Features • Compatible with MCS®-51 Products (cid:129) 8K Bytes of In-System Programmable (ISP) Flash Memory – Endurance: 10,000 Write/Erase Cycles (cid:129) 4.0V to 5.5V Operating Range (cid:129) Fully Static Operation: 0 Hz to 33 MHz (cid:129) Three-level Program Memory Lock (cid:129) 256 x 8-bit Internal RAM (cid:129) 32 Programmable I/O Lines 8-bit (cid:129) Three 16-bit Timer/Counters (cid:129) Eight Interrupt Sources Microcontroller (cid:129) Full Duplex UART Serial Channel (cid:129) Low-power Idle and Power-down Modes with 8K Bytes (cid:129) Interrupt Recovery from Power-down Mode (cid:129) Watchdog Timer In-System (cid:129) Dual Data Pointer (cid:129) Power-off Flag Programmable (cid:129) Fast Programming Time Flash (cid:129) Flexible ISP Programming (Byte and Page Mode) (cid:129) Green (Pb/Halide-free) Packaging Option AT89S52 1. Description The AT89S52 is a low-power, high-performance CMOS 8-bit microcontroller with 8K bytes of in-system programmable Flash memory. The device is manufactured using Atmel’s high-density nonvolatile memory technology and is compatible with the indus- try-standard 80C51 instruction set and pinout. The on-chip Flash allows the program memory to be reprogrammed in-system or by a conventional nonvolatile memory pro- grammer. By combining a versatile 8-bit CPU with in-system programmable Flash on a monolithic chip, the Atmel AT89S52 is a powerful microcontroller which provides a highly-flexible and cost-effective solution to many embedded control applications. The AT89S52 provides the following standard features: 8K bytes of Flash, 256 bytes of RAM, 32 I/O lines, 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 AT89S52 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 con- tents but freezes the oscillator, disabling all other chip functions until the next interrupt or hardware reset. 1919D–MICRO–6/08

2. Pin Configurations 2.1 40-lead PDIP 2.3 44-lead PLCC X) (T2) P1.0 1 40 VCC T2 ET2) AD0)AD1)AD2)AD3) (T2 EX) P1.1 2 39 P0.0 (AD0) 4 321 (0 ( C0 (1 (2 (3 ( 1.1.1.1.1.CC0.0.0.0. P1.2 3 38 P0.1 (AD1) PPPPPNVPPPP P1.3 4 37 P0.2 (AD2) 65432143210 P1.4 5 36 P0.3 (AD3) (MOSI) P1.5 7 4444439 P0.4 (AD4) (MOSI) P1.5 6 35 P0.4 (AD4) (MISO) P1.6 8 38 P0.5 (AD5) (MISO) P1.6 7 34 P0.5 (AD5) (SCK) P1.7 9 37 P0.6 (AD6) (SCK) P1.7 8 33 P0.6 (AD6) RST 10 36 P0.7 (AD7) (RXD) P3.0 11 35 EA/VPP RST 9 32 P0.7 (AD7) NC 12 34 NC (RXD) P3.0 10 31 EA/VPP (TXD) P3.1 13 33 ALE/PROG (TXD) P3.1 11 30 ALE/PROG (INT0) P3.2 14 32 PSEN (INT0) P3.2 12 29 PSEN (INT1) P3.3 15 31 P2.7 (A15) (INT1) P3.3 13 28 P2.7 (A15) (T0) P3.4 16 30 P2.6 (A14) (T0) P3.4 14 27 P2.6 (A14) (T1) P3.5 17 29 P2.5 (A13) 89012345678 (T1) P3.5 15 26 P2.5 (A13) 11222222222 (WR) P3.6 16 25 P2.4 (A12) 6721DC01234 (RDX)T PA3L.72 1178 2243 PP22..32 ((AA1110)) R) P3.D) P3.XTALXTALGNN8) P2.9) P2.0) P2.1) P2.2) P2. XTAL1 19 22 P2.1 (A9) (W(R (A(A(A1(A1(A1 GND 20 21 P2.0 (A8) 2.2 44-lead TQFP X) 2 E2) D0)D1)D2)D3) TT AAAA 4321 (0 ( C0 (1 (2 (3 ( 1.1.1.1.1.CC0.0.0.0. PPPPPNVPPPP 43210987654 44444333333 (MOSI) P1.5 1 33 P0.4 (AD4) (MISO) P1.6 2 32 P0.5 (AD5) (SCK) P1.7 3 31 P0.6 (AD6) RST 4 30 P0.7 (AD7) (RXD) P3.0 5 29 EA/VPP NC 6 28 NC (TXD) P3.1 7 27 ALE/PROG (INT0) P3.2 8 26 PSEN (INT1) P3.3 9 25 P2.7 (A15) (T0) P3.4 10 24 P2.6 (A14) (T1) P3.5 11 23 P2.5 (A13) 23456789012 11111111222 6721DD01234 R) P3.D) P3.XTALXTALGNGN8) P2.9) P2.0) P2.1) P2.2) P2. (W(R (A(A(A1(A1(A1 AT89S52 2 1919D–MICRO–6/08

AT89S52 3. Block Diagram P0.0 - P0.7 P2.0 - P2.7 V CC PORT 0 DRIVERS PORT 2 DRIVERS GND RAM ADDR. PORT 0 PORT 2 REGISTER RAM LATCH LATCH FLASH PROGRAM B STACK REGISTER ACC POINTER ADDRESS REGISTER BUFFER TMP2 TMP1 PC ALU INCREMENTER INTERRUPT, SERIAL PORT, AND TIMER BLOCKS PROGRAM PSW COUNTER PSEN ALE/PROG TIMING INSTRUCTION AND DUAL DPTR REGISTER EA / V CONTROL PP RST WATCH PORT 3 PORT 1 ISP PROGRAM DOG LATCH LATCH PORT LOGIC OSC PORT 3 DRIVERS PORT 1 DRIVERS P3.0 - P3.7 P1.0 - P1.7 3 1919D–MICRO–6/08

4. Pin Description 4.1 VCC Supply voltage. 4.2 GND Ground. 4.3 Port 0 Port 0 is an 8-bit open drain bidirectional 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 high-impedance 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 dur- ing program verification. External pull-ups are required during program verification. 4.4 Port 1 Port 1 is an 8-bit bidirectional 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 inter- nal pull-ups and can be used as inputs. As inputs, Port 1 pins that are externally being pulled low will source current (I ) because of the internal pull-ups. IL In addition, 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, as shown in the follow- ing table. Port 1 also receives the low-order address bytes during Flash programming and verification. 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) P1.5 MOSI (used for In-System Programming) P1.6 MISO (used for In-System Programming) P1.7 SCK (used for In-System Programming) 4.5 Port 2 Port 2 is an 8-bit bidirectional 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 inter- nal pull-ups and can be used as inputs. As inputs, Port 2 pins that are externally being pulled low will source current (I ) because of the internal pull-ups. IL Port 2 emits the high-order address byte during fetches from external program memory and dur- ing 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 program- ming and verification. AT89S52 4 1919D–MICRO–6/08

AT89S52 4.6 Port 3 Port 3 is an 8-bit bidirectional 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 inter- nal pull-ups and can be used as inputs. As inputs, Port 3 pins that are externally being pulled low will source current (I ) because of the pull-ups. IL Port 3 receives some control signals for Flash programming and verification. Port 3 also serves the functions of various special features of the AT89S52, as shown in the fol- lowing table. 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) 4.7 RST Reset input. A high on this pin for two machine cycles while the oscillator is running resets the device. This pin drives high for 98 oscillator periods after the Watchdog times out. The DISRTO bit in SFR AUXR (address 8EH) can be used to disable this feature. In the default state of bit DISRTO, the RESET HIGH out feature is enabled. 4.8 ALE/PROG Address Latch Enable (ALE) 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 dur- ing 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. 5 1919D–MICRO–6/08

4.9 PSEN Program Store Enable (PSEN) is the read strobe to external program memory. When the AT89S52 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 exter- nal data memory. 4.10 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 V for internal program executions. CC This pin also receives the 12-volt programming enable voltage (V ) during Flash programming. PP 4.11 XTAL1 Input to the inverting oscillator amplifier and input to the internal clock operating circuit. 4.12 XTAL2 Output from the inverting oscillator amplifier. 5. Special Function Registers A map of the on-chip memory area called the Special Function Register (SFR) space is shown in Table 5-1. 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 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 5- 2) and T2MOD (shown in Table 10-2) 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. Interrupt Registers: The individual interrupt enable bits are in the IE register. Two priorities can be set for each of the six interrupt sources in the IP register. AT89S52 6 1919D–MICRO–6/08

AT89S52 Table 5-1. AT89S52 SFR Map and Reset Values 0F8H 0FFH B 0F0H 0F7H 00000000 0E8H 0EFH ACC 0E0H 0E7H 00000000 0D8H 0DFH PSW 0D0H 0D7H 00000000 T2CON T2MOD RCAP2L RCAP2H TL2 TH2 0C8H 0CFH 00000000 XXXXXX00 00000000 00000000 00000000 00000000 0C0H 0C7H IP 0B8H 0BFH XX000000 P3 0B0H 0B7H 11111111 IE 0A8H 0AFH 0X000000 P2 AUXR1 WDTRST 0A0H 0A7H 11111111 XXXXXXX0 XXXXXXXX SCON SBUF 98H 9FH 00000000 XXXXXXXX P1 90H 97H 11111111 TCON TMOD TL0 TL1 TH0 TH1 AUXR 88H 8FH 00000000 00000000 00000000 00000000 00000000 00000000 XXX00XX0 P0 SP DP0L DP0H DP1L DP1H PCON 80H 87H 11111111 00000111 00000000 00000000 00000000 00000000 0XXX0000 7 1919D–MICRO–6/08

Table 5-2. T2CON – Timer/Counter 2 Control Register T2CON Address = 0C8H Reset Value = 0000 0000B Bit Addressable TF2 EXF2 RCLK TCLK EXEN2 TR2 C/T2 CP/RL2 Bit 7 6 5 4 3 2 1 0 Symbol Function 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 TF2 or TCLK = 1. Timer 2 external flag set when either a capture or reload is caused by a negative transition on T2EX and EXEN2 = 1. EXF2 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). Receive clock enable. When set, causes the serial port to use Timer 2 overflow pulses for its receive clock in serial port RCLK Modes 1 and 3. RCLK = 0 causes Timer 1 overflow to be used for the receive clock. Transmit clock enable. When set, causes the serial port to use Timer 2 overflow pulses for its transmit clock in serial port TCLK Modes 1 and 3. TCLK = 0 causes Timer 1 overflows to be used for the transmit clock. Timer 2 external enable. When set, allows a capture or reload to occur as a result of a negative transition on T2EX if Timer EXEN2 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). Capture/Reload select. CP/RL2 = 1 causes captures to occur on negative transitions at T2EX if EXEN2 = 1. CP/RL2 = 0 CP/RL2 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. AT89S52 8 1919D–MICRO–6/08

AT89S52 Table 5-3. AUXR: Auxiliary Register AUXR Address = 8EH Reset Value = XXX00XX0B Not Bit Addressable – – – WDIDLE DISRTO – – DISALE Bit 7 6 5 4 3 2 1 0 – Reserved for future expansion DISALE Disable/Enable ALE DISALE Operating Mode 0 ALE is emitted at a constant rate of 1/6 the oscillator frequency 1 ALE is active only during a MOVX or MOVC instruction DISRTO Disable/Enable Reset out DISRTO 0 Reset pin is driven High after WDT times out 1 Reset pin is input only WDIDLE Disable/Enable WDT in IDLE mode WDIDLE 0 WDT continues to count in IDLE mode 1 WDT halts counting in IDLE mode Dual Data Pointer Registers: To facilitate accessing both internal 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 AUXR1 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 rest under software control and is not affected by reset. Table 5-4. AUXR1: Auxiliary Register 1 AUXR1 Address = A2H Reset Value = XXXXXXX0B Not Bit Addressable – – – – – – – DPS Bit 7 6 5 4 3 2 1 0 – Reserved for future expansion DPS Data Pointer Register Select DPS 0 Selects DPTR Registers DP0L, DP0H 1 Selects DPTR Registers DP1L, DP1H 9 1919D–MICRO–6/08

6. Memory Organization MCS-51 devices have a separate address space for Program and Data Memory. Up to 64K bytes each of external Program and Data Memory can be addressed. 6.1 Program Memory If the EA pin is connected to GND, all program fetches are directed to external memory. On the AT89S52, if EA is connected to V , program fetches to addresses 0000H through CC 1FFFH are directed to internal memory and fetches to addresses 2000H through FFFFH are to external memory. 6.2 Data Memory The AT89S52 implements 256 bytes of on-chip RAM. The upper 128 bytes occupy a parallel address space to the Special Function Registers. This means that 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 which use direct addressing access the 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. 7. Watchdog Timer (One-time Enabled with Reset-out) The WDT is intended as a recovery method in situations where the CPU may be subjected to software upsets. The WDT consists of a 14-bit counter and the Watchdog Timer Reset (WDTRST) SFR. The WDT is defaulted to disable from exiting reset. To enable the WDT, a user must write 01EH and 0E1H in sequence to the WDTRST register (SFR location 0A6H). When the WDT is enabled, it will increment every machine cycle while the oscillator is running. The WDT timeout period is dependent on the external clock frequency. There is no way to disable the WDT except through reset (either hardware reset or WDT overflow reset). When WDT over- flows, it will drive an output RESET HIGH pulse at the RST pin. 7.1 Using the WDT To enable the WDT, a user must write 01EH and 0E1H in sequence to the WDTRST register (SFR location 0A6H). When the WDT is enabled, the user needs to service it by writing 01EH and 0E1H to WDTRST to avoid a WDT overflow. The 14-bit counter overflows when it reaches 16383 (3FFFH), and this will reset the device. When the WDT is enabled, it will increment every machine cycle while the oscillator is running. This means the user must reset the WDT at least every 16383 machine cycles. To reset the WDT the user must write 01EH and 0E1H to WDTRST. WDTRST is a write-only register. The WDT counter cannot be read or written. When AT89S52 10 1919D–MICRO–6/08

AT89S52 WDT overflows, it will generate an output RESET pulse at the RST pin. The RESET pulse dura- tion is 98xTOSC, where TOSC = 1/FOSC. To make the best use of the WDT, it should be serviced in those sections of code that will periodically be executed within the time required to prevent a WDT reset. 7.2 WDT During Power-down and Idle In Power-down mode the oscillator stops, which means the WDT also stops. While in Power- down mode, the user does not need to service the WDT. There are two methods of exiting Power-down mode: by a hardware reset or via a level-activated external interrupt which is enabled prior to entering Power-down mode. When Power-down is exited with hardware reset, servicing the WDT should occur as it normally does whenever the AT89S52 is reset. Exiting Power-down with an interrupt is significantly different. The interrupt is held low long enough for the oscillator to stabilize. When the interrupt is brought high, the interrupt is serviced. To prevent the WDT from resetting the device while the interrupt pin is held low, the WDT is not started until the interrupt is pulled high. It is suggested that the WDT be reset during the interrupt service for the interrupt used to exit Power-down mode. To ensure that the WDT does not overflow within a few states of exiting Power-down, it is best to reset the WDT just before entering Power-down mode. Before going into the IDLE mode, the WDIDLE bit in SFR AUXR is used to determine whether the WDT continues to count if enabled. The WDT keeps counting during IDLE (WDIDLE bit = 0) as the default state. To prevent the WDT from resetting the AT89S52 while in IDLE mode, the user should always set up a timer that will periodically exit IDLE, service the WDT, and reenter IDLE mode. With WDIDLE bit enabled, the WDT will stop to count in IDLE mode and resumes the count upon exit from IDLE. 8. UART The UART in the AT89S52 operates the same way as the UART in the AT89C51 and AT89C52. For further information on the UART operation, please click on the document link below: http://www.atmel.com/dyn/resources/prod_documents/DOC4316.PDF 9. Timer 0 and 1 Timer 0 and Timer 1 in the AT89S52 operate the same way as Timer 0 and Timer 1 in the AT89C51 and AT89C52. For further information on the timers’ operation, please click on the document link below: http://www.atmel.com/dyn/resources/prod_documents/DOC4316.PDF 11 1919D–MICRO–6/08

10. 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 5-2). 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 10-1. 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 oscil- lator frequency. Table 10-1. Timer 2 Operating Modes 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 Counter function, the register is incremented in response to a 1-to-0 transition at its corre- sponding 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. 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. 10.1 Capture Mode 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 1-to-0 transi- tion 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 illus- trated in Figure 10-1. 10.2 Auto-reload (Up or Down Counter) Timer 2 can be programmed to count up or down when configured in its 16-bit auto-reload mode. This feature is invoked by the DCEN (Down Counter Enable) bit located in the SFR T2MOD (see Table 10-2). 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. AT89S52 12 1919D–MICRO–6/08

AT89S52 Figure 10-1. Timer in Capture Mode OSC ÷12 C/T2 = 0 TH2 TL2 TF2 OVERFLOW CONTROL TR2 C/T2 = 1 T2 PIN CAPTURE RCAP2H RCAP2L TRANSITION TIMER 2 DETECTOR INTERRUPT T2EX PIN EXF2 CONTROL EXEN2 Table 10-2. T2MOD – Timer 2 Mode Control Register T2MOD Address = 0C9H Reset Value = XXXX XX00B Not Bit Addressable – – – – – – T2OE DCEN Bit 7 6 5 4 3 2 1 0 Symbol Function – Not implemented, reserved for future T2OE Timer 2 Output Enable bit DCEN When set, this bit allows Timer 2 to be configured as an up/down counter Figure 10-2 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 Timer in Capture ModeRCAP2H 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 10-2. 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. 13 1919D–MICRO–6/08

Figure 10-2. Timer 2 Auto Reload Mode (DCEN = 0) OSC ÷12 C/T2 = 0 TH2 TL2 CONTROL OVERFLOW TR2 C/T2 = 1 RELOAD T2 PIN TIMER 2 INTERRUPT RCAP2H RCAP2L TF2 TRANSITION DETECTOR T2EX PIN EXF2 CONTROL EXEN2 Figure 10-3. Timer 2 Auto Reload Mode (DCEN = 1) (DOWN COUNTING RELOAD VALUE) TOGGLE 0FFH 0FFH EXF2 OSC ÷12 OVERFLOW C/T2 = 0 TH2 TL2 TF2 CONTROL TR2 TIMER 2 C/T2 = 1 INTERRUPT T2 PIN RCAP2H RCAP2L COUNT (UP COUNTING RELOAD VALUE) DIRECTION 1=UP 0=DOWN T2EX PIN AT89S52 14 1919D–MICRO–6/08

AT89S52 11. Baud Rate Generator Timer 2 is selected as the baud rate generator by setting TCLK and/or RCLK in T2CON (Table 5-2). 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 11-1. 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 fol- lowing equation. Timer 2 Overflow Rate Modes 1 and 3 Baud Rates = ------------------------------------------------------------ 16 The Timer can be configured for either timer or counter operation. In most applications, it is con- figured 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 x [65536-RCAP2H,RCAP2L)] where (RCAP2H, RCAP2L) is the content of RCAP2H and RCAP2L taken as a 16-bit unsigned integer. Timer 2 as a baud rate generator is shown in Figure 11-1. 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 inter- rupt. 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. 15 1919D–MICRO–6/08

Figure 11-1. 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" "0" TH2 TL2 RCLK Rx CONTROL CLOCK ÷16 TR2 C/T2 = 1 "1" "0" T2 PIN TCLK RCAP2H RCAP2L Tx CLOCK TRANSITION ÷16 DETECTOR TIMER 2 T2EX PIN EXF2 INTERRUPT CONTROL EXEN2 12. Programmable Clock Out A 50% duty cycle clock can be programmed to come out on P1.0, as shown in Figure 12-1. This pin, besides being a regular I/O 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 x [65536-(RCAP2H,RCAP2L)] In the clock-out mode, Timer 2 roll-overs 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 gen- erator 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. AT89S52 16 1919D–MICRO–6/08

AT89S52 Figure 12-1. Timer 2 in Clock-Out Mode TL2 TH2 OSC ÷2 (8-BITS) (8-BITS) TR2 RCAP2L RCAP2H C/T2 BIT P1.0 ÷2 (T2) T2OE (T2MOD.1) TRANSITION DETECTOR (T2PE1X.1) EXF2 TINIMTEERRR U2PT EXEN2 13. Interrupts The AT89S52 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 13-1. 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 13-1 shows that bit position IE.6 is unimplemented. User software should not write a 1 to this bit position, since it may be used in future AT89 products. Timer 2 interrupt is generated by the logical OR of bits TF2 and EXF2 in register T2CON. Nei- ther 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. 17 1919D–MICRO–6/08

Table 13-1. 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 Disables all interrupts. If EA = 0, no interrupt is acknowledged. If EA = 1, each EA IE.7 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 Serial Port 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 reserved bits, because they may be used in future AT89 products. Figure 13-1. Interrupt Sources 0 INT0 IE0 1 TF0 0 INT1 IE1 1 TF1 TI RI TF2 EXF2 AT89S52 18 1919D–MICRO–6/08

AT89S52 14. 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 16-1. 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 16-2. There are no requirements on the duty cycle of the external clock signal, since the input to the internal clock- ing circuitry is through a divide-by-two flip-flop, but minimum and maximum voltage high and low time specifications must be observed. 15. 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 regis- ters 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 pro- gram 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. 16. Power-down Mode 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 Power-down mode 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 V is restored to CC its normal operating level and must be held active long enough to allow the oscillator to restart and stabilize. Figure 16-1. Oscillator Connections C2 XTAL2 C1 XTAL1 GND Note: 1. C1, C2 = 30 pF ± 10 pF for Crystals = 40 pF ± 10 pF for Ceramic Resonators 19 1919D–MICRO–6/08

Figure 16-2. External Clock Drive Configuration NC XTAL2 EXTERNAL OSCILLATOR XTAL1 SIGNAL GND Table 16-1. Status of External Pins During Idle and Power-down Modes Program Mode 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 17. Program Memory Lock Bits The AT89S52 has three lock bits that can be left unprogrammed (U) or can be programmed (P) to obtain the additional features listed in Table 17-1. Table 17-1. Lock Bit Protection Modes Program Lock Bits LB1 LB2 LB3 Protection Type 1 U U U No program lock features MOVC instructions executed from external program memory are disabled from fetching code bytes from internal memory, EA 2 P U U is sampled and latched on reset, and further programming of the Flash memory is disabled 3 P P U Same as mode 2, but verify is also disabled 4 P P P Same as mode 3, but external execution is also disabled 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. AT89S52 20 1919D–MICRO–6/08

AT89S52 18. Programming the Flash – Parallel Mode The AT89S52 is shipped with the on-chip Flash memory array ready to be programmed. The programming interface needs a high-voltage (12-volt) program enable signal and is compatible with conventional third-party Flash or EPROM programmers. The AT89S52 code memory array is programmed byte-by-byte. Programming Algorithm: Before programming the AT89S52, the address, data, and control signals should be set up according to the “Flash Programming Modes” (Table 22-1) and Figure 22-1 and Figure 22-2. To program the AT89S52, take the following steps: 1. Input the desired memory location on the address lines. 2. Input the appropriate data byte on the data lines. 3. Activate the correct combination of control signals. 4. Raise EA/V to 12V. PP 5. Pulse ALE/PROG once to program a byte in the Flash array or the lock bits. The byte- write cycle is self-timed and typically takes no more than 50 µs. Repeat steps 1 through 5, changing the address and data for the entire array or until the end of the object file is reached. Data Polling: The AT89S52 features Data Polling to indicate the end of a byte write cycle. Dur- ing a write cycle, an attempted read of the last byte written will result in the complement of the written data on P0.7. Once the write cycle has been completed, true data is 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 can also be monitored by the RDY/BSY output signal. P3.0 is pulled low after ALE goes high during programming to indicate BUSY. P3.0 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 data can be read back via the address and data lines for verification. The status of the individ- ual lock bits can be verified directly by reading them back. Reading the Signature Bytes: The signature bytes are read by the same procedure as a nor- mal verification of locations 000H, 100H, and 200H, except that P3.6 and P3.7 must be pulled to a logic low. The values returned are as follows. (000H) = 1EH indicates manufactured by Atmel (100H) = 52H indicates AT89S52 (200H) = 06H Chip Erase: In the parallel programming mode, a chip erase operation is initiated by using the proper combination of control signals and by pulsing ALE/PROG low for a duration of 200 ns - 500 ns. 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 500 ms. During chip erase, a serial read from any address location will return 00H at the data output. 21 1919D–MICRO–6/08

19. Programming the Flash – Serial Mode The Code memory array can be programmed using the serial ISP interface while RST is pulled to V . The serial interface consists of pins SCK, MOSI (input) and MISO (output). After RST is CC set high, the Programming Enable instruction needs to be executed first before other operations can be executed. Before a reprogramming sequence can occur, a Chip Erase operation is required. The Chip Erase operation turns the content of every memory location in the Code array into FFH. Either an external system clock can be 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 1/16 of the crystal frequency. With a 33 MHz oscillator clock, the maximum SCK frequency is 2 MHz. 20. Serial Programming Algorithm To program and verify the AT89S52 in the serial programming mode, the following sequence is recommended: 1. Power-up sequence: a. Apply power between VCC and GND pins. b. Set RST pin to “H”. If a crystal is not connected across pins XTAL1 and XTAL2, apply a 3 MHz to 33 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 16. 3. The Code array is programmed one byte at a time in either the Byte or Page mode. The write cycle is self-timed and typically takes less than 0.5 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 device operation. Power-off sequence (if needed): 1. Set XTAL1 to “L” (if a crystal is not used). 2. Set RST to “L”. 3. Turn V power off. CC Data Polling: The Data Polling feature is also available in the serial mode. In this mode, during a write cycle an attempted read of the last byte written will result in the complement of the MSB of the serial output byte on MISO. 21. Serial Programming Instruction Set The Instruction Set for Serial Programming follows a 4-byte protocol and is shown in Table 24-1. AT89S52 22 1919D–MICRO–6/08

AT89S52 22. Programming Interface – Parallel Mode Every code byte in the Flash array can be programmed 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 major worldwide programming vendors offer support for the Atmel AT89 microcontroller series. Please contact your local programming vendor for the appropriate software revision. Table 22-1. Flash Programming Modes P2.4-0 P1.7-0 ALE/ EA/ P0.7-0 Mode V RST PSEN PROG V P2.6 P2.7 P3.3 P3.6 P3.7 Data Address CC PP (2) Write Code Data 5V H L 12V L H H H H D A12-8 A7-0 IN Read Code Data 5V H L H H L L L H H D A12-8 A7-0 OUT (3) Write Lock Bit 1 5V H L 12V H H H H H X X X (3) Write Lock Bit 2 5V H L 12V H H H L L X X X (3) Write Lock Bit 3 5V H L 12V H L H H L X X X P0.2, Read Lock Bits 5V H L H H H H L H L P0.3, X X 1, 2, 3 P0.4 (1) Chip Erase 5V H L 12V H L H L L X X X Read Atmel ID 5V H L H H L L L L L 1EH X 0000 00H Read Device ID 5V H L H H L L L L L 52H X 0001 00H Read Device ID 5V H L H H L L L L L 06H X 0010 00H Notes: 1. Each PROG pulse is 200 ns - 500 ns for Chip Erase. 2. Each PROG pulse is 200 ns - 500 ns for Write Code Data. 3. Each PROG pulse is 200 ns - 500 ns for Write Lock Bits. 4. RDY/BSY signal is output on P3.0 during programming. 5. X = don’t care. 23 1919D–MICRO–6/08

Figure 22-1. Programming the Flash Memory (Parallel Mode) VCC AT89S52 ADDR. A0-A7 P1.0-P1.7 VCC 0000H/1FFFH PGM P2.0 - P2.4 P0 A8-A12 DATA P2.6 P2.7 SEE FLASH ALE PROG PROGRAMMING P3.3 MODES TABLE P3.6 P3.7 XTAL2 EA V /V IH PP 3-33 MHz RDY/ P3.0 BSY XTAL1 RST V IH GND PSEN Figure 22-2. Verifying the Flash Memory (Parallel Mode) V CC AT89S52 A0-A7 V ADDR. P1.0-P1.7 CC 0000H/1FFFH PGM DATA P2.0 - P2.4 P0 (USE 10K A8-A12 PULLUPS) P2.6 SEE FLASH P2.7 ALE PROGRAMMING P3.3 MODES TABLE P3.6 V P3.7 IH XTAL2 EA 3-33 MHz XTAL1 RST V IH GND PSEN AT89S52 24 1919D–MICRO–6/08

AT89S52 23. Flash Programming and Verification Characteristics (Parallel Mode) T = 20°C to 30°C, V = 4.5 to 5.5V A CC Symbol Parameter Min Max Units V Programming Supply Voltage 11.5 12.5 V PP I Programming Supply Current 10 mA PP I V Supply Current 30 mA CC CC 1/t Oscillator Frequency 3 33 MHz CLCL t Address Setup to PROG Low 48 t AVGL CLCL t Address Hold After PROG 48 t GHAX CLCL t Data Setup to PROG Low 48 t DVGL CLCL t Data Hold After PROG 48 t GHDX CLCL t P2.7 (ENABLE) High to V 48 t EHSH PP CLCL t V Setup to PROG Low 10 µs SHGL PP t V Hold After PROG 10 µs GHSL PP t PROG Width 0.2 1 µs GLGH t Address to Data Valid 48 t AVQV CLCL t ENABLE Low to Data Valid 48 t ELQV CLCL t Data Float After ENABLE 0 48 t EHQZ CLCL t PROG High to BUSY Low 1.0 µs GHBL t Byte Write Cycle Time 50 µs WC Figure 23-1. Flash Programming and Verification Waveforms – Parallel Mode PROGRAMMING VERIFICATION P1.0 - P1.7 ADDRESS ADDRESS P2.0 - P2.4 t AVQV PORT 0 DATA IN DATA OUT t t DVGL GHDX t t AVGL GHAX ALE/PROG t t SHGL t GHSL GLGH V PP LOGIC 1 EA/VPP LOGIC 0 t t EHSH t EHQZ P2.7 ELQV (ENABLE) t GHBL P3.0 (RDY/BSY) BUSY READY t WC 25 1919D–MICRO–6/08

Figure 23-2. Flash Memory Serial Downloading V CC AT89S52 V CC INSTRUCTION P1.5/MOSI INPUT DATA OUTPUT P1.6/MISO CLOCK IN P1.7/SCK XTAL2 3-33 MHz XTAL1 RST V IH GND 24. Flash Programming and Verification Waveforms – Serial Mode Figure 24-1. Serial Programming Waveforms 7 6 5 4 3 2 1 0 AT89S52 26 1919D–MICRO–6/08

AT89S52 Table 24-1. Serial Programming Instruction Set Instruction Format Instruction Byte 1 Byte 2 Byte 3 Byte 4 Operation 1010 1100 0101 0011 xxxx xxxx xxxx xxxx 0110 1001 Enable Serial Programming Programming Enable (Output on while RST is high MISO) 1010 1100 100x xxxx xxxx xxxx xxxx xxxx Chip Erase Flash memory Chip Erase array Read Program Memory 0010 0000 xxx 12 1110A9A8 A7A6A5A4A3A2A1A0 D7D6D5D4 D3D2D1D0 Read data from Program (Byte Mode) A AA memory in the byte mode Write Program Memory 0100 0000 xxx 12 1110A9A8 A7A6A5A4A3A2A1A0 D7D6D5D4 D3D2D1D0 Write data to Program (Byte Mode) A AA memory in the byte mode Write Lock Bits(1) 1010 1100 1110 0012 xxxx xxxx xxxx xxxx Write Lock bits. See Note (1). BB 0010 0100 xxxx xxxx xxxx xxxx xxx 3 2 1 xx Read back current status of B BB Read Lock Bits L LL the lock bits (a programmed lock bit reads back as a “1”) 0010 1000 xxx 2 1098 7 xxx xxx0 Signature Byte Read Signature Bytes A1 A1A1AA A Read Signature Byte 0011 0000 xxx 2 1098 Byte 0 Byte 1... Read data from Program Read Program Memory 1 11AA A AA Byte 255 memory in the Page Mode (Page Mode) (256 bytes) Write Program Memory 0101 0000 xxx12 1110A9A8 Byte 0 Byte 1... Write data to Program A AA Byte 255 memory in the Page Mode (Page Mode) (256 bytes) } Note: 1. B1 = 0, B2 = 0 ---> Mode 1, no lock protection B1 = 0, B2 = 1 ---> Mode 2, lock bit 1 activated Each of the lock bit modes needs to be activated sequentially B1 = 1, B2 = 0 ---> Mode 3, lock bit 2 activated before Mode 4 can be executed. B1 = 1, B2 = 1 ---> Mode 4, lock bit 3 activated After Reset signal is high, SCK should be low for at least 64 system clocks before it goes high to clock in the enable data bytes. No pulsing of Reset signal is necessary. SCK should be no faster than 1/16 of the system clock at XTAL1. For Page Read/Write, the data always starts from byte 0 to 255. After the command byte and upper address byte are latched, each byte thereafter is treated as data until all 256 bytes are shifted in/out. Then the next instruction will be ready to be decoded. 27 1919D–MICRO–6/08

25. Serial Programming Characteristics Figure 25-1. Serial Programming Timing MOSI t t t OVSH SHOX SLSH SCK t SHSL MISO t SLIV Table 25-1. Serial Programming Characteristics, T = -40⋅ C to 85⋅ C, V = 4.0 - 5.5V (Unless Otherwise Noted) A CC Symbol Parameter Min Typ Max Units 1/t Oscillator Frequency 3 33 MHz CLCL t Oscillator Period 30 ns CLCL t SCK Pulse Width High 8 t ns SHSL CLCL t SCK Pulse Width Low 8 t ns SLSH CLCL t MOSI Setup to SCK High t ns OVSH CLCL t MOSI Hold after SCK High 2 t ns SHOX CLCL t SCK Low to MISO Valid 10 16 32 ns SLIV t Chip Erase Instruction Cycle Time 500 ms ERASE t Serial Byte Write Cycle Time 64 t + 400 µs SWC CLCL AT89S52 28 1919D–MICRO–6/08

AT89S52 26. Absolute Maximum Ratings* Operating Temperature..................................-55°C to +125°C *NOTICE: Stresses beyond those listed under “Absolute Maximum Ratings” may cause permanent dam- Storage Temperature.....................................-65°C to +150°C age to the device. This is a stress rating only and functional operation of the device at these or any Voltage on Any Pin other conditions beyond those indicated in the with Respect to Ground.....................................-1.0V to +7.0V operational sections of this specification is not implied. Exposure to absolute maximum rating Maximum Operating Voltage............................................6.6V conditions for extended periods may affect device reliability. DC Output Current......................................................15.0 mA 27. DC Characteristics The values shown in this table are valid for T = -40°C to 85°C and V = 4.0V to 5.5V, unless otherwise noted. A CC Symbol Parameter Condition Min Max Units V Input Low Voltage (Except EA) -0.5 0.2 V -0.1 V IL CC V Input Low Voltage (EA) -0.5 0.2 V -0.3 V IL1 CC V Input High Voltage (Except XTAL1, RST) 0.2 V +0.9 V +0.5 V IH CC CC V Input High Voltage (XTAL1, RST) 0.7 V V +0.5 V IH1 CC CC V Output Low Voltage(1) (Ports 1,2,3) I = 1.6 mA 0.45 V OL OL Output Low Voltage(1) V I = 3.2 mA 0.45 V OL1 (Port 0, ALE, PSEN) OL I = -60 µA, V = 5V ± 10% 2.4 V OH CC Output High Voltage V I = -25 µA 0.75 V V OH (Ports 1,2,3, ALE, PSEN) OH CC I = -10 µA 0.9 V V OH CC I = -800 µA, V = 5V ± 10% 2.4 V OH CC Output High Voltage V I = -300 µA 0.75 V V OH1 (Port 0 in External Bus Mode) OH CC I = -80 µA 0.9 V V OH CC I Logical 0 Input Current (Ports 1,2,3) V = 0.45V -50 µA IL IN Logical 1 to 0 Transition Current I V = 2V, V = 5V ± 10% -300 µA TL (Ports 1,2,3) IN CC I Input Leakage Current (Port 0, EA) 0.45 < V < V ±10 µA LI IN CC RRST Reset Pulldown Resistor 50 300 KΩ C Pin Capacitance Test Freq. = 1 MHz, T = 25°C 10 pF IO A Active Mode, 12 MHz 25 mA Power Supply Current I Idle Mode, 12 MHz 6.5 mA CC Power-down Mode(1) V = 5.5V 50 µA CC Notes: 1. Under steady state (non-transient) conditions, I must be externally limited as follows: OL Maximum I per port pin: 10 mA OL Maximum I per 8-bit port: OL Port 0: 26 mA Ports 1, 2, 3: 15 mA Maximum total I for all output pins: 71 mA OL If I exceeds the test condition, V may exceed the related specification. Pins are not guaranteed to sink current greater OL OL than the listed test conditions. 2. Minimum V for Power-down is 2V. CC 29 1919D–MICRO–6/08

28. AC Characteristics Under operating conditions, load capacitance for Port 0, ALE/PROG, and PSEN = 100 pF; load capacitance for all other outputs = 80 pF. 28.1 External Program and Data Memory Characteristics 12 MHz Oscillator Variable Oscillator Symbol Parameter Min Max Min Max Units 1/t Oscillator Frequency 0 33 MHz CLCL t ALE Pulse Width 127 2t -40 ns LHLL CLCL t Address Valid to ALE Low 43 t -25 ns AVLL CLCL t Address Hold After ALE Low 48 t -25 ns LLAX CLCL t ALE Low to Valid Instruction In 233 4t -65 ns LLIV CLCL t ALE Low to PSEN Low 43 t -25 ns LLPL CLCL t PSEN Pulse Width 205 3t -45 ns PLPH CLCL t PSEN Low to Valid Instruction In 145 3t -60 ns PLIV CLCL t Input Instruction Hold After PSEN 0 0 ns PXIX t Input Instruction Float After PSEN 59 t -25 ns PXIZ CLCL t PSEN to Address Valid 75 t -8 ns PXAV CLCL t Address to Valid Instruction In 312 5t -80 ns AVIV CLCL t PSEN Low to Address Float 10 10 ns PLAZ t RD Pulse Width 400 6t -100 ns RLRH CLCL t WR Pulse Width 400 6t -100 ns WLWH CLCL t RD Low to Valid Data In 252 5t -90 ns RLDV CLCL t Data Hold After RD 0 0 ns RHDX t Data Float After RD 97 2t -28 ns RHDZ CLCL t ALE Low to Valid Data In 517 8t -150 ns LLDV CLCL t Address to Valid Data In 585 9t -165 ns AVDV CLCL t ALE Low to RD or WR Low 200 300 3t -50 3t +50 ns LLWL CLCL CLCL t Address to RD or WR Low 203 4t -75 ns AVWL CLCL t Data Valid to WR Transition 23 t -30 ns QVWX CLCL t Data Valid to WR High 433 7t -130 ns QVWH CLCL t Data Hold After WR 33 t -25 ns WHQX CLCL t RD Low to Address Float 0 0 ns RLAZ t RD or WR High to ALE High 43 123 t -25 t +25 ns WHLH CLCL CLCL AT89S52 30 1919D–MICRO–6/08

AT89S52 29. External Program Memory Read Cycle t LHLL ALE t PLPH t t AVLL t LLIV LLPL PSEN tPLIV t t PXAV PLAZ t t PXIZ LLAX t PXIX PORT0 A0-A7 INSTRIN A0-A7 t AVIV PORT2 A8-A15 A8-A15 30. External Data Memory Read Cycle t LHLL ALE t WHLH PSEN t LLDV t RLRH t LLWL RD t LLAX t t t RLDV RHDZ AVLL t RLAZ t RHDX PORT 0 A0 - A7 FROM RI OR DPL DATA IN A0 - A7 FROM PCL INSTR IN t AVWL t AVDV PORT 2 P2.0 - P2.7 OR A8 - A15 FROM DPH A8 - A15 FROM PCH 31 1919D–MICRO–6/08

31. External Data Memory Write Cycle t LHLL ALE t WHLH PSEN t t LLWL WLWH WR t LLAX t t t AVLL QVWX WHQX t QVWH PORT 0 A0 - A7 FROM RI OR DPL DATA OUT A0 - A7 FROM PCL INSTR IN t AVWL PORT 2 P2.0 - P2.7 OR A8 - A15 FROM DPH A8 - A15 FROM PCH 32. External Clock Drive Waveforms t CHCX tCHCX tCLCH tCHCL V - 0.5V CC 0.7 V CC 0.2 V - 0.1V CC 0.45V t CLCX t CLCL 33. External Clock Drive Symbol Parameter Min Max Units 1/t Oscillator Frequency 0 33 MHz CLCL t Clock Period 30 ns CLCL t High Time 12 ns CHCX t Low Time 12 ns CLCX t Rise Time 5 ns CLCH t Fall Time 5 ns CHCL AT89S52 32 1919D–MICRO–6/08

AT89S52 34. Serial Port Timing: Shift Register Mode Test Conditions The values in this table are valid for V = 4.0V to 5.5V and Load Capacitance = 80 pF. CC 12 MHz Osc Variable Oscillator Symbol Parameter Min Max Min Max Units t Serial Port Clock Cycle Time 1.0 12 t μs XLXL CLCL t Output Data Setup to Clock Rising Edge 700 10 t -133 ns QVXH CLCL t Output Data Hold After Clock Rising Edge 50 2 t -80 ns XHQX CLCL t Input Data Hold After Clock Rising Edge 0 0 ns XHDX t Clock Rising Edge to Input Data Valid 700 10 t -133 ns XHDV CLCL 35. Shift Register Mode Timing Waveforms INSTRUCTION 0 1 2 3 4 5 6 7 8 ALE t XLXL CLOCK t QVXH t XHQX WRITETOSBUF 0 1 2 3 4 5 6 7 t OUTPUTDATA tXHDV XHDX SETTI CLEARRI VALID VALID VALID VALID VALID VALID VALID VALID INPUTDATA SETRI 36. AC Testing Input/Output Waveforms(1) V - 0.5V CC 0.2 V + 0.9V CC TEST POINTS 0.2 V - 0.1V 0.45V CC Note: 1. AC Inputs during testing are driven at V - 0.5V CC for a logic 1 and 0.45V for a logic 0. Timing measurements are made at V min. for a logic 1 and V max. for a logic 0. IH IL 37. Float Waveforms(1) V + 0.1V V - 0.1V LOAD OL V Timing Reference LOAD Points V - 0.1V V + 0.1V LOAD OL 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 V /V level occurs. OH OL 33 1919D–MICRO–6/08

38. Ordering Information 38.1 Green Package Option (Pb/Halide-free) Speed Power (MHz) Supply Ordering Code Package Operation Range AT89S52-24AU 44A Industrial 24 4.0V to 5.5V AT89S52-24JU 44J (-40°C to 85°C) AT89S52-24PU 40P6 AT89S52-33AU 44A Industrial 33 4.5V to 5.5V AT89S52-33JU 44J (-40°C to 85°C) AT89S52-33PU 40P6 Package Type 44A 44-lead, Thin Plastic Gull Wing Quad Flatpack (TQFP) 44J 44-lead, Plastic J-leaded Chip Carrier (PLCC) 40P6 40-pin, 0.600" Wide, Plastic Dual Inline Package (PDIP) AT89S52 34 1919D–MICRO–6/08

AT89S52 39. Packaging Information 39.1 44A – TQFP PIN 1 B PIN 1 IDENTIFIER e E1 E D1 D C 0˚~7˚ A1 A2 A L COMMON DIMENSIONS (Unit of Measure = mm) SYMBOL MIN NOM MAX NOTE 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 Note 2 E 11.75 12.00 12.25 Notes: 1.This package conforms to JEDEC reference MS-026, Variation ACB. E1 9.90 10.00 10.10 Note 2 2.Dimensions D1 and E1 do not include mold protrusion. Allowable protrusion is 0.25 mm per side. Dimensions D1 and E1 are maximum B 0.30 – 0.45 plastic body size dimensions including mold mismatch. C 0.09 – 0.20 3. Lead coplanarity is 0.10 mm maximum. L 0.45 – 0.75 e 0.80 TYP 10/5/2001 TITLE DRAWING NO. REV. 2325 Orchard Parkway 44A, 44-lead, 10 x 10 mm Body Size, 1.0 mm Body Thickness, San Jose, CA 95131 44A B R 0.8 mm Lead Pitch, Thin Profile Plastic Quad Flat Package (TQFP) 35 1919D–MICRO–6/08

39.2 44J – PLCC 1.14(0.045) X 45˚ 1.14(0.045) X 45˚ PIN NO. 1 0.318(0.0125) IDENTIFIER 0.191(0.0075) E1 E B1 D2/E2 B e A2 D1 A1 D A 0.51(0.020)MAX 45˚ MAX (3X) COMMON DIMENSIONS (Unit of Measure = mm) SYMBOL MIN NOM MAX NOTE A 4.191 – 4.572 A1 2.286 – 3.048 A2 0.508 – – D 17.399 – 17.653 D1 16.510 – 16.662 Note 2 E 17.399 – 17.653 Notes: 1.This package conforms to JEDEC reference MS-018, Variation AC. E1 16.510 – 16.662 Note 2 2.Dimensions D1 and E1 do not include mold protrusion. Allowable protrusion is .010"(0.254 mm) per side. Dimension D1 D2/E2 14.986 – 16.002 and E1 include mold mismatch and are measured at the extreme B 0.660 – 0.813 material condition at the upper or lower parting line. 3. Lead coplanarity is 0.004" (0.102 mm) maximum. B1 0.330 – 0.533 e 1.270 TYP 10/04/01 TITLE DRAWING NO. REV. 2325 Orchard Parkway 44J, 44-lead, Plastic J-leaded Chip Carrier (PLCC) San Jose, CA 95131 44J B R AT89S52 36 1919D–MICRO–6/08

AT89S52 39.3 40P6 – PDIP D PIN 1 E1 A SEATING PLANE A1 L B B1 e E COMMON DIMENSIONS 0º ~ 15º REF (Unit of Measure = mm) C SYMBOL MIN NOM MAX NOTE eB A – – 4.826 A1 0.381 – – D 52.070 – 52.578 Note 2 E 15.240 – 15.875 E1 13.462 – 13.970 Note 2 B 0.356 – 0.559 B1 1.041 – 1.651 Notes: 1.This package conforms to JEDEC reference MS-011, Variation AC. 2.Dimensions D and E1 do not include mold Flash or Protrusion. L 3.048 – 3.556 Mold Flash or Protrusion shall not exceed 0.25 mm (0.010"). C 0.203 – 0.381 eB 15.494 – 17.526 e 2.540 TYP 09/28/01 TITLE DRAWING NO. REV. 2325 Orchard Parkway 40P6, 40-lead (0.600"/15.24 mm Wide) Plastic Dual R San Jose, CA 95131 Inline Package (PDIP) 40P6 B 37 1919D–MICRO–6/08

Headquarters International Atmel Corporation Atmel Asia Atmel Europe Atmel Japan 2325 Orchard Parkway Room 1219 Le Krebs 9F, Tonetsu Shinkawa Bldg. San Jose, CA 95131 Chinachem Golden Plaza 8, Rue Jean-Pierre Timbaud 1-24-8 Shinkawa USA 77 Mody Road Tsimshatsui BP 309 Chuo-ku, Tokyo 104-0033 Tel: 1(408) 441-0311 East Kowloon 78054 Saint-Quentin-en- Japan Fax: 1(408) 487-2600 Hong Kong Yvelines Cedex Tel: (81) 3-3523-3551 Tel: (852) 2721-9778 France Fax: (81) 3-3523-7581 Fax: (852) 2722-1369 Tel: (33) 1-30-60-70-00 Fax: (33) 1-30-60-71-11 Product Contact Web Site Technical Support Sales Contact www.atmel.com mcu@atmel.com www.atmel.com/contacts Literature Requests www.atmel.com/literature Disclaimer: The information in this document is provided in connection with Atmel products. No license, express or implied, by estoppel or otherwise, to any intellectual property right is granted by this document or in connection with the sale of Atmel products. EXCEPT AS SET FORTH IN ATMEL’S TERMS AND CONDI- TIONS OF SALE LOCATED ON ATMEL’S WEB SITE, ATMEL ASSUMES NO LIABILITY WHATSOEVER AND DISCLAIMS ANY EXPRESS, IMPLIED OR STATUTORY WARRANTY RELATING TO ITS PRODUCTS INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTY OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE, OR NON-INFRINGEMENT. IN NO EVENT SHALL ATMEL BE LIABLE FOR ANY DIRECT, INDIRECT, CONSEQUENTIAL, PUNITIVE, SPECIAL OR INCIDEN- TAL DAMAGES (INCLUDING, WITHOUT LIMITATION, DAMAGES FOR LOSS OF PROFITS, BUSINESS INTERRUPTION, OR LOSS OF INFORMATION) ARISING OUT OF THE USE OR INABILITY TO USE THIS DOCUMENT, EVEN IF ATMEL HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGES. Atmel makes no representations or warranties with respect to the accuracy or completeness of the contents of this document and reserves the right to make changes to specifications and product descriptions at any time without notice. Atmel does not make any commitment to update the information contained herein. Unless specifically provided otherwise, Atmel products are not suitable for, and shall not be used in, automotive applications. Atmel’s products are not intended, authorized, or warranted for use as components in applications intended to support or sustain life. © 2008 Atmel Corporation. All rights reserved. Atmel®, logo and combinations thereof, and others are registered trademarks or trademarks of Atmel Corporation or its subsidiaries. Other terms and product names may be trademarks of others. 1919D–MICRO–6/08

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