (AD7)
EA/VPP
NC
ALE/PROG
PSEN
P2.7 (A15)
P2.6 (A14)
P2.5 (A13)
12
13
14
15
16
17
18
19
20
21
22
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
(WR) P3.6
(RD) P3.7
XTAL2
XTAL1
GND
GND
(A8) P2.0
(A9) P2.1
(A10) P2.2
(A11) P2.3
(A12) P2.4
(T2) P1.0
(T2 EX) P1.1
P1.2
P1.3
(SS) P1.4
(MOSI) P1.5
(MISO) P1.6
(SCK) P1.7
RST
(RXD) P3.0
(TXD) P3.1
(INT0) P3.2
(INT1) P3.3
(T0) P3.4
(T1) P3.5
(WR) P3.6
(RD) P3.7
XTAL2
XTAL1
GND
P1.4 (SS)
P1.3
P1.2
P1.1 (T2 EX)
P1.0 (T2)
NC
VCC
P0.0 (AD0)
P0.1 (AD1)
P0.2 (AD2)
P0.3 (AD3)
PDIP
39
38
37
36
35
34
33
32
31
30
29
18
19
20
21
22
23
24
25
26
27
28
7
8
9
10
11
12
13
14
15
16
17
P0.4 (AD4)
P0.5 (AD5)
P0.6 (AD6)
P0.7 (AD7)
EA/VPP
NC
ALE/PROG
PSEN
P2.7 (A15)
P2.6 (A14)
P2.5 (A13)
(WR) P3.6
(RD) P3.7
XTAL2
XTAL1
GND
NC
(A8) P2.0
(A9) P2.1
(A10) P2.2
(A11) P2.3
(A12) P2.4
(MOSI) P1.5
(MISO) P1.6
(SCK) P1.7
RST
(RXD) P3.0
NC
(TXD) P3.1
(INT0) P3.2
(INT1) P3.3
(T0) P3.4
(T1) P3.5
6
5
4
3
2
1
44
43
42
41
40
P1.4 (SS)
P1.3
P1.2
P1.1 (T2 EX)
P1.0 (T2)
NC
VCC
P0.0 (AD0)
P0.1 (AD1)
P0.2 (AD2)
P0.3 (AD3)
PLCC
Pin Description
VCC
Supply voltage.
GND
Ground.
Port 0
Port 0 is an 8-bit open drain bi-didirectional I/O port. As an output port, each pin can
sink eight TTL inputs. When 1s are written to port 0 pins, the pins can be used as highimpedance inputs.
Port 0 can also be configured to be the multiplexed low-order address/data bus during
accesses to external program and data memory. In this mode, P0 has internal pull-ups.
Port 0 also receives the code bytes during Flash programming and outputs the code
bytes during program verification. External pull-ups are required during program
verification.
Port 1
2
Port 1 is an 8-bit bi-directional I/O port with internal pull-ups. The Port 1 output buffers
can sink/source four TTL inputs. When 1s are written to Port 1 pins, they are pulled high
by the internal pull-ups and can be used as inputs. As inputs, Port 1 pins that are externally being pulled low will source current (IIL) because of the internal pull-ups.
AT89S8252
0401F–MICRO–11/03
AT89S8252
Block Diagram
P0.0 - P0.7
P2.0 - P2.7
PORT 0 DRIVERS
PORT 2 DRIVERS
VCC
GND
EEPROM
RAM ADDR.
REGISTER
B
REGISTER
PORT 0
LATCH
RAM
PORT 2
LATCH
FLASH
PROGRAM
ADDRESS
REGISTER
STACK
POINTER
ACC
BUFFER
TMP2
TMP1
PC
INCREMENTER
ALU
INTERRUPT, SERIAL PORT,
AND TIMER BLOCKS
PROGRAM
COUNTER
PSW
PSEN
ALE/PROG
EA / VPP
TIMING
AND
CONTROL
DUAL
DPTR
INSTRUCTION
REGISTER
RST
WATCH
DOG
PORT 3
LATCH
PORT 1
LATCH
SPI
PORT
PROGRAM
LOGIC
OSC
PORT 3 DRIVERS
P3.0 - P3.7
PORT 1 DRIVERS
P1.0 - P1.7
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0401F–MICRO–11/03
Some Port 1 pins provide additional functions. P1.0 and P1.1 can be configured to be
the timer/counter 2 external count input (P1.0/T2) and the timer/counter 2 trigger input
(P1.1/T2EX), respectively.
Furthermore, P1.4, P1.5, P1.6, and P1.7 can be configured as the SPI slave port select,
data input/output and shift clock input/output pins as shown in the following table.
Port Pin
Alternate Functions
P1.0
T2 (external count input to Timer/Counter 2), clock-out
P1.1
T2EX (Timer/Counter 2 capture/reload trigger and direction control)
P1.4
SS (Slave port select input)
P1.5
MOSI (Master data output, slave data input pin for SPI channel)
P1.6
MISO (Master data input, slave data output pin for SPI channel)
P1.7
SCK (Master clock output, slave clock input pin for SPI channel)
Port 1 also receives the low-order address bytes during Flash programming and
verification.
Port 2
Port 2 is an 8-bit bi-directional I/O port with internal pull-ups. The Port 2 output buffers
can sink/source four TTL inputs. When 1s are written to Port 2 pins, they are pulled high
by the internal pull-ups and can be used as inputs. As inputs, Port 2 pins that are externally being pulled low will source current (IIL) because of the internal pull-ups.
Port 2 emits the high-order address byte during fetches from external program memory
and during accesses to external data memory that use 16-bit addresses (MOVX @
DPTR). In this application, Port 2 uses strong internal pull-ups when emitting 1s. During
accesses to external data memory that use 8-bit addresses (MOVX @ RI), Port 2 emits
the contents of the P2 Special Function Register.
Port 2 also receives the high-order address bits and some control signals during Flash
programming and verification.
Port 3
Port 3 is an 8-bit bi-directional I/O port with internal pull-ups. The Port 3 output buffers
can sink/source four TTL inputs. When 1s are written to Port 3 pins, they are pulled high
by the internal pull-ups and can be used as inputs. As inputs, Port 3 pins that are externally being pulled low will source current (IIL) because of the pull-ups.
Port 3 receives some control signals for Flash programming and verification.
Port 3 also serves the functions of various special features of the AT89S8252, as shown
in the following table.
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AT89S8252
0401F–MICRO–11/03
AT89S8252
Port Pin
Alternate Functions
P3.0
RXD (serial input port)
P3.1
TXD (serial output port)
P3.2
INT0 (external interrupt 0)
P3.3
INT1 (external interrupt 1)
P3.4
T0 (timer 0 external input)
P3.5
T1 (timer 1 external input)
P3.6
WR (external data memory write strobe)
P3.7
RD (external data memory read strobe)
RST
Reset input. A high on this pin for two machine cycles while the oscillator is running
resets the device.
ALE/PROG
Address Latch Enable is an output pulse for latching the low byte of the address during
accesses to external memory. This pin is also the program pulse input (PROG) during
Flash programming.
In normal operation, ALE is emitted at a constant rate of 1/6 the oscillator frequency and
may be used for external timing or clocking purposes. Note, however, that one ALE
pulse is skipped during each access to external data memory.
If desired, ALE operation can be disabled by setting bit 0 of SFR location 8EH. With the
bit set, ALE is active only during a MOVX or MOVC instruction. Otherwise, the pin is
weakly pulled high. Setting the ALE-disable bit has no effect if the microcontroller is in
external execution mode.
PSEN
Program Store Enable is the read strobe to external program memory.
When the AT89S8252 is executing code from external program memory, PSEN is activated twice each machine cycle, except that two PSEN activations are skipped during
each access to external data memory.
EA/VPP
External Access Enable. EA must be strapped to GND in order to enable the device to
fetch code from external program memory locations starting at 0000H up to FFFFH.
Note, however, that if lock bit 1 is programmed, EA will be internally latched on reset.
EA should be strapped to VCC for internal program executions. This pin also receives the
12-volt programming enable voltage (VPP) during Flash programming when 12-volt programming is selected.
XTAL1
Input to the inverting oscillator amplifier and input to the internal clock operating circuit.
XTAL2
Output from the inverting oscillator amplifier.
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0401F–MICRO–11/03
Special Function
Registers
A map of the on-chip memory area called the Special Function Register (SFR) space is
shown in Table 1.
Note that not all of the addresses are occupied, and unoccupied addresses may not be
implemented 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 1s to these unlisted locations, since they may be used in
future products to invoke new features. In that case, the reset or inactive values of the
new bits will always be 0.
Timer 2 Registers Control and status bits are contained in registers T2CON (shown in
Table 2) and T2MOD (shown in Table 9) for Timer 2. The register pair (RCAP2H,
RCAP2L) are the Capture/Reload registers for Timer 2 in 16-bit capture mode or 16-bit
auto-reload mode.
Table 1. AT89S8252 SFR Map and Reset Values
0F8H
0F0H
0FFH
B
00000000
0F7H
0E8H
0E0H
0EFH
ACC
00000000
0E7H
0DF
H
0D8H
0D0H
PSW
00000000
0C8H
T2CON
00000000
T2MOD
XXXXXX00
RCAP2L
00000000
RCAP2H
00000000
TL2
00000000
SPCR
000001XX
0D7H
TH2
00000000
0CF
H
0C0H
6
0C7H
0B8H
IP
XX000000
0BFH
0B0H
P3
11111111
0B7H
0A8H
IE
0X000000
0A0H
P2
11111111
98H
SCON
00000000
90H
P1
11111111
88H
TCON
00000000
TMOD
00000000
TL0
00000000
TL1
00000000
TH0
00000000
TH1
00000000
80H
P0
11111111
SP
00000111
DP0L
00000000
DP0H
00000000
DP1L
00000000
DP1H
00000000
SPSR
00XXXXXX
0AFH
0A7H
SBUF
XXXXXXXX
9FH
WMCON
00000010
97H
8FH
SPDR
XXXXXXXX
PCON
0XXX0000
87H
AT89S8252
0401F–MICRO–11/03
AT89S8252
Table 2. T2CON – Timer/Counter 2 Control Register
T2CON Address = 0C8H
Reset Value = 0000 0000B
Bit Addressable
Bit
TF2
EXF2
RCLK
TCLK
EXEN2
TR2
C/T2
CP/RL2
7
6
5
4
3
2
1
0
Symbol
Function
TF2
Timer 2 overflow flag set by a Timer 2 overflow and must be cleared by software. TF2 will not be set when either
RCLK = 1 or TCLK = 1.
EXF2
Timer 2 external flag set when either a capture or reload is caused by a negative transition on T2EX and EXEN2 = 1.
When Timer 2 interrupt is enabled, EXF2 = 1 will cause the CPU to vector to the Timer 2 interrupt routine. EXF2 must be
cleared by software. EXF2 does not cause an interrupt in up/down counter mode (DCEN = 1).
RCLK
Receive clock enable. When set, causes the serial port to use Timer 2 overflow pulses for its receive clock in serial port
Modes 1 and 3. RCLK = 0 causes Timer 1 overflows to be used for the receive clock.
TCLK
Transmit clock enable. When set, causes the serial port to use Timer 2 overflow pulses for its transmit clock in serial port
Modes 1 and 3. TCLK = 0 causes Timer 1 overflows to be used for the transmit clock.
EXEN2
Timer 2 external enable. When set, allows a capture or reload to occur as a result of a negative transition on T2EX if
Timer 2 is not being used to clock the serial port. EXEN2 = 0 causes Timer 2 to ignore events at T2EX.
TR2
Start/Stop control for Timer 2. TR2 = 1 starts the timer.
C/T2
Timer or counter select for Timer 2. C/T2 = 0 for timer function. C/T2 = 1 for external event counter (falling edge
triggered).
CP/RL2
Capture/Reload select. CP/RL2 = 1 causes captures to occur on negative transitions at T2EX if EXEN2 = 1. CP/RL2 = 0
causes automatic reloads to occur when Timer 2 overflows or negative transitions occur at T2EX when EXEN2 = 1. When
either RCLK or TCLK = 1, this bit is ignored and the timer is forced to auto-reload on Timer 2 overflow.
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0401F–MICRO–11/03
Watchdog and Memory Control Register The WMCON register contains control bits for the Watchdog Timer (shown in
Table 3). The EEMEN and EEMWE bits are used to select the 2K bytes on-chip EEPROM, and to enable byte-write. The
DPS bit selects one of two DPTR registers available.
Table 3. WMCON—Watchdog and Memory Control Register
WMCON Address = 96H
Bit
Reset Value = 0000 0010B
PS2
PS1
PS0
EEMWE
EEMEN
DPS
WDTRST
WDTEN
7
6
5
4
3
2
1
0
Symbol
Function
PS2
PS1
PS0
Prescaler Bits for the Watchdog Timer. When all three bits are set to “0”, the watchdog timer has a nominal period of
16 ms. When all three bits are set to “1”, the nominal period is 2048 ms.
EEMWE
EEPROM Data Memory Write Enable Bit. Set this bit to “1” before initiating byte write to on-chip EEPROM with the
MOVX instruction. User software should set this bit to “0” after EEPROM write is completed.
EEMEN
Internal EEPROM Access Enable. When EEMEN = 1, the MOVX instruction with DPTR will access on-chip EEPROM
instead of external data memory. When EEMEN = 0, MOVX with DPTR accesses external data memory.
DPS
Data Pointer Register Select. DPS = 0 selects the first bank of Data Pointer Register, DP0, and DPS = 1 selects the
second bank, DP1
WDTRST
RDY/BSY
Watchdog Timer Reset and EEPROM Ready/Busy Flag. Each time this bit is set to “1” by user software, a pulse is
generated to reset the watchdog timer. The WDTRST bit is then automatically reset to “0” in the next instruction cycle.
The WDTRST bit is Write-Only. This bit also serves as the RDY/BSY flag in a Read-Only mode during EEPROM write.
RDY/BSY = 1 means that the EEPROM is ready to be programmed. While programming operations are being executed,
the RDY/BSY bit equals “0” and is automatically reset to “1” when programming is completed.
WDTEN
Watchdog Timer Enable Bit. WDTEN = 1 enables the watchdog timer and WDTEN = 0 disables the watchdog timer.
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AT89S8252
0401F–MICRO–11/03
AT89S8252
SPI Registers Control and status bits for the Serial Peripheral Interface are contained in
registers SPCR (shown in Table 4) and SPSR (shown in Table 5). The SPI data bits are
contained in the SPDR register. Writing the SPI data register during serial data transfer
sets the Write Collision bit, WCOL, in the SPSR register. The SPDR is double buffered
for writing and the values in SPDR are not changed by Reset.
Interrupt Registers The global interrupt enable bit and the individual interrupt enable
bits are in the IE register. In addition, the individual interrupt enable bit for the SPI is in
the SPCR register. Two priorities can be set for each of the six interrupt sources in the
IP register.
Dual Data Pointer Registers To facilitate accessing both internal EEPROM and external data memory, two banks of 16-bit Data Pointer Registers are provided: DP0 at SFR
address locations 82H-83H and DP1 at 84H-85H. Bit DPS = 0 in SFR WMCON selects
DP0 and DPS = 1 selects DP1. The user should ALWAYS initialize the DPS bit to the
appropriate value before accessing the respective Data Pointer Register.
Power Off Flag The Power Off Flag (POF) is located at bit_4 (PCON.4) in the PCON
SFR. POF is set to “1” during power up. It can be set and reset under software control
and is not affected by RESET.
Table 4. SPCR – SPI Control Register
SPCR Address = D5H
Bit
Reset Value = 0000 01XXB
SPIE
SPE
DORD
MSTR
CPOL
CPHA
SPR1
SPR0
7
6
5
4
3
2
1
0
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 = FOSC. divided by
0
0
4
0
1
16
1
0
64
1
1
128
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0401F–MICRO–11/03
Table 5. SPSR – SPI Status Register
SPSR Address = AAH
Bit
Reset Value = 00XX XXXXB
SPIF
WCOL
–
–
–
–
–
–
7
6
5
4
3
2
1
0
Symbol
Function
SPIF
SPI 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 with SPIF and WCOL bits set, and then reading/writing the
SPI data register.
WCOL
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 with SPIF and WCOL set, and then accessing the SPI data register.
Table 6. SPDR – SPI Data Register
SPDR Address = 86H
Bit
Reset Value = unchanged
SPD7
SPD6
SPD5
SPD4
SPD3
SPD2
SPD1
SPD0
7
6
5
4
3
2
1
0
Data Memory –
EEPROM and RAM
The AT89S8252 implements 2K bytes of on-chip EEPROM for data storage and 256
bytes of RAM. The upper 128 bytes of RAM occupy a parallel space to the Special
Function Registers. That means the upper 128 bytes have the same addresses as the
SFR space but are physically separate from SFR space.
When an instruction accesses an internal location above address 7FH, the address
mode used in the instruction specifies whether the CPU accesses the upper 128 bytes
of RAM or the SFR space. Instructions that use direct addressing access SFR space.
For example, the following direct addressing instruction accesses the SFR at location
0A0H (which is P2).
MOV 0A0H, #data
Instructions that use indirect addressing access the upper 128 bytes of RAM. For example, the following indirect addressing instruction, where R0 contains 0A0H, accesses the
data byte at address 0A0H, rather than P2 (whose address is 0A0H).
MOV @R0, #data
Note that stack operations are examples of indirect addressing, so the upper 128 bytes
of data RAM are available as stack space.
The on-chip EEPROM data memory is selected by setting the EEMEN bit in the
WMCON register at SFR address location 96H. The EEPROM address range is from
000H to 7FFH. The MOVX instructions are used to access the EEPROM. To access offchip data memory with the MOVX instructions, the EEMEN bit needs to be set to “0”.
The EEMWE bit in the WMCON register needs to be set to “1” before any byte location
in the EEPROM can be written. User software should reset EEMWE bit to “0” if no further EEPROM write is required. EEPROM write cycles in the serial programming mode
are self-timed and typically take 2.5 ms. The progress of EEPROM write can be monitored by reading the RDY/BSY bit (read-only) in SFR WMCON. RDY/BSY = 0 means
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AT89S8252
0401F–MICRO–11/03
AT89S8252
programming is still in progress and RDY/BSY = 1 means EEPROM write cycle is completed and another write cycle can be initiated.
In addition, during EEPROM programming, an attempted read from the EEPROM will
fetch the byte being written with the MSB complemented. Once the write cycle is completed, true data are valid at all bit locations.
Programmable
Watchdog Timer
The programmable Watchdog Timer (WDT) operates from an independent internal
oscillator. The prescaler bits, PS0, PS1 and PS2 in SFR WMCON are used to set the
period of the Watchdog Timer from 16 ms to 2048 ms. The available timer periods are
shown in the following table and the actual timer periods (at VCC = 5V) are within ±30%
of the nominal.
The WDT is disabled by Power-on Reset and during Power-down. It is enabled by setting the WDTEN bit in SFR WMCON (address = 96H). The WDT is reset by setting the
WDTRST bit in WMCON. When the WDT times out without being reset or disabled, an
internal RST pulse is generated to reset the CPU.
Table 7. Watchdog Timer Period Selection
WDT Prescaler Bits
PS2
PS1
PS0
Period (nominal)
0
0
0
16 ms
0
0
1
32 ms
0
1
0
64 ms
0
1
1
128 ms
1
0
0
256 ms
1
0
1
512 ms
1
1
0
1024 ms
1
1
1
2048 ms
Timer 0 and 1
Timer 0 and Timer 1 in the AT89S8252 operate the same way as Timer 0 and Timer 1 in
the AT89C51 and AT89C52. For further information on the timers’ operation, refer to the
Atmel web site (http://www.atmel.com). From the home page, select “Products”, then
“Microcontrollers, then “8051-Architecture”. Click on “Documentation”, then on “Other
Documents”. Open the document “AT89 Series Hardware Description”.
Timer 2
Timer 2 is a 16-bit Timer/Counter that can operate as either a timer or an event counter.
The type of operation is selected by bit C/T2 in the SFR T2CON (shown in Table 2).
Timer 2 has three operating modes: capture, auto-reload (up or down counting), and
baud rate generator. The modes are selected by bits in T2CON, as shown in Table 8.
Timer 2 consists of two 8-bit registers, TH2 and TL2. In the Timer function, the TL2 register is incremented every machine cycle. Since a machine cycle consists of 12
oscillator periods, the count rate is 1/12 of the oscillator frequency.
In the Counter function, the register is incremented in response to a 1-to-0 transition at
its corresponding external input pin, T2. In this function, the external input is sampled
during S5P2 of every machine 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 S3P1 of the cycle following the one in which the transition was detected.
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0401F–MICRO–11/03
Since two machine cycles (24 oscillator periods) are required to recognize a 1-to-0 transition, the maximum count rate is 1/24 of the oscillator frequency. To ensure that a given
level is sampled at least once before it changes, the level should be held for at least one
full machine cycle.
Table 8. Timer 2 Operating Modes
Capture Mode
RCLK + TCLK
CP/RL2
TR2
MODE
0
0
1
16-bit Auto-reload
0
1
1
16-bit Capture
1
X
1
Baud Rate Generator
X
X
0
(Off)
In the capture mode, two options are selected by bit EXEN2 in T2CON. If EXEN2 = 0,
Timer 2 is a 16-bit timer or counter which upon overflow sets bit TF2 in T2CON. This bit
can then be used to generate an interrupt. If EXEN2 = 1, Timer 2 performs the same
operation, but a l-to-0 transition at external input T2EX also causes the current value in
TH2 and TL2 to be captured into RCAP2H and RCAP2L, respectively. In addition, the
transition at T2EX causes bit EXF2 in T2CON to be set. The EXF2 bit, like TF2, can
generate an interrupt. The capture mode is illustrated in Figure 1.
Figure 1. Timer 2 in Capture Mode
÷12
OSC
C/T2 = 0
TH2
TL2
OVERFLOW
CONTROL
C/T2 = 1
TF2
TR2
CAPTURE
T2 PIN
RCAP2H RCAP2L
TRANSITION
DETECTOR
TIMER 2
INTERRUPT
T2EX PIN
EXF2
CONTROL
EXEN2
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AT89S8252
0401F–MICRO–11/03
AT89S8252
Auto-reload (Up or Down
Counter)
Timer 2 can be programmed to count up or down when configured in its 16-bit autoreload mode. This feature is invoked by the DCEN (Down Counter Enable) bit located in
the SFR T2MOD (see Table 9). Upon reset, the DCEN bit is set to 0 so that timer 2 will
default to count up. When DCEN is set, Timer 2 can count up or down, depending on the
value of the T2EX pin.
Figure 2 shows Timer 2 automatically counting up when DCEN = 0. In this mode, two
options are selected by bit EXEN2 in T2CON. If EXEN2 = 0, Timer 2 counts up to
0FFFFH and then sets the TF2 bit upon overflow. The overflow also causes the timer
registers to be reloaded with the 16-bit value in RCAP2H and RCAP2L. The values in
RCAP2H and RCAP2L are preset by software. If EXEN2 = 1, a 16-bit reload can be triggered either by an overflow or by a 1-to-0 transition at external input T2EX. This
transition also sets the EXF2 bit. Both the TF2 and EXF2 bits can generate an interrupt
if enabled.
Setting the DCEN bit enables Timer 2 to count up or down, as shown in Figure 3. In this
mode, the T2EX pin controls the direction of the count. A logic 1 at T2EX makes Timer 2
count up. The timer will overflow at 0FFFFH and set the TF2 bit. This overflow also
causes the 16-bit value in RCAP2H and RCAP2L to be reloaded into the timer registers,
TH2 and TL2, respectively.
A logic 0 at T2EX makes Timer 2 count down. The timer underflows when TH2 and TL2
equal the values stored in RCAP2H and RCAP2L. The underflow sets the TF2 bit and
causes 0FFFFH to be reloaded into the timer registers.
The EXF2 bit toggles whenever Timer 2 overflows or underflows and can be used as a
17th bit of resolution. In this operating mode, EXF2 does not flag an interrupt.
Figure 2. Timer 2 in Auto Reload Mode (DCEN = 0)
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0401F–MICRO–11/03
Table 9. T2MOD – Timer 2 Mode Control Register
T2MOD Address = 0C9H
Reset Value = XXXX XX00B
Not Bit Addressable
Bit
–
–
–
–
–
–
T2OE
DCEN
7
6
5
4
3
2
1
0
Symbol
Function
–
Not implemented, reserved for future use.
T2OE
Timer 2 Output Enable bit.
DCEN
When set, this bit allows Timer 2 to be configured as an up/down counter.
Figure 3. Timer 2 Auto Reload Mode (DCEN = 1)
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AT89S8252
0401F–MICRO–11/03
AT89S8252
Figure 4. Timer 2 in Baud Rate Generator Mode
TIMER 1 OVERFLOW
÷2
"0"
"1"
NOTE: OSC. FREQ. IS DIVIDED BY 2, NOT 12
SMOD1
OSC
÷2
C/T2 = 0
"1"
TH2
"0"
TL2
RCLK
CONTROL
TR2
÷16
Rx
CLOCK
C/T2 = 1
"1"
"0"
T2 PIN
TCLK
RCAP2H RCAP2L
TRANSITION
DETECTOR
÷ 16
T2EX PIN
EXF2
Tx
CLOCK
TIMER 2
INTERRUPT
CONTROL
EXEN2
Baud Rate Generator
Timer 2 is selected as the baud rate generator by setting TCLK and/or RCLK in T2CON
(Table 2). Note that the baud rates for transmit and receive can be different if Timer 2
is used for the receiver or transmitter and Timer 1 is used for the other function.
Setting RCLK and/or TCLK puts Timer 2 into its baud rate generator mode, as shown in
Figure 4.
The baud rate generator mode is similar to the auto-reload mode, in that a rollover in
TH2 causes the Timer 2 registers to be reloaded with the 16-bit value in registers
RCAP2H and RCAP2L, which are preset by software.
The baud rates in Modes 1 and 3 are determined by Timer 2’s overflow rate according to
the following equation.
2 Overflow RateModes 1 and 3 Baud Rates = Timer
----------------------------------------------------------16
The Timer can be configured for either timer or counter operation. In most applications,
it is configured for timer operation (CP/T2 = 0). The timer operation is different for Timer
2 when it is used as a baud rate generator. Normally, as a timer, it increments every
machine cycle (at 1/12 the oscillator frequency). As a baud rate generator, however, it
increments every state time (at 1/2 the oscillator frequency). The baud rate formula is
given below.
Modes 1 and 3
Oscillator Frequency
--------------------------------------- = ----------------------------------------------------------------------------------------------Baud Rate
32 × [ 65536 – ( RCAP2H,RCAP2L ) ]
where (RCAP2H, RCAP2L) is the content of RCAP2H and RCAP2L taken as a 16-bit
unsigned integer.
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0401F–MICRO–11/03
Timer 2 as a baud rate generator is shown in Figure 4. This figure is valid only if RCLK
or TCLK = 1 in T2CON. Note that a rollover in TH2 does not set TF2 and will not generate an interrupt. Note too, that if EXEN2 is set, a 1-to-0 transition in T2EX will set EXF2
but will not cause a reload from (RCAP2H, RCAP2L) to (TH2, TL2). Thus when Timer 2
is in use as a baud rate generator, T2EX can be used as an extra external interrupt.
Note that when Timer 2 is running (TR2 = 1) as a timer in the baud rate generator mode,
TH2 or TL2 should not be read from or written to. Under these conditions, the Timer is
incremented every state time, and the results of a read or write may not be accurate.
The RCAP2 registers may be read but should not be written to, because a write might
overlap a reload and cause write and/or reload errors. The timer should be turned off
(clear TR2) before accessing the Timer 2 or RCAP2 registers.
Programmable
Clock Out
A 50% duty cycle clock can be programmed to come out on P1.0, as shown in Figure 5.
This pin, besides being a regular I/0 pin, has two alternate functions. It can be programmed to input the external clock for Timer/Counter 2 or to output a 50% duty cycle
clock ranging from 61 Hz to 4 MHz (for a 16-MHz operating frequency).
To configure the Timer/Counter 2 as a clock generator, bit C/T2 (T2CON.1) must be
cleared and bit T2OE (T2MOD.1) must be set. Bit TR2 (T2CON.2) starts and stops the
timer.
The clock-out frequency depends on the oscillator frequency and the reload value of
Timer 2 capture registers (RCAP2H, RCAP2L), as shown in the following equation.
Oscillator Frequency
Clock Out Frequency = -------------------------------------------------------------------------------------------4 × [ 65536 – ( RCAP2H,RCAP2L ) ]
In the clock-out mode, Timer 2 rollovers will not generate an interrupt. This behavior is
similar to when Timer 2 is used as a baud-rate generator. It is possible to use Timer 2 as
a baud-rate generator and a clock generator simultaneously. Note, however, that the
baud-rate and clock-out frequencies cannot be determined independently from one
another since they both use RCAP2H and RCAP2L.
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AT89S8252
0401F–MICRO–11/03
AT89S8252
Figure 5. Timer 2 in Clock-out Mode
Figure 6. SPI Block Diagram
S
MSB
LSB
S
8/16-BIT SHIFT REGISTER
READ DATA BUFFER
DIVIDER
÷4÷16÷64÷128
CLOCK
SPI CLOCK (MASTER)
S
CLOCK
LOGIC
MOSI
P1.5
SCK
1.7
M
SPR0
SELECT
SPI STATUS REGISTER
DORD
SPR0
SPR1
CPHA
CPOL
MSTR
DORD
SPE
8
SPIE
MSTR
SPE
WCOL
SPI CONTROL
SPE
SS
P1.4
MSTR
SPR1
PIN CONTROL LOGIC
OSCILLATOR
SPIF
MISO
P1.6
M
M
SPI CONTROL REGISTER
8
8
SPI INTERRUPT INTERNAL
REQUEST
DATA BUS
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0401F–MICRO–11/03
UART
The UART in the AT89S8252 operates the same way as the UART in the AT89C51 and
AT89C52. For further information on the UART operation, refer to the Atmel web site
(http://www.atmel.com). From the home page, select “Products”, then “Microcontrollers,
then “8051-Architecture”. Click on “Documentation”, then on “Other Documents”. Open
the document “AT89 Series Hardware Description”.
Serial Peripheral
Interface
The serial peripheral interface (SPI) allows high-speed synchronous data transfer
between the AT89S8252 and peripheral devices or between several AT89S8252
devices. The AT89S8252 SPI features include the following:
•
Full-Duplex, 3-Wire Synchronous Data Transfer
•
Master or Slave Operation
•
1.5 MHz Bit Frequency (max.)
•
LSB First or MSB First Data Transfer
•
Four Programmable Bit Rates
•
End of Transmission Interrupt Flag
•
Write Collision Flag Protection
•
Wakeup from Idle Mode (Slave Mode Only)
The interconnection between master and slave CPUs with SPI is shown in the following
figure. The SCK pin is the clock output in the master mode but is the clock input in the
slave mode. Writing to the SPI data register 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. After shifting one byte, the SPI clock generator stops, setting the end of transmission flag (SPIF). If both the SPI interrupt enable bit (SPIE) and the serial port interrupt
enable bit (ES) are set, an interrupt is requested.
The Slave Select input, SS/P1.4, is set low to select an individual SPI device as a slave.
When SS/P1.4 is set high, the SPI port is deactivated and the MOSI/P1.5 pin can be
used as an input.
There are four combinations of SCK phase and polarity with respect to serial data,
which are determined by control bits CPHA and CPOL. The SPI data transfer formats
are shown in Figure 8 and Figure 9.
Figure 7. SPI Master-slave Interconnection
MSB
MASTER
LSB
MISO MISO
8-BIT SHIFT REGISTER
MSB
SLAVE
LSB
8-BIT SHIFT REGISTER
MOSI MOSI
SPI
CLOCK GENERATOR
SCK
SS
SCK
SS
VCC
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AT89S8252
0401F–MICRO–11/03
AT89S8252
Figure 8. SPI transfer Format with CPHA = 0
Note:
*Not defined but normally MSB of character just received
Figure 9. SPI Transfer Format with CPHA = 1
SCK CYCLE #
(FOR REFERENCE)
1
2
3
4
5
6
7
8
SCK (CPOL=0)
SCK (CPOL=1)
MOSI
(FROM MASTER)
MISO
(FROM SLAVE)
*
MSB
6
5
4
3
2
1
MSB
6
5
4
3
2
1
LSB
LSB
SS (TO SLAVE)
Note:
*Not defined but normally LSB of previously transmitted character.
Interrupts
The AT89S8252 has a total of six interrupt vectors: two external interrupts (INT0 and
INT1), three timer interrupts (Timers 0, 1, and 2), and the serial port interrupt. These
interrupts are all shown in Figure 10.
Each of these interrupt sources can be individually enabled or disabled by setting or
clearing a bit in Special Function Register IE. IE also contains a global disable bit, EA,
which disables all interrupts at once.
Note that Table 10 shows that bit position IE.6 is unimplemented. In the AT89C51, bit
position IE.5 is also unimplemented. User software should not write 1s to these bit positions, since they may be used in future AT89 products.
Timer 2 interrupt is generated by the logical OR of bits TF2 and EXF2 in register
T2CON. Neither of these flags is cleared by hardware when the service routine is vectored to. In fact, the service routine may have to determine whether it was TF2 or EXF2
that generated the interrupt, and that bit will have to be cleared in software.
The Timer 0 and Timer 1 flags, TF0 and TF1, are set at S5P2 of the cycle in which the
timers overflow. The values are then polled by the circuitry in the next cycle. However,
the Timer 2 flag, TF2, is set at S2P2 and is polled in the same cycle in which the timer
overflows.
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0401F–MICRO–11/03
Table 10. Interrupt Enable (IE) Register
(MSB)(LSB)
EA
–
ET2
ES
ET1
EX1
ET0
EX0
Enable Bit = 1 enables the interrupt.
Enable Bit = 0 disables the interrupt.
Symbol
Position
Function
EA
IE.7
Disables all interrupts. If EA = 0, no interrupt is acknowledged. If EA = 1, each interrupt
source is individually enabled or disabled by setting or clearing its enable bit.
–
IE.6
Reserved.
ET2
IE.5
Timer 2 interrupt enable bit.
ES
IE.4
SPI and UART interrupt enable bit.
ET1
IE.3
Timer 1 interrupt enable bit.
EX1
IE.2
External interrupt 1 enable bit.
ET0
IE.1
Timer 0 interrupt enable bit.
EX0
IE.0
External interrupt 0 enable bit.
User software should never write 1s to unimplemented bits, because they may be used in future AT89 products.
Figure 10. Interrupt Sources
20
AT89S8252
0401F–MICRO–11/03
AT89S8252
Oscillator
Characteristics
XTAL1 and XTAL2 are the input and output, respectively, of an inverting amplifier that
can be configured for use as an on-chip oscillator, as shown in Figure 11. Either a
quartz crystal or ceramic resonator may be used. To drive the device from an external
clock source, XTAL2 should be left unconnected while XTAL1 is driven, as shown in
Figure 12. There are no requirements on the duty cycle of the external clock signal,
since the input to the internal clocking circuitry is through a divide-by-two flip-flop, but
minimum and maximum voltage high and low time specifications must be observed.
Figure 11. Oscillator Connections
Note:
C1, C2 =
=
30 pF ± 10 pF for Crystals
40 pF ± 10 pF for Ceramic Resonators
Figure 12. External Clock Drive Configuration
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0401F–MICRO–11/03
Idle Mode
In idle mode, the CPU puts itself to sleep while all the on-chip peripherals remain active.
The mode is invoked by software. The content of the on-chip RAM and all the special
functions registers remain unchanged during this mode. The idle mode can be terminated by any enabled interrupt or by a hardware reset.
Note that when idle mode is terminated by a hardware reset, the device normally
resumes program execution from where it left off, up to two machine cycles before the
internal reset algorithm takes control. On-chip hardware inhibits access to internal RAM
in this event, but access to the port pins is not inhibited. To eliminate the possibility of an
unexpected write to a port pin when idle mode is terminated by a reset, the instruction
following the one that invokes idle mode should not write to a port pin or to external
memory.
Status of External Pins During Idle and Power-down Modes
Mode
Power-down Mode
Program
Memory
ALE
PSEN
PORT0
PORT1
PORT2
PORT3
Idle
Internal
1
1
Data
Data
Data
Data
Idle
External
1
1
Float
Data
Address
Data
Power-down
Internal
0
0
Data
Data
Data
Data
Power-down
External
0
0
Float
Data
Data
Data
In the power-down mode, the oscillator is stopped and the instruction that invokes
power-down is the last instruction executed. The on-chip RAM and Special Function
Registers retain their values until the power-down mode is terminated. Exit from powerdown can be initiated either by a hardware reset or by an enabled external interrupt.
Reset redefines the SFRs but does not change the on-chip RAM. The reset should not
be activated before VCC is restored to its normal operating level and must be held active
long enough to allow the oscillator to restart and stabilize.
To exit power-down via an interrupt, the external interrupt must be enabled as level sensitive before entering power-down. The interrupt service routine starts at 16 ms
(nominal) after the enabled interrupt pin is activated.
Program Memory
Lock Bits
The AT89S8252 has three lock bits that can be left unprogrammed (U) or can be programmed (P) to obtain the additional features listed in the following table.
When lock bit 1 is programmed, the logic level at the EA pin is sampled and latched during reset. If the device is powered up without a reset, the latch initializes to a random
value and holds that value until reset is activated. The latched value of EA must agree
with the current logic level at that pin in order for the device to function properly.
Once programmed, the lock bits can only be unprogrammed with the Chip Erase operations in either the parallel or serial modes.
Lock Bit Protection Modes(1)(2)
Program Lock Bits
LB1
LB2
LB3
1
U
U
U
No internal memory lock feature.
2
P
U
U
MOVC instructions executed from external program memory are disabled from fetching code bytes from
internal memory. EA is sampled and latched on reset and further programming of the Flash memory
(parallel or serial mode) is disabled.
3
P
P
U
Same as Mode 2, but parallel or serial verify are also disabled.
P
P
P
Same as Mode 3, but external execution is also disabled.
4
Notes:
22
Protection Type
1. U = Unprogrammed
2. P = Programmed
AT89S8252
0401F–MICRO–11/03
AT89S8252
Programming the
Flash and EEPROM
Atmel’s AT89S8252 Flash Microcontroller offers 8K bytes of in-system reprogrammable
Flash Code memory and 2K bytes of EEPROM Data memory.
The AT89S8252 is normally shipped with the on-chip Flash Code and EEPROM Data
memory arrays in the erased state (i.e. contents = FFH) and ready to be programmed.
This device supports a High-voltage (12-V VPP) Parallel programming mode and a Lowvoltage (5-V VCC) Serial programming mode. The serial programming mode provides a
convenient way to reprogram the AT89S8252 inside the user’s system. The parallel programming mode is compatible with conventional third party Flash or EPROM
programmers.
The Code and Data memory arrays are mapped via separate address spaces in the
serial programming mode. In the parallel programming mode, the two arrays occupy
one contiguous address space: 0000H to 1FFFH for the Code array and 2000H to
27FFH for the Data array.
The Code and Data memory arrays on the AT89S8252 are programmed byte-by-byte in
either programming mode. An auto-erase cycle is provided with the self-timed programming operation in the serial programming mode. There is no need to perform the Chip
Erase operation to reprogram any memory location in the serial programming mode
unless any of the lock bits have been programmed.
In the parallel programming mode, there is no auto-erase cycle. To reprogram any nonblank byte, the user needs to use the Chip Erase operation first to erase both arrays.
Parallel Programming Algorithm: To program and verify the AT89S8252 in the parallel programming mode, the following sequence is recommended:
1. Power-up sequence:
Apply power between VCC and GND pins.
Set RST pin to “H”.
Apply a 3 MHz to 24 MHz clock to XTAL1 pin and wait for at least 10 milliseconds.
2. Set PSEN pin to “L”
ALE pin to “H”
EA pin to “H” and all other pins to “H”.
3. Apply the appropriate combination of “H” or “L” logic levels to pins P2.6, P2.7, P3.6,
P3.7 to select one of the programming operations shown in the Flash Programming
Modes table.
4. Apply the desired byte address to pins P1.0 to P1.7 and P2.0 to P2.5.
Apply data to pins P0.0 to P0.7 for Write Code operation.
5. Raise EA/VPP to 12V to enable Flash programming, erase or verification.
6. Pulse ALE/PROG once to program a byte in the Code memory array, the Data memory array or the lock bits. The byte-write cycle is self-timed and typically takes
1.5 ms.
7. To verify the byte just programmed, bring pin P2.7 to “L” and read the programmed
data at pins P0.0 to P0.7.
8. Repeat steps 3 through 7 changing the address and data for the entire 2K or 8K
bytes array or until the end of the object file is reached.
9. Power-off sequence:
Set XTAL1 to “L”.
Set RST and EA pins to “L”.
Turn VCC power off.
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0401F–MICRO–11/03
In the parallel programming mode, there is no auto-erase cycle and to reprogram any
non-blank byte, the user needs to use the Chip Erase operation first to erase both
arrays.
Data Polling: The AT89S8252 features DATA Polling to indicate the end of a byte write
cycle. During a byte write cycle in the parallel or serial programming mode, an
attempted read of the last byte written will result in the complement of the written datum
on P0.7 (parallel mode), and on the MSB of the serial output byte on MISO (serial
mode). Once the write cycle has been completed, true data are valid on all outputs, and
the next cycle may begin. DATA Polling may begin any time after a write cycle has been
initiated.
Ready/Busy: The progress of byte programming in the parallel programming mode can
also be monitored by the RDY/BSY output signal. Pin P3.4 is pulled Low after ALE goes
High during programming to indicate BUSY. P3.4 is pulled High again when programming is done to indicate READY.
Program Verify: If lock bits LB1 and LB2 have not been programmed, the programmed
Code or Data byte can be read back via the address and data lines for verification. The
state of the lock bits can also be verified directly in the parallel programming mode. In
the serial programming mode, the state of the lock bits can only be verified indirectly by
observing that the lock bit features are enabled.
Chip Erase: Both Flash and EEPROM arrays are erased electrically at the same time.
In the parallel programming mode, chip erase is initiated by using the proper combination of control signals and by holding ALE/PROG low for 10 ms. The Code and Data
arrays are written with all “1”s in the Chip Erase operation.
In the serial programming mode, a chip erase operation is initiated by issuing the Chip
Erase instruction. In this mode, chip erase is self-timed and takes about 16 ms.
During chip erase, a serial read from any address location will return 00H at the data
outputs.
Serial Programming Fuse: A programmable fuse is available to disable Serial Programming if the user needs maximum system security. The Serial Programming Fuse
can only be programmed or erased in the Parallel Programming Mode.
The AT89S8252 is shipped with the Serial Programming Mode enabled.
Reading the Signature Bytes: The signature bytes are read by the same procedure as
a normal verification of locations 030H and 031H, except that P3.6 and P3.7 must be
pulled to a logic low. The values returned are as follows:
(030H) = 1EH indicates manufactured by Atmel
(031H) = 72H indicates 89S8252
Programming
Interface
Every code byte in the Flash and EEPROM arrays can be written, and the entire array
can be erased, by using the appropriate combination of control signals. The write operation cycle is self-timed and once initiated, will automatically time itself to completion.
Most worldwide major programming vendors offer support for the Atmel AT89 microcontroller series. Please contact your local programming vendor for the appropriate
software revision.
24
AT89S8252
0401F–MICRO–11/03
AT89S8252
Serial Downloading
Both the Code and Data memory arrays can be programmed using the serial SPI bus
while RST is pulled to VCC. The serial interface consists of pins SCK, MOSI (input) and
MISO (output). After RST is set high, the Programming Enable instruction needs to be
executed first before program/erase operations can be executed.
An auto-erase cycle is built into the self-timed programming operation (in the serial
mode ONLY) and there is no need to first execute the Chip Erase instruction unless any
of the lock bits have been programmed. The Chip Erase operation turns the content of
every memory location in both the Code and Data arrays into FFH.
The Code and Data memory arrays have separate address spaces:
0000H to 1FFFH for Code memory and 000H to 7FFH for Data memory.
Either an external system clock is supplied at pin XTAL1 or a crystal needs to be connected across pins XTAL1 and XTAL2. The maximum serial clock (SCK) frequency
should be less than 1/40 of the crystal frequency. With a 24 MHz oscillator clock, the
maximum SCK frequency is 600 kHz.
Serial Programming
Algorithm
To program and verify the AT89S8252 in the serial programming mode, the following
sequence is recommended:
1. Power-up sequence:
Apply power between VCC and GND pins.
Set RST pin to “H”.
If a crystal is not connected across pins XTAL1 and XTAL2, apply a 3 MHz to
24 MHz clock to XTAL1 pin and wait for at least 10 milliseconds.
2. Enable serial programming by sending the Programming Enable serial instruction to
pin MOSI/P1.5. The frequency of the shift clock supplied at pin SCK/P1.7 needs to
be less than the CPU clock at XTAL1 divided by 40.
3. The Code or Data array is programmed one byte at a time by supplying the address
and data together with the appropriate Write instruction. The selected memory location is first automatically erased before new data is written. The write cycle is selftimed and typically takes less than 2.5 ms at 5V.
4. Any memory location can be verified by using the Read instruction which returns the
content at the selected address at serial output MISO/P1.6.
5. At the end of a programming session, RST can be set low to commence normal
operation.
6. Power-off sequence (if needed):
Set XTAL1 to “L” (if a crystal is not used).
Set RST to “L”.
Turn VCC power off.
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0401F–MICRO–11/03
Serial Programming
Instruction
The Instruction Set for Serial Programming follows a 3-byte protocol and is shown in the
following table:
Instruction Set
Input Format
Instruction
Byte 1
Byte 2
Byte 3
Programming Enable
1010 1100
0101 0011
xxxx xxxx
Enable serial programming interface after RST goes high.
Chip Erase
1010 1100
xxxx x100
xxxx xxxx
Chip erase both 8K & 2K memory arrays.
Read Code Memory
aaaa a001
low addr
xxxx xxxx
Read data from Code memory array at the selected address.
The 5 MSBs of the first byte are the high order address bits.
The low order address bits are in the second byte. Data are
available at pin MISO during the third byte.
Write Code Memory
aaaa a010
low addr
data in
Write data to Code memory location at selected address. The
address bits are the 5 MSBs of the first byte together with the
second byte.
Read Data Memory
00aa a101
low addr
xxxx xxxx
Read data from Data memory array at selected address. Data
are available at pin MISO during the third byte.
Write Data Memory
00aa a110
low addr
data in
Write Lock Bits
1010 1100
Notes:
26
Write data to Data memory location at selected address.
Write lock bits.
Set LB1, LB2 or LB3 = “0” to program lock bits.
1. DATA polling is used to indicate the end of a byte write cycle which typically takes less than 2.5 ms at 5V.
2. “aaaaa” = high order address.
3. “x” = don’t care.
LB1
LB2
LB3
x x111
Operation
xxxx xxxx
AT89S8252
0401F–MICRO–11/03
AT89S8252
Flash and EEPROM Parallel Programming Modes
P2.6
P2.7
P3.6
P3.7
Data I/O
P0.7:0
Address
P2.5:0 P1.7:0
12V
H
L
L
L
X
X
12V
L
H
H
H
DIN
ADDR
12V
L
L
H
H
DOUT
ADDR
12V
H
L
H
L
DIN
X
Bit - 1
P0.7 = 0
X
Bit - 2
P0.6 = 0
X
Bit - 3
P0.5 = 0
X
DOUT
X
Bit - 1
@P0.2
X
Bit - 2
@P0.1
X
Bit - 3
@P0.0
X
Mode
RST
PSEN
ALE/PROG
EA/VPP
Serial Prog. Modes
H
h(1)
h(1)
x
Chip Erase
H
L
Write (10K bytes) Memory
H
L
Read (10K bytes) Memory
H
L
Write Lock Bits:
H
L
Read Lock Bits:
H
L
(2)
H
H
12V
H
H
L
L
Read Atmel Code
H
L
H
12V
L
L
L
L
DOUT
30H
Read Device Code
H
L
H
12V
L
L
L
L
DOUT
31H
Serial Prog. Enable
H
L
(2)
12V
L
H
L
H
P0.0 = 0
X
Serial Prog. Disable
H
L
(2)
12V
L
H
L
H
P0.0 = 1
X
Read Serial Prog. Fuse
H
L
12V
H
H
L
H
@P0.0
X
Notes:
H
1. “h” = weakly pulled “High” internally.
2. Chip Erase and Serial Programming Fuse require a 10 ms PROG pulse. Chip Erase needs to be performed first before
reprogramming any byte with a content other than FFH.
3. P3.4 is pulled Low during programming to indicate RDY/BSY.
4. “X” = don’t care
27
0401F–MICRO–11/03
Figure 13. Programming the Flash/EEPROM Memory
Figure 15. Flash/EEPROM Serial Downloading
+4.0V to 6.0V
+5V
AT89S52
AT89S8252
A0 - A7
ADDR.
0000H/27FFH
VCC
VCC
P1
P2.0 - P2.5
PGM
DATA
P0
A8 - A13
P2.6
SEE FLASH
PROGRAMMING
MODES TABLE
P2.7
ALE
PROG
P3.6
INSTRUCTION
INPUT
P1.5/MOSI
DATA OUTPUT
P1.6/MISO
CLOCK IN
P1.7/SCK
P3.7
XTAL2
EA
XTAL2
VPP
3-24 MHz
3-24 MHz
XTAL1
GND
P3.4
RDY/
BSY
RST
VIH
XTAL1
RST
VIH
GND
PSEN
Figure 14. Verifying the Flash/EEPROM Memory
+5V
AT89S8252
ADDR.
0000H/2FFFH
A0 - A7
A8 - A13
SEE FLASH
PROGRAMMING
MODES TABLE
P1
VCC
P2.0 - P2.5
P0
P2.6
P2.7
PGM DATA
(USE 10K
PULLUPS)
ALE
VI H
XTAL2
EA
VPP
XTAL1
RST
VI H
P3.6
P3.7
3-24 Mhz
GND
28
PSEN
AT89S8252
0401F–MICRO–11/03
AT89S8252
Flash Programming and Verification Characteristics – Parallel Mode
TA = 0°C to 70°C, VCC = 5.0V ± 10%
Symbol
Parameter
Min
Max
Units
VPP
Programming Enable Voltage
11.5
12.5
V
IPP
Programming Enable Current
1.0
mA
1/tCLCL
Oscillator Frequency
24
MHz
tAVGL
Address Setup to PROG Low
48tCLCL
tGHAX
Address Hold after PROG
48tCLCL
tDVGL
Data Setup to PROG Low
48tCLCL
tGHDX
Data Hold after PROG
48tCLCL
tEHSH
P2.7 (ENABLE) High to VPP
48tCLCL
tSHGL
VPP Setup to PROG Low
10
tGLGH
PROG Width
1
tAVQV
Address to Data Valid
48tCLCL
tELQV
ENABLE Low to Data Valid
48tCLCL
tEHQZ
Data Float after ENABLE
tGHBL
PROG High to BUSY Low
1.0
µs
tWC
Byte Write Cycle Time
2.0
ms
3
0
µs
110
µs
48tCLCL
Flash/EEPROM Programming and Verification Waveforms – Parallel Mode
29
0401F–MICRO–11/03
Serial Downloading Waveforms
SERIAL CLOCK INPUT
SCK/P1.7
7
6
5
4
3
2
1
0
SERIAL DATA INPUT
MOSI/P1.5
MSB
LSB
MSB
LSB
SERIAL DATA OUTPUT
MISO/P1.6
Serial Programming Characteristics
Figure 16. Serial Programming Timing
MOSI
tOVSH
SCK
tSHOX
tSLSH
tSHSL
MISO
Table 11. Serial Programming Characteristics, TA = -40° C to 85° C, VCC = 4.0 - 6.0V (Unless Otherwise Noted)
Symbol
Parameter
1/tCLCL
Oscillator Frequency
tCLCL
Oscillator Period
tSHSL
Min
0
Typ
Max
Units
24
MHz
41.6
ns
SCK Pulse Width High
24 tCLCL
ns
tSLSH
SCK Pulse Width Low
24 tCLCL
ns
tOVSH
MOSI Setup to SCK High
tCLCL
ns
tSHOX
MOSI Hold after SCK High
2 tCLCL
ns
30
AT89S8252
0401F–MICRO–11/03
AT89S8252
Z
Absolute Maximum Ratings*
Operating Temperature.................................. -55°C to +125°C
*NOTICE:
Storage Temperature ..................................... -65°C to +150°C
Voltage on Any Pin
with Respect to Ground .....................................-1.0V to +7.0V
Maximum Operating Voltage ............................................ 6.6V
Stresses beyond those listed under “Absolute
Maximum Ratings” may cause permanent damage 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.
DC Output Current...................................................... 15.0 mA
DC Characteristics
The values shown in this table are valid for TA = -40°C to 85°C and VCC = 5.0V ± 20%, unless otherwise noted.
Symbol
Parameter
Condition
Min
Max
Units
VIL
Input Low-voltage
(Except EA)
-0.5
0.2 VCC - 0.1
V
VIL1
Input Low-voltage (EA)
-0.5
0.2 VCC - 0.3
V
VIH
Input High-voltage
0.2 VCC + 0.9
VCC + 0.5
V
VIH1
Input High-voltage
0.7 VCC
VCC + 0.5
V
(Except XTAL1, RST)
(XTAL1, RST)
VOL
Output Low-voltage
(Ports 1,2,3)
(1)
IOL = 1.6 mA
0.5
V
VOL1
Output Low-voltage (1)
(Port 0, ALE, PSEN)
IOL = 3.2 mA
0.5
V
VOH
Output High-voltage
(Ports 1,2,3, ALE, PSEN)
IOH = -60 µA, VCC = 5V ± 10%
VOH1
Output High-voltage
(Port 0 in External Bus Mode)
2.4
V
IOH = -25 µA
0.75 VCC
V
IOH = -10 µA
0.9 VCC
V
2.4
V
IOH = -300 µA
0.75 VCC
V
IOH = -80 µA
0.9 VCC
V
IOH = -800 µA, VCC = 5V ± 10%
IIL
Logical 0 Input Current (Ports 1,2,3)
VIN = 0.45V
-50
µA
ITL
Logical 1 to 0 Transition Current (Ports 1,2,3)
VIN = 2V, VCC = 5V ± 10%
-650
µA
ILI
Input Leakage Current
(Port 0, EA)
0.45 < VIN < VCC
±10
µA
RRST
Reset Pull-down Resistor
300
KΩ
CIO
Pin Capacitance
Test Freq. = 1 MHz, TA = 25°C
10
pF
ICC
Power Supply Current
Active Mode, 12 MHz
25
mA
Idle Mode, 12 MHz
6.5
mA
VCC = 6V
100
µA
VCC = 3V
40
µA
Power-down Mode
Notes:
(2)
50
1. Under steady state (non-transient) conditions, IOL must be externally limited as follows:
Maximum IOL per port pin: 10 mA
Maximum IOL per 8-bit port: Port 0: 26 mA; Ports 1, 2, 3: 15 mA
Maximum total IOL for all output pins: 71 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. Minimum VCC for Power-down is 2V
31
0401F–MICRO–11/03
AC Characteristics
Under operating conditions, load capacitance for Port 0, ALE/PROG, and PSEN = 100 pF; load capacitance for all other
outputs = 80 pF.
External Program and Data Memory Characteristics
Variable Oscillator
Symbol
Parameter
1/tCLCL
Oscillator Frequency
tLHLL
ALE Pulse Width
2tCLCL - 40
ns
tAVLL
Address Valid to ALE Low
tCLCL - 13
ns
tLLAX
Address Hold after ALE Low
tCLCL - 20
ns
tLLIV
ALE Low to Valid Instruction In
tLLPL
ALE Low to PSEN Low
tCLCL - 13
ns
tPLPH
PSEN Pulse Width
3tCLCL - 20
ns
tPLIV
PSEN Low to Valid Instruction In
tPXIX
Input Instruction Hold after PSEN
tPXIZ
Input Instruction Float after PSEN
tPXAV
PSEN to Address Valid
tAVIV
Address to Valid Instruction In
tPLAZ
PSEN Low to Address Float
tRLRH
RD Pulse Width
6tCLCL - 100
ns
tWLWH
WR Pulse Width
6tCLCL - 100
ns
tRLDV
RD Low to Valid Data In
tRHDX
Data Hold after RD
tRHDZ
Data Float after RD
2tCLCL - 28
ns
tLLDV
ALE Low to Valid Data In
8tCLCL - 150
ns
tAVDV
Address to Valid Data In
9tCLCL - 165
ns
tLLWL
ALE Low to RD or WR Low
3tCLCL - 50
3tCLCL + 50
ns
tAVWL
Address to RD or WR Low
4tCLCL - 75
ns
tQVWX
Data Valid to WR Transition
tCLCL - 20
ns
tQVWH
Data Valid to WR High
7tCLCL - 120
ns
tWHQX
Data Hold after WR
tCLCL - 20
ns
tRLAZ
RD Low to Address Float
tWHLH
RD or WR High to ALE High
32
Min
Max
Units
0
24
MHz
4tCLCL - 65
3tCLCL - 45
0
ns
ns
tCLCL - 10
tCLCL - 8
ns
ns
5tCLCL - 55
ns
10
ns
5tCLCL - 90
0
tCLCL - 20
ns
ns
ns
0
ns
tCLCL + 25
ns
AT89S8252
0401F–MICRO–11/03
AT89S8252
External Program Memory Read Cycle
External Data Memory Read Cycle
33
0401F–MICRO–11/03
External Data Memory Write Cycle
External Clock Drive Waveforms
External Clock Drive
VCC = 4.0V to 6.0V
Symbol
Parameter
1/tCLCL
Oscillator Frequency
tCLCL
Clock Period
tCHCX
Min
Max
Units
0
24
MHz
41.6
ns
High Time
15
ns
tCLCX
Low Time
15
ns
tCLCH
Rise Time
20
ns
tCHCL
Fall Time
20
ns
34
AT89S8252
0401F–MICRO–11/03
AT89S8252
Serial Port Timing: Shift Register Mode Test Conditions
The values in this table are valid for VCC = 4.0V to 6V and Load Capacitance = 80 pF.
Variable Oscillator
Symbol
Parameter
tXLXL
Serial Port Clock Cycle Time
tQVXH
Output Data Setup to Clock Rising Edge
tXHQX
Output Data Hold after Clock Rising Edge
tXHDX
Input Data Hold after Clock Rising Edge
tXHDV
Clock Rising Edge to Input Data Valid
Min
Max
Units
12tCLCL
µs
10tCLCL - 133
ns
2tCLCL - 117
ns
0
ns
10tCLCL - 133
ns
Shift Register Mode Timing Waveforms
AC Testing Input/Output Waveforms(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.
Float Waveforms(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 a 100 mV change from the loaded VOH/VOL level occurs.
35
0401F–MICRO–11/03
AT89S8252
TYPICAL ICC (ACTIVE) at 25°C
24
VCC = 6.0V
20
I
C 16
C
12
m
A 8
VCC = 5.0V
4
0
0
4
8
12
16
20
24
F (MHz)
AT89S8252
TYPICAL ICC (IDLE) at 25°C
4.8
VCC = 6.0V
4.0
I
C 3.2
C 2.4
VCC = 5.0V
m 1.6
A
0.8
0.0
0
4
8
12
16
20
24
F (MHz)
Notes:
36
1. XTAL1 tied to GND for Icc (power-down)
2. Lock bits programmed
AT89S8252
0401F–MICRO–11/03
AT89S8252
Ordering Information
Speed
(MHz)
24
Power
Supply
Ordering Code
Package
Operation Range
4.0V to 6.0V
AT89S8252-24AC
AT89S8252-24JC
AT89S8252-24PC
44A
44J
40P6
Commercial
(0° C to 70° C)
4.0V to 6.0V
AT89S8252-24AI
AT89S8252-24JI
AT89S8252-24PI
44A
44J
40P6
Industrial
(-40° C to 85° C)
Package Type
44A
44-lead, Thin Plastic Gull Wing Quad Flatpack (TQFP)
44J
44-lead, Plastic J-leaded Chip Carrier (PLCC)
40P6
40-lead, 0.600" Wide, Plastic Dual Inline Package (PDIP)
37
0401F–MICRO–11/03
Packaging Information
44A – TQFP
PIN 1
B
PIN 1 IDENTIFIER
E1
e
E
D1
D
C
0˚~7˚
A1
A2
A
L
COMMON DIMENSIONS
(Unit of Measure = mm)
Notes:
1. This package conforms to JEDEC reference MS-026, Variation ACB.
2. Dimensions D1 and E1 do not include mold protrusion. Allowable
protrusion is 0.25 mm per side. Dimensions D1 and E1 are maximum
plastic body size dimensions including mold mismatch.
3. Lead coplanarity is 0.10 mm maximum.
SYMBOL
MIN
NOM
MAX
A
–
–
1.20
A1
0.05
–
0.15
A2
0.95
1.00
1.05
D
11.75
12.00
12.25
D1
9.90
10.00
10.10
E
11.75
12.00
12.25
E1
9.90
10.00
10.10
B
0.30
–
0.45
C
0.09
–
0.20
L
0.45
–
0.75
e
NOTE
Note 2
Note 2
0.80 TYP
10/5/2001
R
38
2325 Orchard Parkway
San Jose, CA 95131
TITLE
44A, 44-lead, 10 x 10 mm Body Size, 1.0 mm Body Thickness,
0.8 mm Lead Pitch, Thin Profile Plastic Quad Flat Package (TQFP)
DRAWING NO.
REV.
44A
B
AT89S8252
0401F–MICRO–11/03
AT89S8252
44J – PLCC
1.14(0.045) X 45˚
PIN NO. 1
1.14(0.045) X 45˚
0.318(0.0125)
0.191(0.0075)
IDENTIFIER
E1
D2/E2
B1
E
B
e
A2
D1
A1
D
A
0.51(0.020)MAX
45˚ MAX (3X)
COMMON DIMENSIONS
(Unit of Measure = mm)
Notes:
1. This package conforms to JEDEC reference MS-018, Variation AC.
2. Dimensions D1 and E1 do not include mold protrusion.
Allowable protrusion is .010"(0.254 mm) per side. Dimension D1
and E1 include mold mismatch and are measured at the extreme
material condition at the upper or lower parting line.
3. Lead coplanarity is 0.004" (0.102 mm) maximum.
SYMBOL
MIN
NOM
MAX
A
4.191
–
4.572
A1
2.286
–
3.048
A2
0.508
–
–
D
17.399
–
17.653
D1
16.510
–
16.662
E
17.399
–
17.653
E1
16.510
–
16.662
D2/E2
14.986
–
16.002
B
0.660
–
0.813
B1
0.330
–
0.533
e
NOTE
Note 2
Note 2
1.270 TYP
10/04/01
R
2325 Orchard Parkway
San Jose, CA 95131
TITLE
44J, 44-lead, Plastic J-leaded Chip Carrier (PLCC)
DRAWING NO.
REV.
44J
B
39
0401F–MICRO–11/03
40P6 – PDIP
D
PIN
1
E1
A
SEATING PLANE
A1
L
B
B1
e
E
0º ~ 15º
C
COMMON DIMENSIONS
(Unit of Measure = mm)
REF
MIN
NOM
MAX
A
–
–
4.826
A1
0.381
–
–
D
52.070
–
52.578
E
15.240
–
15.875
E1
13.462
–
13.970
B
0.356
–
0.559
B1
1.041
–
1.651
L
3.048
–
3.556
C
0.203
–
0.381
eB
15.494
–
17.526
SYMBOL
eB
Notes:
1. This package conforms to JEDEC reference MS-011, Variation AC.
2. Dimensions D and E1 do not include mold Flash or Protrusion.
Mold Flash or Protrusion shall not exceed 0.25 mm (0.010").
e
NOTE
Note 2
Note 2
2.540 TYP
09/28/01
R
40
2325 Orchard Parkway
San Jose, CA 95131
TITLE
40P6, 40-lead (0.600"/15.24 mm Wide) Plastic Dual
Inline Package (PDIP)
DRAWING NO.
40P6
REV.
B
AT89S8252
0401F–MICRO–11/03
Atmel Corporation
2325 Orchard Parkway
San Jose, CA 95131, USA
Tel: 1(408) 441-0311
Fax: 1(408) 487-2600
Regional Headquarters
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Atmel Sarl
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Tel: (81) 3-3523-3551
Fax: (81) 3-3523-7581
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Disclaimer: Atmel Corporation makes no warranty for the use of its products, other than those expressly contained in the Company’s standard
warranty which is detailed in Atmel’s Terms and Conditions located on the Company’s web site. The Company assumes no responsibility for any
errors which may appear in this document, reserves the right to change devices or specifications detailed herein at any time without notice, and
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subsidiaries. MCS ® is a registered trademark of Intel Corporation. Other terms and product names may be the trademarks of others.
Printed on recycled paper.
0401F–MICRO–11/03
xM