Features • Compatible with MCS-51™ Products • 12K Bytes of In-System Reprogrammable Downloadable Flash Memory • • • • • • • • • • • • • • – SPI Serial Interface for Program Downloading – Endurance: 1,000 Write/Erase Cycles 4.0V 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 Description The AT89S53 is a low-power, high-performance CMOS 8-bit microcomputer with 12K bytes of Downloadable Flash programmable and erasable read only memory. 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 onchip 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 AT89S53 is a powerful microcomputer which provides a highly flexible and cost effective solution to many embedded control applications. The AT89S53 provides the following standard features: 12K bytes of Downloadable Flash, 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 AT89S53 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 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 Bit 2 has been activated. 8-Bit Microcontroller with 12K Bytes Flash AT89S53 0787B-B–12/97 4-217 Pin Configurations PDIP 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) 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) (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 40 39 38 37 36 35 34 33 32 31 30 29 28 27 26 25 24 23 22 21 7 8 9 10 11 12 13 14 15 16 17 39 38 37 36 35 34 33 32 31 30 29 18 19 20 21 22 23 24 25 26 27 28 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 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 (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 PLCC 44 43 42 41 40 39 38 37 36 35 34 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) TQFP 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) (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 12 13 14 15 16 17 18 19 20 21 22 (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 Pin Description Port 0 also receives the code bytes during Flash programming and outputs the code bytes during program verification. External pullups are required during program verification. VCC Supply voltage. GND Ground. 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 highimpedance inputs. Port 0 can also be configured to be the multiplexed loworder address/data bus during accesses to external program and data memory. In this mode, P0 has internal pullups. 4-218 AT89S53 Port 1 Port 1 is an 8-bit bidirectional I/O port with internal pullups. 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 pullups 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 pullups. 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. AT89S53 Block Diagram P0.0 - P0.7 P2.0 - P2.7 PORT 0 DRIVERS PORT 2 DRIVERS VCC GND 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 INSTRUCTION REGISTER DPTR 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 4-219 Pin Description 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 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) P1.1 T2EX (Timer/Counter 2 capture/reload trigger and direction control) P3.4 T0 (timer 0 external input) P3.5 T1 (timer 1 external input) P1.4 SS (Slave port select input) P3.6 WR (external data memory write strobe) P1.5 MOSI (Master data output, slave data input pin for SPI channel) P3.7 RD (external data memory read strobe) 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 bidirectional I/O port with internal pullups. 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 pullups 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 pullups. 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 pullups 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 bidirectional I/O port with internal pullups. 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 pullups and can be used as inputs. As inputs, Port 3 pins that are externally being pulled low will source current (IIL) because of the pullups. Port 3 also serves the functions of various special features of the AT89S53, as shown in the following table. Port 3 also receives some control signals for Flash programming and verification. 4-220 AT89S53 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 AT89S53 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 12volt programming is selected. AT89S53 XTAL1 Input to the inverting oscillator amplifier and input to the internal clock operating circuit. XTAL2 Output from the inverting oscillator amplifier. 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. Table 1. AT89S53 SFR Map and Reset Values 0F8H 0F0H 0FFH B 00000000 0F7H 0E8H 0E0H 0EFH ACC 00000000 0E7H 0D8H 0DFH 0D0H PSW 00000000 0C8H T2CON 00000000 T2MOD XXXXXX00 RCAP2L 00000000 RCAP2H 00000000 TL2 00000000 SPCR 000001XX 0D7H TH2 00000000 0CFH 0C0H 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 WCON 00000010 97H 8FH SPDR XXXXXXXX PCON 0XXX0000 87H 4-221 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. Watchdog Control Register The WCON register contains control bits for the Watchdog Timer (shown in Table 3). The DPS bit selects one of two DPTR registers available. 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. 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. 4-222 AT89S53 AT89S53 Dual Data Pointer Registers To facilitate accessing 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 WCON selects DP0 and DPS = 1 selects DP1. The user should always initalize 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 3. WCON—Watchdog Control Register WCON Address = 96H Bit Reset Value = 0000 0010B PS2 PS1 PS0 reserved reserved 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. 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 Watchdog Timer Reset. 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. WDTEN Watchdog Timer Enable Bit. WDTEN = 1 enables the watchdog timer and WDTEN = 0 disables the watchdog timer. 4-223 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: SPR1SPR0SCK = FOSC. divided by 0 0 4 0 1 16 1 0 64 1 1 128 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 accessing 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. 4-224 AT89S53 AT89S53 Table 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 - RAM Programmable Watchdog Timer The AT89S53 implements 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). The programmable Watchdog Timer (WDT) operates from an independent oscillator. The prescaler bits, PS0, PS1 and PS2 in SFR WCON 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 WCON (address = 96H). The WDT is reset by setting the WDTRST bit in WCON. 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 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. WDT Prescaler Bits Period (nominal) PS2 PS1 PS0 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 4-225 Timer 0 and 1 Timer 0 and Timer 1 in the AT89S53 operate the same way as Timer 0 and Timer 1 in the AT89C51, AT89C52 and AT89C55. For further information, see the October 1995 Microcontroller Data Book, page 2-45, section titled, “Timer/Counters.” Table 8. Timer 2 Operating Modes RCLK + TCLK CP/RL2 TR2 0 0 1 16-bit Auto-Reload 0 1 1 16-bit Capture 1 X 1 Baud Rate Generator X X 0 (Off) 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. 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. MODE 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 lto-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. 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 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 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 4-226 AT89S53 AT89S53 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) 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. 4-227 Figure 3. Timer 2 Auto Reload Mode (DCEN = 1) 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 CONTROL EXEN2 4-228 AT89S53 TIMER 2 INTERRUPT Tx CLOCK AT89S53 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. 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 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. 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. Figure 5. Timer 2 in Clock-Out Mode 4-229 Programmable Clock Out UART 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 at 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. The UART in the AT89S53 operates the same way as the UART in the AT89C51, AT89C52 and AT89C55. For further information, see the October 1995 Microcontroller Data Book, page 2-49, section titled, “Serial Interface.” Serial Peripheral Interface The serial peripheral interface (SPI) allows high-speed synchronous data transfer between the AT89S53 and peripheral devices or between several AT89S53 devices. The AT89S53 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 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. Figure 6. SPI Block Diagram S LSB S 8/16-BIT SHIFT REGISTER READ DATA BUFFER DIVIDER ÷4÷16÷64÷128 CLOCK SPI CLOCK (MASTER) MOSI P1.5 SCK 1.7 M SPR0 SPI STATUS REGISTER SPR0 SPR1 CPHA CPOL MSTR SPI CONTROL REGISTER 8 8 SPI INTERRUPT INTERNAL REQUEST DATA BUS AT89S53 DORD SPE 8 SPIE MSTR SPE WCOL SPI CONTROL DORD SPE SS P1.4 MSTR SPR1 S CLOCK LOGIC SELECT SPIF PIN CONTROL LOGIC MSB 4-230 MISO P1.6 M M OSCILLATOR AT89S53 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 Figures 8 and 9. 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, 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 Figure 8. SPI transfer Format with CPHA = 0 *Not defined but normally MSB of character just received 4-231 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) *Not defined but normally LSB of previously transmitted character Interrupts The AT89S53 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 unimple- mented. 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. Table 10. Interrupt Enable (IE) Register Figure 10. Interrupt Sources (MSB) EA (LSB) — 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. 4-232 AT89S53 AT89S53 Figure 12. External Clock Drive Configuration Figure 11. Oscillator Connections Note: C1, C2 = 30 pF ± 10 pF for Crystals = 40 pF ± 10 pF for Ceramic Resonators Oscillator Characteristics 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. 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. 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 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. Idle Mode In idle mode, the CPU puts itself to sleep while all the onchip 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 Status of External Pins During Idle and Power Down Modes 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 4-233 Program Memory Lock Bits The AT89S53 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 Protection Type 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. 4 P P P Same as Mode 3, but external execution is also disabled. Notes: 1. U = Unprogrammed 2. P = Programmed Programming the Flash Parallel Programming Algorithm Atmel’s AT89S53 Flash Microcontroller offers 12K bytes of in-system reprogrammable Flash Code memory. The AT89S53 is normally shipped with the on-chip Flash Code memory array in the erased state (i.e. contents = FFH) and ready to be programmed. This device supports a High-Voltage (12V) Parallel programming mode and a LowVoltage (5V) Serial programming mode. The serial programming mode provides a convenient way to download the AT89S53 inside the user’s system. The parallel programming mode is compatible with conventional third party Flash or EPROM programmers. The Code memory array occupies one contiguous address space from 0000H to 2FFFH. The Code array on the AT89S53 is programmed byte-bybyte 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 non-blank byte, the user needs to use the Chip Erase operation first to erase the entire Code memory array. To program and verify the AT89S53 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, 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. 4-234 AT89S53 AT89S53 8. Repeat steps 3 through 7 changing the address and data for the entire 12K-byte 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. The AT89S53 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) = 53H indicates 89S53 DATA Polling The AT89S53 features DATA Polling to indicate the end of a write cycle. During a 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 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 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 array is 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. Programming Interface Every code byte in the Flash array can be written, and the entire array can be erased, by using the appropriate combination of control signals. The write operation cycle is selftimed and once initiated, will automatically time itself to completion. All major programming vendors offer worldwide support for the Atmel microcontroller series. Please contact your local programming vendor for the appropriate software revision. Serial Downloading The Code memory array 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 the Code array into FFH. The Code memory array has an address space of 0000H to 2FFFH. 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 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. 4-235 Serial Programming Algorithm To program and verify the AT89S53 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 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 self-timed 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. Power-off sequence (if needed): Set XTAL1 to “L” (if a crystal is not used). Set RST to “L”. Turn VCC power off. Serial Programming Instruction The Instruction Set for Serial Programming follows a 3-byte protocol and is shown in the following table: Instruction Set Instruction Input Format Operation 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 the 12K memory array. xxxx xxxx Read data from Code memory array at the selected address. The 6 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. data in Write data to Code memory location at selected address. The address bits are the 6 MSBs of the first byte together with the second byte. low addr Write Code Memory low addr 01 Write Lock Bits Notes: 10 1010 1100 LB1 LB2 LB3 Read Code Memory A12 A11 A10 A9 A8 A13 Byte 2 A12 A11 A10 A9 A8 A13 Byte 1 x x111 Write lock bits. Set LB1, LB2 or LB3 = “0” to program lock bits. 1. DATA polling is used to indicate the end of a write cycle which typically takes less than 2.5 ms at 5V. 2. “x” = don’t care. 4-236 xxxx xxxx AT89S53 AT89S53 Flash 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 Serial Prog. Modes RST PSEN ALE/PROG EA/VPP H h (1) h (1) x Chip Erase H L Write (12K bytes) Memory H L Read (12K bytes) Memory H L Write Lock Bits: H L Read Lock Bits: H L (2) H H Read Atmel Code H L H Read Device Code H L H Serial Prog. Enable H H L Read Serial Prog. Fuse H L Notes: (2) L Serial Prog. Disable 12V (2) H H H L L 12V L L L L DOUT 30H 12V L L L L DOUT 31H 12V L H L H P0.0 = 0 X 12V L H L H P0.0 = 1 X 12V H H L H @P0.0 X 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 4-237 Figure 14. Flash Serial Downloading Figure 13. Programming the Flash Memory +5V +4.0V to 6.0V AT89S53 A0 - A7 ADDR. 0000H/2FFFH AT89S53 VCC P1 VCC PGM DATA P0 P2.0 - P2.5 A8 - A13 P2.6 SEE FLASH PROGRAMMING MODES TABLE PROG ALE P2.7 P3.6 INSTRUCTION INPUT P1.5/MOSI DATA OUTPUT P1.6/MISO CLOCK IN P1.7/SCK P3.7 XTAL2 VPP EA 3-24 Mhz 3-24 Mhz XTAL1 GND VI H RST PSEN +5V AT89S53 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 XTAL1 GND Figure 15. Verifying the Flash Memory 4-238 XTAL2 PSEN AT89S53 RST VI H AT89S53 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 4-239 Flash Programming and Verification Waveforms - Parallel Mode 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 4-240 AT89S53 AT89S53 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 = 4.0V to 6.0V, 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 (Except XTAL1, RST) 0.2 VCC + 0.9 VCC + 0.5 V VIH1 Input High Voltage (XTAL1, RST) 0.7 VCC VCC + 0.5 V VOL Output Low Voltage (1) (Ports 1,2,3) 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% 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% VOH1 Output High Voltage (Port 0 in External Bus Mode) 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 Pulldown Resistor 300 KΩ CIO Pin Capacitance Test Freq. = 1 MHz, TA = 25°C 10 pF Active Mode, 12 MHz 25 mA Idle Mode, 12 MHz 6.5 mA VCC = 6V 100 µA VCC = 3V 40 µA 50 Power Supply Current ICC Power Down Mode (2) Notes: 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. 4-241 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 12MHz Oscillator Symbol Parameter 1/tCLCL Oscillator Frequency tLHLL ALE Pulse Width 127 2tCLCL - 40 ns tAVLL Address Valid to ALE Low 43 tCLCL - 13 ns tLLAX Address Hold After ALE Low 48 tCLCL - 20 ns tLLIV ALE Low to Valid Instruction In tLLPL ALE Low to PSEN Low 43 tCLCL - 13 ns tPLPH PSEN Pulse Width 205 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 312 5tCLCL - 55 ns tPLAZ PSEN Low to Address Float 10 10 ns tRLRH RD Pulse Width 400 6tCLCL - 100 ns tWLWH WR Pulse Width 400 6tCLCL - 100 ns tRLDV RD Low to Valid Data In tRHDX Data Hold After RD tRHDZ Data Float After RD 97 2tCLCL - 28 ns tLLDV ALE Low to Valid Data In 517 8tCLCL - 150 ns tAVDV Address to Valid Data In 585 9tCLCL - 165 ns tLLWL ALE Low to RD or WR Low 200 3tCLCL + 50 ns tAVWL Address to RD or WR Low 203 4tCLCL - 75 ns tQVWX Data Valid to WR Transition 23 tCLCL - 20 ns tQVWH Data Valid to WR High 433 7tCLCL - 120 ns tWHQX Data Hold After WR 33 tCLCL - 20 ns tRLAZ RD Low to Address Float tWHLH RD or WR High to ALE High 4-242 Min AT89S53 Max Variable Oscillator Min Max Units 0 24 MHz 233 4tCLCL - 65 145 0 3tCLCL - 45 0 59 75 tCLCL - 8 0 5tCLCL - 90 3tCLCL - 50 0 43 123 tCLCL - 20 ns ns 0 300 ns ns tCLCL - 10 252 ns ns ns 0 ns tCLCL + 25 ns AT89S53 External Program Memory Read Cycle External Data Memory Read Cycle 4-243 External Data Memory Write Cycle External Clock Drive Waveforms External Clock Drive Symbol Parameter VCC = 4.0V to 6.0V 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 4-244 AT89S53 AT89S53 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. Symbol Parameter 12 MHz Oscillator Min Max Variable Oscillator Min Units Max tXLXL Serial Port Clock Cycle Time 1.0 12tCLCL µs tQVXH Output Data Setup to Clock Rising Edge 700 10tCLCL - 133 ns tXHQX Output Data Hold After Clock Rising Edge 50 2tCLCL - 117 ns tXHDX Input Data Hold After Clock Rising Edge 0 0 ns tXHDV Clock Rising Edge to Input Data Valid 700 10tCLCL - 133 ns Shift Register Mode Timing Waveforms AC Testing Input/Output Waveforms (1) Float Waveforms (1) Notes: Notes: 1. AC Inputs during testing are driven at V CC - 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. 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. 4-245 Notes: 4-246 1. XTAL1 tied to GND for ICC (power down) 2. Lock bits programmed AT89S53 AT89S53 Ordering Information Speed (MHz) Power Supply Ordering Code Package 16 4.0V to 6.0V AT89S53-16AA AT89S53-16JA AT89S53-16PA 44A 44J 40P6 Automotive (-40°C to 105°C) 24 4.0V to 6.0V AT89S53-24AC AT89S53-24JC AT89S53-24PC 44A 44J 40P6 Commercial (0°C to 70°C) 4.0V to 6.0V AT89S53-24AI AT89S53-24JI AT89S53-24PI 44A 44J 40P6 Industrial (-40°C to 85°C) 4.5V to 5.5V AT89S53-33AC AT89S53-33JC AT89S53-33PC 44A 44J 40P6 Commercial (0°C to 70°C) 33 Operation Range = Preliminary Information 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) 4-247 4-248 AT89S53