IS89C52-40W

IS89C52 IS89C52 CMOS SINGLE CHIP 8-BIT MICROCONTROLLER with 8-Kbytes of FLASH ISSI NOVEMBER 1998 GENERAL DESCRIPTION ISSI® ® FEATURES • 80C51 based architecture • 8-Kbytes of on-chip Reprogrammable Flash Memory • 256 x 8 RAM • Three 16-bit Timer/Counters • Full duplex serial channel • Boolean processor • Four 8-bit I/O ports, 32 I/O lines • Memory addressing capability – 64K ROM and 64K RAM • Program memory lock – Lock bits (3) • Power save modes: – Idle and power-down • Eight interrupt sources • Most instructions execute in 0.3 µs • CMOS and TTL compatible • Maximum speed: 40 MHz @ Vcc = 5V • Industrial temperature available • Packages available: – 40-pin DIP – 44-pin PLCC – 44-pin PQFP The ISSI IS89C52 is a high-performance microcontroller fabricated using high-density CMOS technology. The CMOS IS89C52 is functionally compatible with the industry standard 80C51 microcontrollers. The IS89C52 is designed with 8-Kbytes of Flash memory, 258 x 8 RAM; 32 programmable I/O lines; a serial I/O port for either multiprocessor communications, I/O expansion or full duplex UART; three 16-bit timer/counters; an eight-source, two-priority-level, nested interrupt structure; and an on-chip oscillator and clock circuit. The IS89C52 can be expanded using standard TTL compatible memory. T2/P1.0 T2EX/P1.1 P1.2 P1.3 P1.4 P1.5 P1.6 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 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 40 39 38 37 36 35 34 33 32 31 30 29 28 27 26 25 24 23 22 21 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 Figure 1. IS89C52 Pin Configuration: 40-pin PDIP ISSI reserves the right to make changes to its products at any time without notice in order to improve design and supply the best possible product. We assume no responsibility for any errors which may appear in this publication. © Copyright 1998, Integrated Silicon Solution, Inc. Integrated Silicon Solution, Inc. — 1-800-379-4774 MC013-1C 11/21/98 1 IS89C52 ISSI P1.1/T2EX P0.0/AD0 P0.1/AD1 P0.2/AD2 P0.3/AD3 ® P1.0/T2 INDEX P1.5 P1.6 P1.7 RST RxD/P3.0 NC TxD/P3.1 INT0/P3.2 INT1/P3.3 T0/P3.4 T1/P3.5 7 8 9 10 11 12 13 14 15 16 17 6 5 4 3 2 1 44 VCC P1.4 P1.3 P1.2 NC 43 42 41 40 39 38 37 36 35 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 TOP VIEW 34 33 32 31 30 29 18 19 20 21 22 23 24 25 26 27 28 A8/P2.0 A9/P2.1 A10/P2.2 A11/P2.3 Figure 2. IS89C52 Pin Configuration: 44-pin PLCC 2 Integrated Silicon Solution, Inc. — 1-800-379-4774 MC013-1C 11/21/98 A12/P2.4 WR/P3.6 RD/P3.7 XTAL2 XTAL1 GND NC IS89C52 ISSI P1.1/T2EX P0.0/AD0 P0.1/AD1 P0.2/AD2 P0.3/AD3 ® P1.0/T2 P1.4 P1.3 P1.2 44 P1.5 P1.6 P1.7 RST RxD/P3.0 NC TxD/P3.1 INT0/P3.2 INT1/P3.3 T0/P3.4 T1/P3.5 1 2 3 4 5 6 7 8 9 10 11 12 43 42 41 40 39 VCC 38 NC 37 36 35 34 33 32 31 30 29 29 27 26 25 24 23 P0.4/AD4 P0.5/AD5 P0.6/AD6 P0.7/AD7 EA NC ALE PSEN P2.7/A15 P2.6/A14 P2.5/A13 13 14 15 16 17 18 19 20 21 22 A10/P2.2 A11/P2.3 Figure 3. IS89C52 Pin Configuration: 44-pin PQFP Integrated Silicon Solution, Inc. — 1-800-379-4774 MC013-1C 11/21/98 A12/P2.4 WR/P3.6 RD/P3.7 XTAL2 XTAL1 A8/P2.0 A9/P2.1 GND NC 3 IS89C52 ISSI P2.0-P2.7 P0.0-P0.7 ® Vcc P2 DRIVERS P0 DRIVERS GND ADDRESS DECODER & 256 BYTES RAM ADDRESS DECODER & 8K FLASH 3 LOCK BITS & 32 BYTES ENCRYPTION RAM ADDR REGISTER P2 LATCH P0 LATCH B REGISTER STACK POINT ACC PROGRAM ADDRESS REGISTER PCON SCON T2CON TH0 TL1 TH2 RCAP2L SBUF TMOD TCON TL0 TH1 TL2 RCAP2H IE IP TMP2 TMP1 PROGRAM COUNTER INTERRUPT BLOCK SERIAL PORT BLOCK TIMER BLOCK ALU PC INCREMENTER PSW BUFFER PSEN ALE/PROG RST EA/VPP TIMING AND CONTROL INSTRUCTION REGISTER DPTR P3 LATCH OSCILLATOR XTAL1 XTAL2 P3 DRIVERS P1 LATCH P1 DRIVERS P3.0-P3.7 P1.0-P1.7 Figure 4. IS89C52 Block Diagram 4 Integrated Silicon Solution, Inc. — 1-800-379-4774 MC013-1C 11/21/98 IS89C52 Table 1. Detailed Pin Description Symbol ALE/PROG PDIP 30 PLCC 33 PQFP 27 I/O I/O Name and Function ISSI ® EA/VPP Address Latch Enable: Output pulse for latching the low byte of the address during an address to the external memory. In normal operation, ALE is emitted at a constant rate of 1/6 the oscillator frequency, and can be used for external timing or clocking. Note that one ALE pulse is skipped during each access to external data memory. This pin is also the Program Pulse input (PROG) during Flash programming. 31 35 29 I External Access enable: EA must be externally held low to enable the device to fetch code from external program memory locations 0000H to FFFFH. If EA is held high, the device executes from internal program memory unless the program counter contains an address greater than 0FFFH. This also receives the 12V programming enable voltage (VPP) during Flash programming. Port 0: Port 0 is an 8-bit open-drain, bidirectional I/O port. Port 0 pins that have 1s written to them float and can be used as highimpedance inputs. Port 0 is also the multiplexed low-order address and data bus during accesses to external program and data memory. In this application, it uses strong internal pullups when emitting 1s. Port 0 also receives the code bytes during programmable memory programming and outputs the code bytes during program verification. External pullups are required during program verification. Port 1: Port 1 is an 8-bit bidirectional I/O port with internal pullups. Port 1 pins that have 1s written to them are pulled high by the internal pullups and can be used as inputs. As inputs, Port 1 pins that are externally pulled low will source current because of the internal pullups. (See DC Characteristics: IIL). The Port 1 output buffers can sink/source four TTL inputs. Port 1 also receives the low-order address byte during Flash programming and verification. P0.0-P0.7 39-32 43-36 37-30 I/O P1.0-P1.7 1-8 2-9 40-44 1-3 I/O 1 2 P2.0-P2.7 21-28 2 3 24-31 40 41 18-25 I I I/O T2(P1.0): Timer/Counter 2 external count input. T2EX(P1.1): Timer/Counter 2 trigger input. Port 2: Port 2 is an 8-bit bidirectional I/O port with internal pullups. Port 2 pins that have 1s written to them are pulled high by the internal pullups and can be used as inputs. As inputs, Port 2 pins that are externally pulled low will source current because of the internal pullups. (See DC Characteristics: IIL). Port 2 emits the high order address byte during fetches from external program memory and during accesses to external data memory that used 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 [i = 0, 1]), Port 2 emits the contents of the P2 Special Function Register. Port 2 also receives the high-order bits and some control signals during Flash programming and verification. P2.6 and P2.7 are the control signals while the chip programs and erases. Integrated Silicon Solution, Inc. — 1-800-379-4774 MC013-1C 11/21/98 5 IS89C52 Table 1. Detailed Pin Description (continued) Symbol P3.0-P3.7 PDIP 10-17 PLCC 11, 13-19 PQFP 5, 7-13 I/O I/O Name and Function ISSI ® Port 3: Port 3 is an 8-bit bidirectional I/O port with internal pullups. Port 3 pins that have 1s written to them are pulled high by the internal pullups and can be used as inputs. As inputs, Port 3 pins that are externally pulled low will source current because of the internal pullups. (See DC Characteristics: IIL). Port 3 also serves the special features of the IS89C52, as listed below: 10 11 12 13 14 15 16 17 11 13 14 15 16 17 18 19 32 5 7 8 9 10 11 12 13 26 I O I I I I O O O RxD (P3.0): Serial input port. TxD (P3.1): Serial output port. INT0 (P3.2): External interrupt 0. INT1 (P3.3): External interrupt 1. T0 (P3.4): Timer 0 external input. T1 (P3.5): Timer 1 external input. WR (P3.6): External data memory write strobe. RD (P3.7): External data memory read strobe. Program Store Enable: The read strobe to external program memory. When the device is executing code from the external program memory, PSEN is activated twice each machine cycle except that two PSEN activations are skipped during each access to external data memory. PSEN is not activated during fetches from internal program memory. Reset: A high on this pin for two machine cycles while the oscillator is running, resets the device. An internal MOS resistor to GND permits a power-on reset using only an external capacitor connected to Vcc. Crystal 1: Input to the inverting oscillator amplifier and input to the internal clock generator circuits. Crystal 2: Output from the inverting oscillator amplifier. Ground: 0V reference. Power Supply: This is the power supply voltage for operation. PSEN 29 RST 9 10 4 I XTAL 1 XTAL 2 GND Vcc 19 18 20 40 21 20 22 44 15 14 16 38 I O I I 6 Integrated Silicon Solution, Inc. — 1-800-379-4774 MC013-1C 11/21/98 IS89C52 ISSI ® OPERATING DESCRIPTION The detail description of the IS89C52 included in this description are: • Memory Map and Registers • Timer/Counters • Serial Interface • Interrupt System • Other Information • Flash Memory addressing. Figure 6 shows internal data memory organization and SFR Memory Map. The lower 128 bytes of RAM can be divided into three segments as listed below and shown in Figure 7. 1. Register Banks 0-3: locations 00H through 1FH (32 bytes). The device after reset defaults to register bank 0. To use the other register banks, the user must select them in software. Each register bank contains eight 1-byte registers R0-R7. Reset initializes the stack point to location 07H, and is incremented once to start from 08H, which is the first register of the second register bank. 2. Bit Addressable Area: 16 bytes have been assigned for this segment 20H-2FH. Each one of the 128 bits of this segment can be directly addressed (0-7FH). Each of the 16 bytes in this segment can also be addressed as a byte. 3. Scratch Pad Area: 30H-7FH are available to the user as data RAM. However, if the data pointer has been initialized to this area, enough bytes should be left aside to prevent SP data destruction. MEMORY MAP AND REGISTERS Memory The IS89C52 has separate address spaces for program and data memory. The program and data memory can be up to 64K bytes long. The lower 8K program memory can reside on-chip. Figure 5 shows a map of the IS89C52 program and data memory. The IS89C52 has 256 bytes of on-chip RAM, plus numbers of special function registers. The lower 128 bytes can be accessed either by direct addressing or by indirect Program Memory (Read Only) FFFFH: 64K Data Memory (Read/Write) FFFFH: External 1FFFH: 8K EA = 0 External 0000 EA = 1 Internal Internal FFH: 00 0000 PSEN RD WR Figure 5. IS89C52 Program and Data Memory Structure Integrated Silicon Solution, Inc. — 1-800-379-4774 MC013-1C 11/21/98 7 IS89C52 SPECIAL FUNCTION REGISTERS The Special Function Registers (SFR's) are located in upper 128 Bytes direct addressing area. The SFR Memory Map in Figure 6 shows that. Not all of the addresses are occupied. Unoccupied addresses are not implemented on the chip. Read accesses to these addresses in general return random data, and write accesses have no effect. User software should not write 1s to these unimplemented locations, since they may be used in future microcontrollers to invoke new features. In that case, the reset or inactive values of the new bits will always be 0, and their active values will be 1. ISSI ® The functions of the SFRs are outlined in the following sections, and detailed in Table 2. Accumulator (ACC) ACC is the Accumulator register. The mnemonics for Accumulator-specific instructions, however, refer to the Accumulator simply as A. B Register (B) The B register is used during multiply and divide operations. For other instructions it can be treated as another scratch pad register. Program Status Word (PSW). The PSW register contains program status information. FFH FFH Upper 128 Accessible by Indirect Addressing Only Accessible by Direct Addressing 80H 7FH Accessible by Direct and Indirect Addressing 80H Lower 128 Special Function Registers 0 Ports, Status and Control Bits, Timer, Registers, Stack Pointer, Accumulator (Etc.) F8 F0 E8 E0 D8 D0 C8 C0 B8 B0 A8 A0 98 90 88 80 B ACC PSW T2CON IP P3 IE P2 SCON P1 TCON P0 RCAP2L RCAP2H TL2 TH2 SBUF TMOD SP TL0 DPL TL1 DPH TH0 TH1 PCON FF F7 EF E7 DF D7 CF C7 BF B7 AF A7 9F 97 8F 87 Bit Addressable Figure 6. Internal Data Memory and SFR Memory Map 8 BYTES 78 70 68 60 58 50 48 40 38 30 28 20 18 10 08 00 0 ... BANK3 BANK2 BANK 1 BANK 0 ...7F 7F 77 6F 67 5F 57 4F 47 3F 37 2F 27 1F 17 0F 07 REGISTER BANKS BIT ADDRESSABLE SEGMENT SCRATCH PAD AREA Figure 7. Lower 128 Bytes of Internal RAM 8 Integrated Silicon Solution, Inc. — 1-800-379-4774 MC013-1C 11/21/98 IS89C52 SPECIAL FUNCTION REGISTERS (Continued) Stack Pointer (SP) The Stack Pointer Register is eight bits wide. It is incremented before data is stored during PUSH and CALL executions. While the stack may reside anywhere in onchip RAM, the Stack Pointer is initialized to 07H after a reset. This causes the stack to begin at location 08H. Data Pointer (DPTR) The Data Pointer consists of a high byte (DPH) and a low byte (DPL). Its function is to hold a 16-bit address. It may be manipulated as a 16-bit register or as two independent 8-bit registers. Ports 0 To 3 P0, P1, P2, and P3 are the SFR latches of Ports 0, 1, 2, and 3, respectively. Serial Data Buffer (SBUF) The Serial Data Buffer is actually two separate registers, a transmit buffer and a receive buffer register. When data is moved to SBUF, it goes to the transmit buffer, where it is held for serial transmission. (Moving a byte to SBUF initiates the transmission.) When data is moved from SBUF, it comes from the receive buffer. ISSI ® Timer Registers Register pairs (TH0, TL0) and (TH1, TL1) are the 16-bit Counter registers for Timer/Counters 0 and 1, respectively. Capture Registers The register pair (RCAP2H, RCAP2L) are the Capture registers for the Timer 2 Capture Mode. In this mode, in response to a transition at the IS89C52's T2EX pin, TH2 and TL2 are copied into RCAP2H and RCAP2L. Timer 2 also has a 16-bit auto-reload mode, and RCAP2H and RCAP2L hold the reload value for this mode. Control Registers Special Function Registers IP, IE, TMOD, TCON, SCON, and PCON contain control and status bits for the interrupt system, the Timer/Counters, and the serial port. They are described in later sections of this chapter. Integrated Silicon Solution, Inc. — 1-800-379-4774 MC013-1C 11/21/98 9 IS89C52 Table 2. Special Function Registers Symbol ACC(1) B(1) DPH DPL IE(1) IP(1) P0(1) Description Direct Address E0H F0H 83H 82H A8H B8H 80H E7 F7 Bit Address, Symbol, or Alternative Port Function E6 F6 E5 F5 E4 F4 E3 F3 E2 F2 E1 F1 E0 F0 ISSI Reset Value 00H 00H 00H 00H 0XX00000B XXX00000B FFH ® Accumulator B register Data pointer (DPTR) high Data pointer (DPTR) low Interrupt enable Interrupt priority Port 0 P1(1) P2(1) Port 1 Port 2 90H A0H P3(1) PCON PSW(1) SBUF SCON(1) SP TCON(1) TMOD TH0 TH1 TL0 TL1 RCAP2H(2) RCAP2L(2) TL2(2) Port 3 Power control Program status word Serial data buffer Serial controller Stack pointer Timer control Timer mode Timer high 0 Timer high 1 Timer low 0 Timer low 1 Capture high Capture low Timer low 2 B0H 87H D0H 99H 98H 81H 88H 89H 8CH 8DH 8AH 8BH CAH CBH CCH AF EA BF — 87 P0.7 AD7 97 P1.7 A7 P2.7 AD15 B7 P3.7 RD AE — BE — 86 P0.6 AD6 96 P1.6 A6 P2.6 AD14 B6 P3.6 WR — D6 AC SMOD D7 CY 9F SM0 AD — BD — 85 P0.5 AD5 95 P1.5 A5 P2.5 AD13 B5 P3.5 T1 — D5 F0 9D SM2 8D TF0 M1 AC ES BC PS 84 P0.4 AD4 94 P1.4 A4 P2.4 AD12 B4 P3.4 T0 — D4 RS1 9C REN AB ET1 BB PT1 83 P0.3 AD3 93 P1.3 A3 P2.3 AD11 B3 P3.3 INT1 GF1 D3 RS0 9B TB8 AA EX1 BA PX1 82 P0.2 AD2 92 P1.2 A2 P2.2 AD10 B2 P3.2 A9 ET0 B9 PT0 81 P0.1 AD1 91 P1.1 A1 P2.1 AD9 B1 P3.1 INT0 TXD GF0 PD D2 D1 OV — 9A RB8 8A IT1 C/T 99 TI 89 IE0 M1 A8 EX0 B8 PX0 80 P0.0 AD0 90 P1.0 A0 P2.0 AD8 B0 P3.0 RXD IDL D0 P 98 RI 88 IT0 M0 FFH FFH FFH 0XXX0000B 00H XXXXXXXXB 00H 07H 00H 00H 00H 00H 00H 00H 00H 00H 00H 9E SM1 8F 8E TF1 TR1 GATE C/T 8C 8B TR0 IE1 M0 GATE Notes: 1. Denotes bit addressable. 2. SFRs are added to the 80C51 SFRs. 10 Integrated Silicon Solution, Inc. — 1-800-379-4774 MC013-1C 11/21/98 IS89C52 The detail description of each bit is as follows: ISSI IE: Interrupt Enable Register. Bit Addressable. 1 — 0 P 7 EA 6 — 5 — 4 ES 3 ET1 2 EX1 1 0 ET0 EX0 5 F0 4 RS1 3 RS0 2 OV ® PSW: Program Status Word. Bit Addressable. 7 CY 6 AC Register Description: CY PSW.7 Carry flag. AC PSW.6 Auxiliary carry flag. F0 PSW.5 Flag 0 available to the user for g e n e r a l purpose. RS1 PSW.4 Register bank selector bit 1.(1) RS0 PSW.3 Register bank selector bit 0.(1) OV PSW.2 Overflow flag. — PSW.1 Usable as a general purpose flag P PSW.0 Parity flag. Set/Clear by hardware each instruction cycle to indicate an odd/even number of “1” bits in the accumulator. Note: 1. The value presented by RS0 and RS1 selects the corresponding register bank. RS1 0 0 1 1 RS0 0 1 0 1 Register Bank 0 1 2 3 Address 00H-07H 08H-0FH 10H-17H 18H-1FH Register Description: EA IE.7 Disable all interrupts. If EA=0, no interrupt will be acknowledged. If EA=1, each interrupt source is individually enabled or disabled by setting or clearing its enable bit. — IE.6 Not implemented, reserve for future use.(5) — IE.5 Not implemented, reserve for future use.(5) ES IE.4 Enable or disable the serial port interrupt. ET1 IE.3 Enable or disable the Timer 1 overflow interrupt. EX1 IE.2 Enable or disable External Interrupt 1. ET0 IE.1 Enable or disable the Timer 0 overflow interrupt. EX0 IE.0 Enable or disable External Interrupt 0. Note: To use any of the interrupts in the 80C51 Family, the following three steps must be taken: 1. Set the EA (enable all) bit in the IE register to 1. 2. Set the coresponding individual interrupt enable bit in the IE register to 1. 3. Begin the interrupt service routine at the corresponding Vector Address of that interrupt (see below). PCON: Power Control Register. Not Bit Addressable. 7 SMOD 6 — 5 — 4 — 3 GF1 2 GF0 1 PD 0 IDL Register Description: SMOD Double baud rate bit. If Timer 1 is used to generate baud rate and SMOD=1, the baud rate is doubled when the serial port is used in modes 1, 2, or 3. — Not implemented, reserve for future use.(1) — Not implemented, reserve for future use.(1) — Not implemented, reserve for future use.(1) GF1 General purpose flag bit. GF0 General purpose flag bit. PD Power-down bit. Setting this bit activates powerdown mode. IDL Idle mode bit. Setting this bit activates idle mode. If 1s are written to PD and IDL at the same time, PD takes precedence. Note: 1. User software should not write 1s to reserved bits. These bits may be used in future products to invoke new features. Interrupt Source IE0 TF0 IE1 TF1 RI & TI Vector Address 0003H 000BH 0013H 001BH 0023H 4. In addition, for external interrupts, pins INT0 and INT1 (P3.2 and P3.3) must be set to 1, and depending on whether the interrupt is to be level or transition activated, bits IT0 or IT1 in the TCON register may need to be set to 0 or 1. ITX = 0 level activated (X = 0, 1) ITX = 1 transition activated 5. User software should not write 1s to reserved bits. These bits may be used in future products to invoke new features. Integrated Silicon Solution, Inc. — 1-800-379-4774 MC013-1C 11/21/98 11 IS89C52 IP: Interrupt Priority Register. Bit Addressable. 7 — 6 — 5 — 4 PS 3 PT1 2 PX1 1 0 PT0 PX0 ISSI TCON: Timer/Counter Control Register. Bit Addressable 7 TF1 6 TR1 5 TF0 4 TR0 3 IE1 2 IT1 1 IE0 0 IT0 ® Register Description: — IP.7 Not implemented, reserve for future use(3) — IP.6 Not implemented, reserve for future use(3) — IP.5 Not implemented, reserve for future use(3) PS IP.4 Defines Serial Port interrupt priority level PT1 IP.3 Defines Timer 1 interrupt priority level PX1 IP.2 Defines External Interrupt 1 priority level PT0 IP.1 Defines Timer 0 interrupt priority level PX0 IP.0 Defines External Interrupt 0 priority level Notes: 1. In order to assign higher priority to an interrupt the coresponding bit in the IP register must be set to 1. While an interrupt service is in progress, it cannot be interrupted by a lower or same level interrupt. 2. Priority within level is only to resolve simultaneous requests of the same priority level. From high-to-low, interrupt sources are listed below: IE0 TF0 IE1 TF1 RI or TI TF2 or EXF2 3. User software should not write 1s to reserved bits. These bits may be used in future products to invoke new features. Register Description: TF1 TCON.7 Timer 1 overflow flag. Set by hardware when the Timer/Counter 1 overflows. Cleared by hardware as processor vectors to the interrupt service routine. TR1 TCON.6 Timer 1 run control bit. Set/Cleared by software to turn Timer/Counter 1 ON/ OFF. TF0 TCON.5 Timer 0 overflow flag. Set by hardware when the Timer/Counter 0 overflows. Cleared by hardware as processor vectors to the interrupt service routine. TR0 TCON.4 Timer 0 run control bit. Set/Cleared by software to turn Timer/Counter 0 ON/ OFF. IE1 TCON.3 External Interrupt 1 edge flag. Set by hardware when the External Interrupt edge is detected. Cleared by hardware when interrupt is processed. IT1 TCON.2 Interrupt 1 type control bit. Set/Cleared by software specify falling edge/low level triggered External Interrupt. IE0 TCON.1 External Interrupt 0 edge flag. Set by hardware when the External Interrupt edge is detected. Cleared by hardware when interrupt is processed. IT0 TCON.0 Interrupt 0 type control bit. Set/Cleared by software specify falling edge/low level triggered External Interrupt. 12 Integrated Silicon Solution, Inc. — 1-800-379-4774 MC013-1C 11/21/98 IS89C52 TMOD: Timer/Counter Mode Control Register. Not Bit Addressable. Timer 1 GATE C/T M1 M0 Timer 0 C/T M1 M0 ISSI SCON: Serial Port Control Register. Bit Addressable. 7 6 5 SM0 SM1 SM2 4 REN 3 TB8 2 RB8 1 TI 0 RI ® GATE GATE When TRx (in TCON) is set and GATE=1, TIMER/ COUNTERx will run only while INTx pin is high (hardware control). When GATE=0, TIMER/ COUNTERx will run only while TRx=1 (software control). C/T Timer or Counter selector. Cleared for Timer operation (input from internal system clock). Set for Counter operation (input from Tx input pin). M1 Mode selector bit.(1) M0 Note 1: M1 0 0 1 1 M0 0 1 0 1 Operating Mode Mode 0. (13-bit Timer) Mode 1. (16-bit Timer/Counter) Mode 2. (8-bit auto-load Timer/Counter) Mode 3. (Splits Timer 0 into TL0 and TH0. TL0 is an 8-bit Timer/Counter controller by the standard Timer 0 control bits. TH0 is an 8-bit Timer and is controlled by Timer 1 control bits.) Mode 3. (Timer/Counter 1 stopped). Mode selector bit.(1) 1 1 Register Description: SM0 SCON.7 Serial port mode specifier.(1) SM1 SCON.6 Serial port mode specifier.(1) SM2 SCON.5 Enable the multiprocessor communication feature in mode 2 and 3. In mode 2 or 3, if SM2 is set to 1 then RI will not be activated if the received 9th data bit (RB8) is 0. In mode 1, if SM2=1 then RI will not be activated if valid stop bit was not received. In mode 0, SM2 should be 0. REN SCON.4 Set/Cleared by software to Enable/ Disable reception. TB8 SCON.3 The 9th bit that will be transmitted in mode 2 and 3. Set/Cleared by software. RB8 SCON.2 In modes 2 and 3, RB8 is the 9th data bit that was received. In mode 1, if SM2=0, RB8 is the stop bit that was received. In mode 0, RB8 is not used. TI SCON.1 Transmit interrupt flag. Set by hardware at the end of the eighth bit time in mode 0, or at the beginning of the stop bit in the other modes. Must be cleared by software. RI SCON.0 Receive interrupt flag. Set by hardware at the end of the eighth bit time in mode 0, or halfway through the stop bit time in the other modes (except see SM2). Must be cleared by software. Note 1: SM0 SM1 MODE 0 0 1 1 0 1 0 1 0 1 2 3 Description Shift register 8-bit UART 9-bit UART 9-bit UART Baud Rate Fosc/12 Variable Fosc/64 or Fosc/32 Variable Integrated Silicon Solution, Inc. — 1-800-379-4774 MC013-1C 11/21/98 13 IS89C52 T2CON: Timer/Counter 2 Control Register. Bit Addressable. 7 TF2 6 5 4 3 2 1 0 EXF2 RCLK TCLK EXEN2 TR2 C/T2 CP/RL2 TR2 ISSI ® Register Description: TF2 T2CON.7 Timer 2 overflow flag set by hardware and cleared by software. TF2 cannot be set when either RCLK = 1 or TCLK = 1. EXF2 T2CON.6 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 causes the CPU to vector to the Timer 2 interrupt routine. EXF2 must be cleared by software. RCLK T2CON.5 Receive clock flag. When set, causes the Serial Port to use Timer 2 overflow pulses for its receive clock in modes 1 and 3. RCLK = 0 causes Timer 1 overflow to be used for the receive clock. TLCK T2CON.4 Transmit clock flag. When set, causes the Serial Port to use Timer 2 overflow pulses for its transmit clock in modes 1 and 3. TCLK = 0 causes Timer 1 overflows to be used for the transmit clock. EXEN2 T2CON.3 Timer 2 external enable flag. When set, allows a capture or reload to occur as a result of 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. T2CON.2 Software START/STOP control for Timer 2. A logic 1 starts the Timer. C/T2 T2CON.1 Timer or Counter select. 0 = Internal Timer. 1 = External Event Counter (triggered by falling edge). CP/RL2 T2CON.0 Capture/Reload flag. When set, captures occur on negative transitions at T2EX if EXEN2 = 1. When cleared, auto-reloads occur either with Timer 2 overflows or negative transitions at T2EX when EXEN2 = 1. When either RCLK = 1 or TCLK = 1, this bit is ignored and the Timer is forced to auto-reload on Timer 2 overflow. Note: 1. Timer 2 Operating Modes RCLK + TCLK CP/RL2 TR2 0 0 1 X 0 1 X X 1 1 1 0 MODE 16-Bit Auto-Reload 16-Bit Capture Baud Rate Generator (Off) 14 Integrated Silicon Solution, Inc. — 1-800-379-4774 MC013-1C 11/21/98 IS89C52 TIMER/COUNTERS The IS89C52 has two 16-bit Timer/Counter registers: Timer 0 and Timer 1. All two can be configured to operate either as Timers or event Counters. As a Timer, the register is incremented every machine cycle. Thus, the register counts machine cycles. Since a machine cycle consists of 12 oscillator periods, the count rate is 1/12 of the oscillator frequency. As a Counter, the register is incremented in response to a 1-to-0 transition at its corresponding external input pin, T0 and T1. 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. There are no restrictions on the duty cycle of the external input signal, but it should be held for at least one full machine cycle to ensure that a given level is sampled at least once before it changes. In addition to the Timer or Counter functions, Timer 0 and Timer 1 have four operating modes: 13-bit timer, 16-bit timer, 8-bit auto-reload, split timer. Timer 2 in the IS89C52 has three modes of operation: Capture, Auto-Reoload, and Baud Rate Generator. ISSI Timer 0 and Timer 1 ® The Timer or Counter function is selected by control bits C/T in the Special Function Regiser TMOD. These two Timer/Counters have four operating modes, which are selected by bit pairs (M1, M0) in TMOD. Modes 0, 1, and 2 are the same for both Timer/Counters, but Mode 3 is different. The four modes are described in the following sections. Mode 0: Both Timers in Mode 0 are 8-bit Counters with a divide-by-32 prescaler. Figure 8 shows the Mode 0 operation as it applies to Timer 1. In this mode, the Timer register is configured as a 13-bit register. As the count rolls over from all 1s to all 0s, it sets the Timer interrupt flag TF1. The counted input is enabled to the Timer when TR1 = 1 and either GATE = 0 or INT1 = 1. Setting GATE = 1 allows the Timer to be controlled by external input INT1, to facilitate pulse width measurements. TR1 is a control bit in the Special Function Register TCON. Gate is in TMOD. The 13-bit register consists of all eight bits of TH1 and the lower five bits of TL1. The upper three bits of TL1 are indeterminate and should be ignored. Setting the run flag (TR1) does not clear the registers. Mode 0 operation is the same for Timer 0 as for Timer 1, except that TR0, TF0 and INT0 replace the corresponding Timer 1 signals in Figure 8. There are two different GATE bits, one for Timer 1 (TMOD.7) and one for Timer 0 (TMOD.3). ONE MACHINE ONE MACHINE CYCLE CYCLE S4 S5 S6 S1 S2 S3 S4 S5 S6 S1 S1 S2 S3 P1 P2 P1 P2 P1 P2 P1 P2 P1 P2 P1 P2 P1 P2 P1 P2 P1 P2 P1 P2 P1 P2 P1 P2 P1 P2 OSC (XTAL2) OSC DIVIDE 12 C/T = 0 TL1 (5 BITS) T1 PIN TR1 GATE INT1 PIN C/T = 1 CONTROL TH1 (8 BITS) TF1 INTERRUPT Figure 8. Timer/Counter 1 Mode 0: 13-Bit Counter Integrated Silicon Solution, Inc. — 1-800-379-4774 MC013-1C 11/21/98 15 IS89C52 Mode 1: Mode 1 is the same as Mode 0, except that the Timer register is run with all 16 bits. The clock is applied to the combined high and low timer registers (TL1/TH1). As clock pulses are received, the timer counts up: 0000H, 0001H, 0002H, etc. An overflow occurs on the FFFFH-to-0000H overflow flag. The timer continues to count. The overflow flag is the TF1 bit in TCON that is read or written by software (see Figure 9). Mode 2: Mode 2 configures the Timer register as an 8-bit Counter (TL1) with automatic reload, as shown in Figure 10. Overflow from TL1 not only sets TF1, but also reloads TL1 with the contents of TH1, which is preset by software. The reload leaves the TH1 unchanged. Mode 2 operation is the same for Timer/Counter 0. ISSI ® Mode 3: Timer 1 in Mode 3 simply holds its count. The effect is the same as setting TR1 = 0. Timer 0 in Mode 3 establishes TL0 and TH0 as two separate counters. The logic for Mode 3 on Timer 0 is shown in Figure 11. TL0 uses the Timer 0 control bits: C/T, GATE, TR0, INT0, and TF0. TH0 is locked into a timer function (counting machine cycles) and over the use of TR1 and TF1 from Timer 1. Thus, TH0 now controls the Timer 1 interrupt. Mode 3 is for applications requiring an extra 8-bit timer or counter. With Timer 0 in Mode 3, the IS89C52 can appear to have four Timer/Counters. When Timer 0 is in Mode 3, Timer 1 can be turned on and off by switching it out of and into its own Mode 3. In this case, Timer 1 can still be used by the serial port as a baud rate generator or in any application not requiring an interrupt. TIMER CLOCK TL1 (8 BITS) TH1 (8 BITS) TF1 OVERFLOW FLAG Figure 9. Timer/Counter 1 Mode 1: 16-Bit Counter OSC DIVIDE 12 C/T = 0 TL1 (8 BITS) T1 PIN TR1 GATE INT0 PIN C/T = 1 CONTROL RELOAD TF1 INTERRUPT TH1 (8 BITS) Figure 10. Timer/Counter 1 Mode 2: 8-Bit Auto-Reload 16 Integrated Silicon Solution, Inc. — 1-800-379-4774 MC013-1C 11/21/98 IS89C52 ISSI DIVIDE 12 1/12 FOSC ® OSC 1/12 FOSC C/T = 0 TL0 (8 BITS) TF0 INTERRUPT T0 PIN TR0 GATE INT0 PIN 1/12 FOSC TR1 C/T = 1 CONTROL TH0 (8 BITS) CONTROL TF1 INTERRUPT Figure 11. Timer/Counter 0 Mode 3: Two 8-Bit Counters Timer 2 This is a powerful addition to the other two just discussed. Five extra special function registers are added to accommodate Timer 2 which are: the timer registers, TL2 and TH2, the timer control register, T2CON, and the capture registers, RCAP2L and RCAP2H. Like Timers 0 and 1, it can operate either as a timer or as an event counter, depending on the value of bit C/T2 in the Special Function Register T2CON. Timer 2 has three operating modes: capture, auto-reload, and baud rate generator, which are selected by RCLK, TCLK, CP/RL2, and TR2. In the Capture Mode, the EXEN2 bit in T2CON selects two options. If EXEN2 = 0, then Timer 2 is a 16-bit timer or counter whose overflow sets bit TF2, the Timer 2 overflow bit, which can be used to generate an interrupt. If EXEN2 = 1, then Timer 2 performs the same way, but a 1-to-0 transition at external input T2EX also causes the current value in the Timer 2 registers, TL2 and TH2, to be captured into the RCAP2L and RCAP2H registers, respectively. In addition, the transition at T2EX sets the EXF2 bit in T2CON, and EXF2, like TF2, can generate an interrupt. The Capture Mode is illustrated in Figure 12. In the auto-reload mode, the EXEN2 bit in T2CON also selects two options. If EXEN2 = 0, then when Timer 2 rolls over it sets TF2 and also reloads the Timer 2 registers with the 16-bit value in the RCAP2L and RCAP2H registers, which are preset by software. If EXEN2 = 1, then Timer 2 performs the same way, but a 1-to-0 transition at external input T2EX also triggers the 16-bit reload and sets EXF2. The auto-reload mode is illustrated in Figure 13. The baud rate generator mode is selected by RCLK = 1 and/or TCLK = 1. This mode is described in conjunction with the serial port (see Figure 14). Integrated Silicon Solution, Inc. — 1-800-379-4774 MC013-1C 11/21/98 17 IS89C52 ISSI OSC DIVIDE 12 C/T2 = 0 TL2 (8 BITS) T2 PIN C/T2 = 1 CONTROL ® TH2 (8 BITS) TF2 TR2 CAPTURE TIMER 2 INTERRUPT RCAP2L RCAP2H EXF2 TRANSITION DETECTOR T2EX PIN CONTROL EXEN2 Figure 12. Timer 2 In Capture Mode OSC DIVIDE 12 C/T2 = 0 TL2 (8 BITS) TH2 (8 BITS) T2 PIN C/T2 = 1 CONTROL TR2 RELOAD TRANSITION DETECTOR T2EX PIN CONTROL RCAP2L RCAP2H TF2 TIMER 2 INTERRUPT EXF2 EXEN2 Figure 13. Timer 2 in Auto-Reload Mode TIMER 1 OVERFLOW NOTE: OSC FREQ. IS DIV BY 2, NOT 12 DIVIDE 2 "0" "1" SMOD TL2 (8 BITS) TH2 (8 BITS) "1" "0" RCLK DIVIDE 16 RELOAD RCAP2L RCAP2H "1" "0" TCLK RX CLOCK OSC DIVIDE 2 C/T2 = 0 T2 PIN C/T2 = 1 CONTROL TR2 TRANSITION DETECTOR T2EX PIN CONTROL EXEN2 EXF2 DIVIDE 16 TX CLOCK TIMER 2 INTERRUPT Figure 14. Timer 2 in Baud Rate Generator Mode Note: T2EX can be used as an additional external interrupt. 18 Integrated Silicon Solution, Inc. — 1-800-379-4774 MC013-1C 11/21/98 IS89C52 Timer Setup Tables 3 through 6 give TMOD values that can be used to set up Timers in different modes. It assumes that only one timer is used at a time. If Timers 0 and 1 must run simultaneously in any mode, the value in TMOD for Timer 0 must be ORed with the value shown for Timer 1 (Tables 5 and 6). For example, if Timer 0 must run in Mode 1 GATE (external control), and Timer 1 must run in Mode 2 COUNTER, then the value that must be loaded into TMOD is 69H (09H from Table 3 ORed with 60H from Table 6). Moreover, it is assumed that the user is not ready at this point to turn the timers on and will do so at another point in the program by setting bit TRx (in TCON) to 1. Table 3. Timer/Counter 0 Used as a Timer Mode 0 1 2 3 Timer 0 Function 13-Bit Timer 16-Bit Timer 8-Bit Auto-Reload Two 8-Bit Timers TMOD Internal External Control(1) Control(2) 00H 01H 02H 03H 08H 09H 0AH 0BH Table 5. Timer/Counter 1 Used as a Timer Mode 0 1 2 3 Timer 1 Function 13-Bit Timer 16-Bit Timer 8-Bit Auto-Reload Does Not Run ISSI ® TMOD Internal External Control(1) Control(2) 00H 10H 20H 30H 80H 90H A0H B0H Table 6. Timer/Counter 1 Used as a Counter Mode 0 1 2 3 Timer 1 Function 13-Bit Timer 16-Bit Timer 8-Bit Auto-Reload Not Available TMOD Internal External Control(1) Control(2) 40H 50H 60H — C0H D0H E0H — Notes: 1. The Timer is turned ON/OFF by setting/clearing bit TR1 in the software. 2. The Timer is turned ON/OFF by the 1-to-0 transition on INT1 (P3.3) when TR1 = 1 (hardware control). Table 4. Timer/Counter 0 Used as a Counter Mode 0 1 2 3 Timer 0 Function 13-Bit Timer 16-Bit Timer 8-Bit Auto-Reload One 8-Bit Counter TMOD Internal External Control(1) Control(2) 04H 05H 06H 07H 0CH 0DH 0EH 0FH Notes: 1. The Timer is turned ON/OFF by setting/clearing bit TR0 in the software. 2. The Timer is turned ON/OFF by the 1 to 0 transition on INT0 (P3.2) when TR0 = 1 (hardware control). Integrated Silicon Solution, Inc. — 1-800-379-4774 MC013-1C 11/21/98 19 IS89C52 Timer/Counter 2 Set-Up Except for the baud rate generator mode, the values given for T2C0N do not include the setting of the TR2 bit. Therefore, bit TR2 must be set separately to turn the Timer on. Table 7. Timer/Counter 2 Used as a Timer Mode 16-Bit Auto-Reload 16-Bit Capture Baud Rate Generator Receive and Transmit Same Baud Rate Receive Only Transmit Only T2CON Internal External Control(1) Control(2) 00H 01H 34H 24H 14H 08H 09H 36H 26H 16H ISSI SERIAL INTERFACE ® The Serial port is full duplex, which means it can transmit and receive simultaneously. It is also receive-buffered, which means it can begin receiving a second byte before a previously received byte has been read from the receive register. (However, if the first byte still has not been read when reception of the second byte is complete, one of the bytes will be lost.) The serial port receive and transmit registers are both accessed at Special Function Register SBUF. Writing to SBUF loads the transmit register, and reading SBUF accesses a physically separate receive register. The serial port can operate in the following four modes: Mode 0: Serial data enters and exits through RXD. TXD outputs the shift clock. Eight data bits are transmitted/received, with the LSB first. The baud rate is fixed at 1/12 the oscillator frequency (see Figure 15). Mode 1: Ten bits are transmitted (through TXD) or received (through RXD): a start bit (0), eight data bits (LSB first), and a stop bit (1). On receive, the stop bit goes into RB8 in Special Function Register SCON. The baud rate is variable (see Figure 16). Mode 2: Eleven bits are transmitted (through TXD) or received (through RXD): a start bit (0), eight data bits (LSB first), a programmable ninth data bit, and a stop bit (1). On transmit, the ninth data bit (TB8 in SCON) can be assigned the value of 0 or 1. Or, for example, the parity bit (P, in the PSW) can be moved into TB8. On receive, the ninth data bit goes into RB8 in Special Function Register SCON, while the stop bit is ignored. The baud rate is programmable to either 1/32 or 1/64 the oscillator frequency (see Figure 17). Mode 3: Eleven bits are transmitted (through TXD) or received (through RXD): a start bit (0), eight data bits (LSB first), a programmable ninth data bit, and a stop bit (1). In fact, Mode 3 is the same as Mode 2 in all respects except the baud rate, which is variable in Mode 3 (see Figure 18). In all four modes, transmission is initiated by any instruction that uses SBUF as a destination register. Reception is initiated in Mode 0 by the condition RI = 0 and REN = 1. Reception is initiated in the other modes by the incoming start bit if REN = 1. Table 8. Timer/Counter 2 Used as a Counter Mode 16-Bit Auto-Reload 16-Bit Capture TMOD Internal External Control(1) Control(2) 02H 03H 0AH 0BH Notes: 1. Capture/Reload occurs only on Timer/Counter overflow. 2. Capture/Reload occurs on Timer/Counter overflow and a 1-to-0 transition on T2EX (P1.1) pin except when Timer 2 is used in the baud rate generating mode. 20 Integrated Silicon Solution, Inc. — 1-800-379-4774 MC013-1C 11/21/98 IS89C52 Multiprocessor Communications Modes 2 and 3 have a special provision for multiprocessor communications. In these modes, nine data bits are received, followed by a stop bit. The ninth bit goes into RB8; then comes a stop bit. The port can be programmed such that when the stop bit is received, the serial port interrupt is activated only if RB8 = 1. This feature is enabled by setting bit SM2 in SCON. The following example shows how to use the serial interrupt for multiprocessor communications. When the master processor must transmit a block of data to one of several slaves, it first sends out an address byte that identifies the target slave. An address byte differs from a data byte in that the ninth bit is 1 in an address byte and 0 in a data byte. With SM2 = 1, no slave is interrupted by a data byte. An address byte, however, interrupts all slaves, so that each slave can examine the received byte and see if it is being addressed. The addressed slave clears its SM2 bit and prepares to receive the data bytes that follows. The slaves that are not addressed set their SM2 bits and ignore the data bytes. SM2 has no effect in Mode 0 but can be used to check the validity of the stop bit in Mode 1. In a Mode 1 reception, if SM2 = 1, the receive interrupt is not activated unless a valid stop bit is received. ISSI ® Using the Timer 1 to Generate Baud Rates When Timer 1 is the baud rate generator, the baud rates in Modes 1 and 3 are determined by the Timer 1 overflow rate and the value of SMOD according to the following equation. Mode 1, 3 = Baud Rate 2SMOD 32 X (Timer 1 Overflow Rate) The Timer 1 interrupt should be disabled in this application. The Timer itself can be configured for either timer or counter operation in any of its three running modes. In the most typical applications, it is configured for timer operation in auto-reload mode (high nibble of TMOD = 0010B). In this case, the baud rate is given by the following formula. Mode 1,3 = Baud Rate 2SMOD 32 Oscillator Frequency 12x [256 – (TH1)] X Programmers can achieve very low baud rates with Timer 1 by leaving the Timer 1 interrupt enabled, configuring the Timer to run as a 16-bit timer (high nibble of TMOD = 0001B), and using the Timer 1 interrupt to do a 16-bit software reload. Table 9 lists commonly used baud rates and how they can be obtained from Timer 1. Baud Rates The baud rate in Mode 0 is fixed as shown in the following equation. Oscillator Frequency 12 The baud rate in Mode 2 depends on the value of the SMOD bit in Special Function Register PCON. If SMOD = 0 (the value on reset), the baud rate is 1/64 of the oscillator frequency. If SMOD = 1, the baud rate is 1/32 of the oscillator frequency, as shown in the following equation. Mode 0 Baud Rate = Mode 2 Baud Rate = 2SMOD x (Oscillator Frequency) 64 In the IS89C52, these baud rates can be determined by Timer 1, Timer 2, or both (one for transmit and the other for receive). Integrated Silicon Solution, Inc. — 1-800-379-4774 MC013-1C 11/21/98 21 IS89C52 Using Timer 2 to Generate Baud Rates In the IS89C52, setting TCLK and/or RCLK in T2CON selects Timer 2 as the baud rate generator. Under these conditions, the baud rates for transmit and receive can be simultaneously different. Setting RCLK and/or TCLK puts Timer 2 into its baud rate generator mode, as shown in Figure 14. The baud rate generator mode is similar to the auto-reload mode, in that a rollover in TH2 reloads the Timer 2 registers with the 16-bit value in the RCAP2H and RCAP2L registers, which are preset by software. In this case, the baud rates in Mode 1 and 3 are determined by the Timer 2 overflow rate according to the following equation. Timer 2 Overflow Rate 16 Timer 2 can be configured for either timer or counter operation. In the most typical applications, it is configured for timer operation (C/T2 = 0). Normally, a timer increments every machine cycle (thus, at 1/12 the oscillator frequency), but timer operation is a different for Timer 2 when it is used as a baud rate generator. As a baud rate generator, Timer 2 increments every state time (thus at 1/2 the oscillator frequency). In this case, the baud rate is given by the following formula. Modes 1, 3 Baud Rate = Modes 1, 3 Baud Rate Oscillator Frequency 32x [65536 – (RCAP2H, RCAP2L)] ISSI ® Where (RCAP2H, RCAP2L) is the content of RCAP2H and RCAP2L taken as a 16-bit unsigned integer. Figure 13 shows Timer 2 as a baud rate generator. This figure is valid only if RCLK + TCLK = 1 in T2CON. A rollover in TH2 does not set TF2 and does no generate an interrupt. Therefore, the Timer 2 interrupt does not have to be disabled when Timer 2 is in the baud rate generator mode. If EXEN2 is set, a 1-to-0 transition in T2EX sets EXF2 but does not cause a reload from (RCAP2H, RCAP2L) to (TH2, TL2). Thus, when Timer 2 is used as a baud rate generator, T2EX can be used as an extra external interrupt. When Timer 2 is running (TR2 = 1) as a timer in the baud rate generator mode, programmers should not read from or write to TH2 or TL2. Under these conditions, Timer 2 is incremented every state time, and the results of a read or write may not be accurate. The RCAP registers may be read, but should not be written to, because a write might overlap a reload and cause write and/or reload errors. Turn Timer 2 off (clear TR2) before accessing the Timer 2 or RCAP registers, in this case. = Table 9. Commonly Used Baud Rates Generated by Timer 1 Timer 1 Baud Rate Mode 0 Max: 1 MHz Mode 2 Max: 375K Modes 1, 3: 62.5K 19.2K 9.6K 4.8K 2.4K 1.2K 137.5 110 110 fOSC 12 MHz 12 MHz 12 MHz 11.059 MHz 11.059 MHz 11.059 MHz 11.059 MHz 11.059 MHz 11.986 MHz 6 MHz 12 MHz SMOD X 1 1 1 0 0 0 0 0 0 0 C/T X X 0 0 0 0 0 0 0 0 0 Mode X X 2 2 2 2 2 2 2 2 1 Reload Value X X FFH FDH FDH FAH F4H E8H 1DH 72H FEEBH 22 Integrated Silicon Solution, Inc. — 1-800-379-4774 MC013-1C 11/21/98 IS89C52 More About Mode 0 Serial data enters and exits through RXD. TXD outputs the shift clock. Eight data bits are transmitted/received, with the LSB first. The baud rate is fixed at 1/12 the oscillator frequency. Figure 15 shows a simplified functional diagram of the serial port in Mode 0 and associated timing. Transmission is initiated by any instruction that uses SBUF as a destination register. The "write to SBUF" signal at S6P2 also loads a 1 into the ninth position of the transmit shift register and tells the TX Control block to begin a transmission. The internal timing is such that one full machine cycle will elapse between "write to SBUF" and activation of SEND. SEND transfer the output of the shift register to the alternate output function line of P3.0, and also transfers SHIFT CLOCK to the alternate output function line of P3.1. SHIFT CLOCK is low during S3, S4, and S5 of every machine cycle, and high during S6, S1, and S2. At S6P2 of every machine cycle in which SEND is active, the contents of the transmit shift register are shifted one position to the right. As data bits shift out to the right, 0s come in from the left. When the MSB of the data byte is at the output position of the shift register, the 1 that was initially loaded into the ninth position is just to the left of the MSB, and all positions to the left of that contain 0s. This condition flags the TX Control block to do one last shift, then deactivate SEND and set TI. Both of these actions occur at S1P1 of the tenth machine cycle after "write to SBUF." Reception is initiated by the condition REN = 1 and RI = 0. At S6P2 of the next machine cycle, the RX Control unit writes the bits 11111110 to the receive shift register and activates RECEIVE in the next clock phase. RECEIVE enables SHIFT CLOCK to the alternate output function line of P3.1. SHIFT CLOCK makes transitions at S3P1 and S6P1 of every machine cycle. At S6P2 of every machine cycle in which RECEIVE is active, the contents of the receive shift register are shifted on position to the left. The value that comes in from the right is the value that was sampled at the P3.0 pin at S5P2 of the same machine cycle. As data bits come in from the right, 1s shift out to the left. When the 0 that was initially loaded into the right-most position arrives at the left-most position in the shift register, it flags the RX Control block to do one last shift and load SBUF. At S1P1 of the tenth machine cycle after the write to SCON that cleared RI, RECEIVE is cleared and RI is set. ISSI ® More About Mode 1 Ten bits are transmitted (through TXD), or received (through RXD): a start bit (0), eight data bits (LSB first), and a stop bit (1). On receive, the stop bit goes into RB8 in SCON. In the IS89C52 the baud rate is determined by the Timer 1 overflow rate. Figure 16 shows a simplified functional diagram of the serial port in Mode 1 and associated timings for transmit and receive. Transmission is initiated by any instruction that uses SBUF as a destination register. The "write to SBUF" signal also loads a 1 into the ninth bit position of the transmit shift register and flags the TX control unit that a transmission is requested. Transmission actually commences at S1P1 of the machine cycle following the next rollover in the divide-by-16 counter. Thus, the bit times are synchronized to the divide-by-16 counter, not to the "write to SBUF" signal. The transmission begins when SEND is activated, which puts the start bit at TXD. One bit time later, DATA is activated, which enables the output bit of the transmit shift register to TXD. The first shift pulse occurs one bit time after that. As data bits shift out to the right, 0s are clocked in from the left. When the MSB of the data byte is at the output position of the shift register, the 1 that was initially loaded into the ninth position is just to the left of the MSB, and all positions to the left of that contain 0s. This condition flags the TX Control unit to do one last shift, then deactivate SEND and set TI. This occurs at the tenth divide-by-16 rollover after "write to SBUF". Reception is initiated by a 1-to-0 transition detected at RXD. For this purpose, RXD is sampled at a rate of 16 times the established baud rate. When a transition is detected, the divide-by-16 counter is immediately reset, and 1FFH is written into the input shift register. Resetting the divide-by-16 counter aligns its rollovers with the boundaries of the incoming bit times. The 16 states of the counter divide each bit time into 16th. At the seventh, eighth, and ninth counter states of each bit time, the bit detector samples the value of RXD. The value accepted is the value that was seen in at least two of the three samples. This is done to reject noise. In order to reject false bits, if the value accepted during the first bit time is not 0, the receive circuits are reset and the unit continues looking for another 1-to-0 transition. If the start bit is valid, it is shifted into the input shift register, and reception of the rest of the frame proceeds. Integrated Silicon Solution, Inc. — 1-800-379-4774 MC013-1C 11/21/98 23 IS89C52 As data bits come in from the right, 1s shift to the left. When the start bit arrives at the leftmost position in the shift register, (which is a 9-bit register in Mode 1), it flags the RX Control block to do one last shift, load SBUF and RB8, and set RI. The signal to load SBUF and RB8 and to set RI is generated if, and only if, the following conditions are met at the time the final shift pulse is generated. 1) RI = 0 and 2) Either SM2 = 0, or the received stop bit =1 If either of these two conditions is not met, the received frame is irretrievably lost. If both conditions are met, the stop bit goes into RB8, the eight data bits go into SBUF, and RI is activated. At this time, whether or not the above conditions are met, the unit continues looking for a 1-to-0 transition in RXD. More About Modes 2 and 3 Eleven bits are transmitted (through TXD), or received (through RXD): a start bit (0), eight data bits (LSB first), a programmable ninth data bit, and a stop bit (1). On transmit, the ninth data bit (TB8) can be assigned the value of 0 or 1. On receive, the ninth data bit goes into RB8 in SCON. The baud rate is programmable to either 1/32 or 1/64 of the oscillator frequency in Mode 2. Mode 3 may have a variable baud rate generated from Timer 1. Figures 17 and 18 show a functional diagram of the serial port in Modes 2 and 3. The receive portion is exactly the same as in Mode 1. The transmit portion differs from Mode 1 only in the ninth bit of the transmit shift register. Transmission is initiated by any instruction that uses SBUF as a destination register. The "write to SBUF" signal also loads TB8 into the ninth bit position of the transmit shift register and flags the TX Control unit that a transmission is requested. Transmission commences at S1P1 of the machine cycle following the next rollover in the divide-by16 counter. Thus, the bit times are synchronized to the divide-by-16 counter, not to the "write to SBUF" signal. The transmission begins when SEND is activated, which puts the start bit at TXD. One bit timer later, DATA is activated, which enables the output bit of the transmit shift register to TXD. The first shift pulse occurs one bit time after that. The first shift clocks a 1 (the stop bit) into the ninth bit position of the shift register. Thereafter, only 0s are clocked in. Thus, as data bits shift out to the right, 0s are clocked in from the left. When TB8 is at the output position of the shift register, then the stop bit is just to the left of TB8, and all positions to the left of that contain 0s. This condition flags the TX Control unit to do one last shift, then deactivate SEND and set TI. This occurs at the eleventh divide-by-16 rollover after "write to SBUF". ISSI ® Reception is initiated by a 1-to-0 transition detected at RXD. For this purpose, RXD is sampled at a rate of 16 times the established baud rate. When a transition is detected, the divide-by-16 counter is immediately reset, and 1FFH is written to the input shift register. At the seventh, eighth, and ninth counter states of each bit time, the bit detector samples the value of RXD. The value accepted is the value that was seen in at least two of the three samples. If the value accepted during the first bit time is not 0, the receive circuits are reset and the unit continues looking for another 1-to-0 transition. If the start bit proves valid, it is shifted into the input shift register, and reception of the rest of the frame proceeds. As data bits come in from the right, 1s shift out to the left. When the start bit arrives at the leftmost position in the shift register (which in Modes 2 and 3 is a 9-bit register), it flags the RX Control block to do one last shift, load SBUF and RB8, and set RI. The signal to load SBUF and RB8 and to set RI is generated if, and only if, the following conditions are met at the time the final shift pulse is generated: 1) RI = 0, and 2) Either SM2 = 0 or the received ninth data bit = 1 If either of these conditions is not met, the received frame is irretrievably lost, and RI is not set. If both conditions are met, the received ninth data bit goes into RB8, and the first eight data bits go into SBUF. One bit time later, whether the above conditions were met or not, the unit continues looking for a 1-to-0 transition at the RXD input. Note that the value of the received stop bit is irrelevant to SBUF, RB8, or RI. Table 10. Serial Port Setup Mode 0 1 2 3 0 1 2 3 SCON 10H 50H 90H D0H NA 70H B0H F0H Multiprocessor Environment (SM2 = 1) SM2Variation Single Processor Environment (SM2 = 0) 24 Integrated Silicon Solution, Inc. — 1-800-379-4774 MC013-1C 11/21/98 IS89C52 ISSI IS89C52 INTERNAL BUS ® WRITE TO SBUF S DQ CL SBUF SHIFT ZERO DETECTOR RXD P3.0 ALT OUTPUT FUNCTION START TX CONTROL S6 SERIAL PORT INTERRUPT RX CLOCK REN RI START RI RX CONTROL TX CLOCK SHIFT SEND TXD P3.1 ALT OUTPUT FUNCTION SHIFT CLOCK RECEIVE SHIFT 11111110 RXD P3.0 ALT INPUT FUNCTION SHIFT INPUT SHIFT REG. LOAD SBUF SBUF READ SBUF IS89C52 INTERNAL BUS S4 S5 S6 S1 S2 S3 S4 S5 S6 S1 S2 S3 S4 S5 S6 S1 S2 S3 S4 S5 S6 S1 S2 S3 S4 S5 S6 S1 S2 S3 S4 S5 S6 S1 S2 S3 S4 S5 S6 S1 S2 S3 S4 S5 S6 S1 S2 S3 S4 S5 S6 S1 S2 S3 S4 S5 S6 S1 S2 S3 S4 S5 S6 S1 ALE WRITE TO SBUF SEND SHIFT S6P2 RXD (DOUT) TXD (SHIFT CLOCK) TI D0 D1 D2 D3 D4 D5 D6 D7 TRANSMIT S3P1 S6P1 WRITE TO SCON (CLEAR RI) RI RECEIVE SHIFT RXD (DIN) D0 D1 D2 D3 D4 D5 D6 D7 RECEIVE S5P2 TXD (SHIFT CLOCK) Figure 15. Serial Port Mode 0 Integrated Silicon Solution, Inc. — 1-800-379-4774 MC013-1C 11/21/98 25 IS89C52 ISSI IS89C52 INTERNAL BUS TB8 TIMER 1 OVERFLOW TIMER 2 OVERFLOW WRITE TO SBUF SMOD =1 ® ÷2 SMOD =0 S DQ CL SBUF TXD ZERO DETECTOR "0" TCLK "1" ÷ 16 SHIFT DATA TX CONTROL RX CLOCK SEND TI START SERIAL PORT INTERRUPT "0" RCLK "1" ÷ 16 SAMPLE 1-TO-0 TRANSITION DETECTOR RX CLOCK START RI RX CONTROL LOAD SBUF SHIFT 1FFH BIT DETECTOR INPUT SHIFT REG. (9 BITS) LOAD SBUF SHIFT RXD SBUF READ SBUF IS89C52 INTERNAL BUS TX CLOCK WRITE TO SBUF SEND DATA SHIFT TXD TI RX CLOCK RXD RECEIVE ÷ 16 RESET START BIT START BIT D0 D1 D2 D3 D4 D5 D6 D7 S1P1 TRANSMIT STOP BIT D0 D1 D2 D3 D4 D5 D6 D7 STOP BIT BIT DETECTOR SAMPLE TIMES SHIFT RI Figure 16. Serial Port Mode 1 26 Integrated Silicon Solution, Inc. — 1-800-379-4774 MC013-1C 11/21/98 IS89C52 IS89C52 INTERNAL BUS TB8 ISSI ® WRITE TO SBUF S DQ CL SBUF TXD ZERO DETECTOR PHASE 2 CLOCK (1/2 fOSC) MODE 2 SMOD 1 ÷2 SMOD 0 (SMOD IS PCON. 7) SAMPLE 1-TO-0 TRANSITION DETECTOR START RI RX CLOCK RX CONTROL LOAD SBUF SHIFT 1FFH ÷ 16 ÷ 16 START STOP BIT GEN SHIFT DATA TX CONTROL TX CLOCK SEND TI SERIAL PORT INTERRUPT BIT DETECTOR INPUT SHIFT REG. (9 BITS) LOAD SBUF SHIFT RXD SBUF READ SBUF IS89C52 INTERNAL BUS TX CLOCK WRITE TO SBUF SEND DATA SHIFT TXD TI STOP BIT GEN RX CLOCK RXD RECEIVE BIT DETECTOR SAMPLE TIMES SHIFT RI ÷ 16 RESET START BIT START BIT D0 D1 D2 D3 D4 D5 D6 D7 TB8 S1P1 TRANSMIT STOP BIT D0 D1 D2 D3 D4 D5 D6 D7 RB8 STOP BIT Figure 17. Serial Port Mode 2 Integrated Silicon Solution, Inc. — 1-800-379-4774 MC013-1C 11/21/98 27 IS89C52 ISSI IS89C52 INTERNAL BUS TB8 TIMER 1 OVERFLOW TIMER 2 OVERFLOW WRITE TO SBUF SMOD =1 ® ÷2 SMOD =0 S DQ CL SBUF TXD ZERO DETECTOR "0" TCLK "1" ÷ 16 SHIFT DATA TX CONTROL TX CLOCK SEND TI START SERIAL PORT INTERRUPT ÷ 16 "0" RCLK "1" SAMPLE 1-TO-0 TRANSITION DETECTOR RX CLOCK START RI RX CONTROL LOAD SBUF SHIFT 1FFH BIT DETECTOR INPUT SHIFT REG. (9 BITS) LOAD SBUF SHIFT RXD SBUF READ SBUF IS89C52 INTERNAL BUS TX CLOCK WRITE TO SBUF SEND DATA SHIFT TXD TI STOP BIT GEN RX CLOCK RXD RECEIVE BIT DETECTOR SAMPLE TIMES SHIFT RI ÷ 16 RESET START BIT START BIT D0 D1 D2 D3 D4 D5 D6 D7 TB8 S1P1 TRANSMIT STOP BIT D0 D1 D2 D3 D4 D5 D6 D7 RB8 STOP BIT Figure 18. Serial Port Mode 3 28 Integrated Silicon Solution, Inc. — 1-800-379-4774 MC013-1C 11/21/98 IS89C52 INTERRUPT SYSTEM The IS89C52 provides six interrupt sources: two external interrupts, two timer interrupts, and a serial port interrupt. These are shown in Figure 19. The External Interrupts INT0 and INT1 can each be either level-activated or transition-activated, depending on bits IT0 and IT1 in Register TCON. The flags that actually generate these interrupts are the IE0 and IE1 bits in TCON. When the service routine is vectored, hardware clears the flag that generated an external interrupt only if the interrupt was transition-activated. If the interrupt was level-activated, then the external requesting source (rather than the on-chip hardware) controls the request flag. The Timer 0 and Timer 1 Interrupts are generated by TF0 and TF1, which are set by a rollover in their respective Timer/Counter registers (except for Timer 0 in Mode 3). When a timer interrupt is generated, the on-chip hardware clears the flag that generated it when the service routine is vectored to. The Serial Port Interrupt is generated by the logical OR of RI and TI. Neither of these flags is cleared by hardware ISSI ® when the service routine is vectored to. In fact, the service routine normally must determine whether RI or TI generated the interrupt, and the bit must be cleared in software. In the IS89C52, the Timer 2 Interrupt is generated by the logical OR of TF2 and EXF2. 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 TF2 or EXF2 generated the interrupt, and the bit must be cleared in software. All of the bits that generate interrupts can be set or cleared by software, with the same result as though they had been set or cleared by hardware. That is, interrupts can be generated and pending interrupts can be canceled in software. Each of these interrupt sources can be individually enabled or disabled by setting or clearing a bit in Special Function Register IE (interrupt enable) at address 0A8H. As well as individual enable bits for each interrupt source, there is a global enable/disable bit that is cleared to disable all interrupts or set to turn on interrupts (see SFR IE). POLLING HARDWARE TCON.1 INT0 EXTERNAL INT RQST 0 IE0 TCON.5 TIMER/COUNTER 0 TF0 TCON.3 INT1 EXTERNAL INT RQST 1 IE1 TCON.7 TIMER/COUNTER 1 TF1 SCON.0 INTERNAL RI SERIAL SCON.1 PORT TI TIMER/ COUNTER 2 T2CON.7 TF2 T2CON.6 EXF2 IE.0 IE.7 IP.0 HIGH PRIORITY INTERRUPT REQUEST EX0 IE.1 PX0 IP.1 ET0 IE.2 PT0 IP.2 SOURCE I.D. VECTOR EX1 IE.3 PX1 IP.3 ET1 IE.4 PT1 IP.4 LOW PRIORITY INTERRUPT REQUEST ES IE.5 PS IP.5 T2EX ET2 EA PT2 SOURCE I.D. VECTOR Figure 19. Interrupt System Integrated Silicon Solution, Inc. — 1-800-379-4774 MC013-1C 11/21/98 29 IS89C52 Priority Level Structure Each interrupt source can also be individually programmed to one of two priority levels by setting or clearing a bit in Special Function Register IP (interrupt priority) at address 0B8H. IP is cleared after a system reset to place all interrupts at the lower priority level by default. A lowpriority interrupt can be interrupted by a high-priority interrupt but not by another low-priority interrupt. A highpriority interrupt can not be interrupted by any other interrupt source. If two requests of different priority levels are received simultaneously, the request of higher priority level is serviced. If requests of the same priority level are received simultaneously, an internal polling sequence determines which request is serviced. Thus, within each priority level there is a second priority structure determined by the polling sequence, as follows: Source IE0 TF0 IE1 TF1 RI + TI Priority Within Level (Highest) ISSI ® cycle will find it and the interrupt system will generate an LCALL to the appropriate service routine, provided this hardware generated LCALL is not blocked by any of the following conditions: 1. An interrupt of equal or higher priority level is already in progress. 2. The current (polling) cycle is not the final cycle in the execution of the instruction in progress. 3. The instruction in progress is RETI or any write to the IE or IP registers. Any of these three conditions will block the generation of the LCALL to the interrupt service routine. Condition 2 ensures that the instruction in progress will be completed before vectoring to any service routine. Condition 3 ensures that if the instruction in progress is RETI or any access to IE or IP, then at least one more instruction will be executed before any interrupt is vectored to. The polling cycle is repeated with each machine cycle, and the values polled are the values that were present at S5P2 of the previous machine cycle. If an active interrupt flag is not being serviced because of one of the above conditions and is not still active when the blocking condition is removed, the denied interrupt will not be serviced. In other words, the fact that the interrupt flag was once active but not serviced is not remembered. Every polling cycle is new. The polling cycle/LCALL sequence is illustrated in Figure 20. Note that if an interrupt of higher priority level goes active prior to S5P2 of the machine cycle labeled C3 in Figure 20, then in accordance with the above rules it will be serviced during C5 and C6, without any instruction of the lower priority routine having been executed. 1. 2. 3. 4. 5. (Lowest) Note that the "priority within level" structure is only used to resolve simultaneous requests of the same priority level. How Interrupts Are Handled The interrupt flags are sampled at S5P2 of every machine cycle. The samples are polled during the following machine cycle (the Timer 2 interrupt cycle is different, as described in the Response Timer Section). If one of the flags was in a set condition at S5P2 of the preceding cycle, the polling S5P2 C1 S6 C2 C3 C4 C5 E INTERRUPT GOES ACTIVE INTERRUPT LATCHED INTERRUPTS ARE POLLED LONG CALL TO INTERRUPT VECTOR ADDRESS INTERRUPT ROUTINE Figure 20. Interrupt Response Timing Diagram 30 Integrated Silicon Solution, Inc. — 1-800-379-4774 MC013-1C 11/21/98 IS89C52 Thus, the processor acknowledges an interrupt request by executing a hardware-generated LCALL to the appropriate servicing routine. In some cases it also clears the flag that generated the interrupt, and in other cases it does not. It never clears the Serial Port or Timer 2 flags. This must be done in the user's software. The processor clears an external interrupt flag (IE0 or IE1) only if it was transitionactivated. The hardware-generated LCALL pushes the contents of the Program Counter onto the stack (but it does not save the PSW) and reloads the PC with an address that depends on the source of the interrupt being serviced, as shown in the following table. Interrupt Source Interrupt Request Bits IE0 TF0 IE1 TF1 RI, TI TF2, EXF2 RST Cleared by Hardware No (level) Yes (trans.) Yes No (level) Yes (trans.) Yes No No Vector Address 0003H 000BH 0013H 001BH 0023H 002BH 0000H ISSI 1. The current instruction completes operation. 2. The PC is saved on the stack. 3. The current interrupt status is saved internally. ® When an interrupt is accepted, the following action occurs: 4. Interrupts are blocked at the level of the interrupts. 5. The PC is loaded with the vector address of the ISR (interrupts service routine). 6. The ISR executes. The ISR executes and takes action in response to the interrupt. The ISR finishes with RETI (return from interrupt) instruction. This retrieves the old value of the PC from the stack and restores the old interrupt status. Execution of the main program continues where it left off. INT0 Timer 0 INT1 Timer 1 Serial Port Timer 2 System Reset External Interrupts The external sources can be programmed to be levelactivated or transition-activated by setting or clearing bit IT1 or IT0 in Register TCON. If ITx= 0, external interrupt x is triggered by a detected low at the INTx pin. If ITx = 1, external interrupt x is edge-triggered. In this mode if successive samples of the INTx pin show a high in one cycle and a low in the next cycle, interrupt request flag IEx in TCON is set. Flag bit IEx then requests the interrupt. Since the external interrupt pins are sampled once each machine cycle, an input high or low should hold for at least 12 oscillator periods to ensure sampling. If the external interrupt is transition-activated, the external source has to hold the request pin high for at least one machine cycle, and then hold it low for at least one machine cycle to ensure that the transition is seen so that interrupt request flag IEx will be set. IEx will be automatically cleared by the CPU when the service routine is called. If the external interrupt is level-activated, the external source has to hold the request active until the requested interrupt is actually generated. Then the external source must deactivate the request before the interrupt service routine is completed, or else another interrupt will be generated. Execution proceeds from that location until the RETI instruction is encountered. The RETI instruction informs the processor that this interrupt routine is no longer in progress, then pops the top two bytes from the stack and reloads the Program Counter. Execution of the interrupted program continues from where it left off. Note that a simple RET instruction would also have returned execution to the interrupted program, but it would have left the interrupt control system thinking an interrupt was still in progress. SFR Register and Bit Position TCON.1 TCON.3 TCON.7 TCON.5 SCON.1 SCON.0 T2CON.7 T2CON.6 Interrupt External 0 External 1 Timer 1 Timer 0 Serial Port Serial Port Timer 2 Timer 2 Flag IE0 IE1 TF1 TF0 TI RI TF2 EXF2 Integrated Silicon Solution, Inc. — 1-800-379-4774 MC013-1C 11/21/98 31 IS89C52 Response Time The INT0 and INT1 levels are inverted and latched into the interrupt flags IE0 and IE1 at S5P2 of every machine cycle. Similarly, the Timer 2 flag EXF2 and the Serial Port flags RI and TI are set at S5P2. The values are not actually polled by the circuitry until the next machine cycle. 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. If a request is active and conditions are right for it to be acknowledged, a hardware subroutine call to the requested service routine will be the next instruction executed. The call itself takes two cycles. Thus, a minimum of three complete machine cycles elapsed between activation of an external interrupt request and the beginning of execution of the first instruction of the service routine. Figure 19 shows response timings. A longer response time results if the request is blocked by one of the three previously listed conditions. If an interrupt of equal or higher priority level is already in progress, the additional wait time depends on the nature of the other interrupt's service routine. If the instruction in progress is not in its final cycle, the additional wait time cannot be more than three cycles, since the longest instructions (MUL and DIV) are only four cycles long. If the instruction in progress is RETI or an access to IE or IP, the additional wait time cannot be more than five cycles (a maximum of one more cycle to complete the instruction in progress, plus four cycles to complete the next instruction if the instruction is MUL or DIV). Thus, in a single-interrupt system, the response time is always more than three cycles and less than nine cycles. ISSI Single-Step Operation ® The IS89C52 interrupt structure allows single-step execution with very little software overhead. As previously noted, an interrupt request will not be serviced while an interrupt of equal priority level is still in progress, nor will it be serviced after RETI until at least one other instruction has been executed. Thus, once an interrupt routine has been entered, it cannot be re-entered until at least one instruction of the interrupted program is executed. One way to use this feature for single-step operation is to program one of the external interrupts (for example, INT0) to be level-activated. The service routine for the interrupt will terminate with the following code: JNB JB RETI P3.2,$ P3.2,$ ;Wait Here Till INT0 Goes High ;Now Wait Here Till it Goes Low ;Go Back and Execute One Instruction If the INT0 pin, which is also the P3.2 pin, is held normally low, the CPU will go right into the External Interrupt 0 routine and stay there until INT0 is pulsed (from low-tohigh-to-low). Then it will execute RETI, go back to the task program, execute one instruction, and immediately reenter the External Interrupt 0 routine to await the next pulsing of P3.2. One step of the task program is executed each time P3.2 is pulsed. 32 Integrated Silicon Solution, Inc. — 1-800-379-4774 MC013-1C 11/21/98 IS89C52 OTHER INFORMATION Reset The reset input is the RST pin, which is the input to a Schmitt Trigger. A reset is accomplished by holding the RST pin high for at least two machine cycles (24 oscillator periods), while the oscillator is running. The CPU responds by generating an internal reset, with the timing shown in Figure 21. The external reset signal is asynchronous to the internal clock. The RST pin is sampled during State 5 Phase 2 of every machine cycle. The port pins will maintain their current activities for 19 oscillator periods after a logic 1 has been sampled at the RST pin; that is, for 19 to 31 oscillator periods after the external reset signal has been applied to the RST pin. The internal reset algorithm writes 0s to all the SFRs except the port latches, the Stack Pointer, and SBUF. The port latches are initialized to FFH, the Stack Pointer to 07H, and SBUF is indeterminate. Table 9 lists the SFRs and their reset values. Then internal RAM is not affected by reset. On power-up the RAM content is indeterminate. Table 11. Reset Values of the SFR's SFR Name PC ACC B PSW SP DPTR P0-P3 IP IE TMOD TCON T2CON TH0 TL0 TH1 TL1 TH2 TL2 RCAP2H RCAP2L SCON SBUF PCON Reset Value 0000H 00H 00H 00H 07H 0000H FFH XX000000B 0X000000B 00H 00H 00H 00H 00H 00H 00H 00H 00H 00H 00H 00H Indeterminate 0XXX0000B ISSI ® 12 OSC. PERIODS S5 S6 S1 S2 S3 S4 S5 S6 S1 S2 S3 S4 S5 S6 S1 S2 S3 S4 RST SAMPLE RST SAMPLE RST INTERNAL RESET SIGNAL ALE PSEN P0 INST ADDR INST ADDR INST ADDR INST ADDR INST ADDR 11 OSC. PERIODS 19 OSC. PERIODS Figure 21. Reset Timing Integrated Silicon Solution, Inc. — 1-800-379-4774 MC013-1C 11/21/98 33 IS89C52 Power-on Reset For the IS89C52, the external resistor can be removed because the RST pin has an internal pulldown. The capacitor value can then be reduced to 1 µF (see Figure 22). When power is turned on, the circuit holds the RST pin high for an amount of time that depends on the value of the capacitor and the rate at which it charges. To ensure a good reset, the RST pin must be high long enough to allow the oscillator time to start-up (normally a few msec) plus two machine cycles. Vcc ISSI ® 1.0 µF + IS89C52 RST Vcc Note that the port pins will be in a random state until the oscillator has start and the internal reset algorithm has written 1s to them. With this circuit, reducing VCC quickly to 0 causes the RST pin voltage to momentarily fall below 0V. However, this voltage is internally limited and will not harm the device. GND Figure 22. Power-On Reset Circuit 34 Integrated Silicon Solution, Inc. — 1-800-379-4774 MC013-1C 11/21/98 IS89C52 Power-Saving Modes of Operation The IS89C52 has two power-reducing modes. Idle and Power-down. The input through which backup power is supplied during these operations is Vcc. Figure 23 shows the internal circuitry which implements these features. In the Idle mode (IDL = 1), the oscillator continues to run and the Interrupt, Serial Port, and Timer blocks continue to be clocked, but the clock signal is gated off to the CPU. In Power-down (PD = 1), the oscillator is frozen. The Idle and Power-down modes are activated by setting bits in Special Function Register PCON. ISSI ® XTAL 2 OSC XTAL 1 INTERRUPT, SERIAL PORT, TIMER BLOCKS CPU CLOCK GEN PD IDL Idle Mode An instruction that sets PCON.0 is the last instruction executed before the Idle mode begins. In the Idle mode, the internal clock signal is gated off to the CPU, but not to the Interrupt, Timer, and Serial Port functions. The CPU status is preserved in its entirety; the Stack Pointer, Program Counter, Program Status Word, Accumulator, and all other registers maintain their data during Idle. The port pins hold the logical states they had at the time Idle was activated. ALE and PSEN hold at logic high levels. There are two ways to terminate the Idle. Activation of any enabled interrupt will cause PCON.0 to be cleared by hardware, terminating the Idle mode. The interrupt will be serviced, and following RETI the next instruction to be executed will be the one following the instruction that put the device into Idle. The flag bits GF0 and GF1 can be used to indicate whether an interrupt occurred during normal operation or during an Idle. For example, an instruction that activates Idle can also set one or both flag bits. When Idle is terminated by an interrupt, the interrupt service routine can examine the flag bits. The other way of terminating the Idle mode is with a hardware reset. Since the clock oscillator is still running, the hardware reset must be held active for only two machine cycles (24 oscillator periods) to complete the reset. The signal at the RST pin clears the IDL bit directly and asynchronously. At this time, the CPU resumes program execution from where it left off; that is, at the instruction following the one that invoked the Idle Mode. As shown in Figure 22, two or three machine cycles of program execution may take place before the internal reset algorithm takes control. On-chip hardware inhibits access to the internal RAM during his time, but access to the port pins is not inhibited. To eliminate the possibility of unexpected outputs at the port pins, the instruction following the one that invokes Idle should not write to a port pin or to external data RAM. Figure 23. Idle and Power-Down Hardware Power-down Mode An instruction that sets PCON.1 is the last instruction executed before Power-down mode begins. In the Powerdown mode, the on-chip oscillator stops. With the clock frozen, all functions are stopped, but the on-chip RAM and Special function Registers are held. The port pins output the values held by their respective SFRs. ALE and PSEN output lows. In the Power-down mode of operation, Vcc can be reduced to as low as 2V. However, Vcc must not be reduced before the Power-down mode is invoked, and Vcc must be restored to its normal operating level before the Power-down mode is terminated. The reset that terminates Power-down also frees the oscillator. 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 (normally less than 10 msec). The only exit from Power-down is a hardware reset. Reset redefines all the SFRs but does not change the on-chip RAM. Integrated Silicon Solution, Inc. — 1-800-379-4774 MC013-1C 11/21/98 35 IS89C52 Table 12. Status of the External Pins During Idle and Power-down Modes. Mode Idle Idle Power-down Power-down Memory Internal External Internal External ALE 1 1 0 0 ISSI PSEN 1 1 0 0 PORT 0 Data Float Data Float PORT 1 Data Data Data Data PORT 2 Data Address Data Data PORT 3 Data Data Data Data ® On-Chip Oscillators The on-chip oscillator circuitry of the IS89C52 is a single stage inverter, intended for use as a crystal-controlled, positive reactance oscillator. In this application the crystal is operated in its fundamental response mode as an inductive reactance in parallel resonance with capacitance external to the crystal (Figure 24). Examples of how to drive the clock with external oscillator are shown in Figure 25. The crystal specifications and capacitance values (C1 and C2 in Figure 24) are not critical. 20 pF to 30 pF can be used in these positions at a 12 MHz to 24 MHz frequency with good quality crystals. (For ranges greater than 24 MHz refer to Figure 26.) A ceramic resonator can be used in place of the crystal in cost-sensitive applications. When a ceramic resonator is used, C1 and C2 are normally selected to be of somewhat higher values. The manufacturer of the ceramic resonator should be consulted for recommendation on the values of these capacitors. C2 XTAL2 NC XTAL2 C1 XTAL1 EXTERNAL OSCILLATOR SIGNAL XTAL1 GND GND Figure 21. Oscillator Connections Figure 22. External Clock Drive Configuration 36 Integrated Silicon Solution, Inc. — 1-800-379-4774 MC013-1C 11/21/98 IS89C52 ISSI ® XTAL2 XTAL1 R C2 C1 Figure 26. Oscillator Connections for High Speed (> 24 MHz) Note: When the frequency is higher than 24 MHz, please refer to Table 11 for recommended values of C1, C2, and R. Table 13. Recommended Value for C1, C2, R Frequency Range 3.5 MHz - 24 MHz 30 MHz - 40 MHz 20 pF-30 pF 3 pF-10 pF 20 pF-30 pF 3 pF-10 pF Not Apply 6.2K-10K C1 C2 R Integrated Silicon Solution, Inc. — 1-800-379-4774 MC013-1C 11/21/98 37 IS89C52 Program Memory Lock System The program lock system, when programmed, protects the code against software piracy. The IS89C52 has a three-level program lock system (see Table 14). The lockbits are programmed in the same manner as the program memory. The detailed lock-bits features are listed in Table 14. ISSI ® Table 14. Program Lock Bits 1 2 LB1 U P LB2 U U LB3 U U Protection Type No Program Lock Features enabled. MOVC instructions executed from external program memory are diabled form fetching code bytes from internal memory, EA is sampled and latched on Reset and further programming of the Flash is disabled. Same as 2, also verify is disabled. Same as 3, also external execution is disabled. 3 4 P P P P U P FLASH MEMORY Programming the IS89C52 The IS89C52 is normally shipped with the on-chip Flash memory array in the erased state (i.e., contents = FFH) and ready to be programmed. The IS89C52 is programmed byte-by-byte in programming mode. Before the on-chip flash code memory can be re-programmed, the entire memory array must be erased electrically. Programming Interface Every code byte in the Flash array can be written and the entire array can be erased using the appropriate combination of control signals. The write operation cycles is self-timed once initiated, will automatically time itself to completion. The programming interface is shown in Table 15 and Figures 27 and 28. Table 15. Flash Programming Mode Mode Program Code Data Verify Code Data Program Lock Bit 1 Program Lock Bit 2 Program Lock Bit 3 Read Signature Byte Chip Erase RST H H H H H H H PSEN L L L L L L L ALE/PROG H EA/VPP 12V H 12V 12V 12V P2.6 L L H H H L H P2.7 H L H H L L L P3.6 H H H L H L L P3.7 H H H L L L L H H 12V 38 Integrated Silicon Solution, Inc. — 1-800-379-4774 MC013-1C 11/21/98 IS89C52 ISSI IS89LV52 + 5V ® A0-A7 P1 Vcc P0 PGM DATA A11-A8 P2.0-P2.3 P2.6 CONTROL SIGNALS P2.7 P3.6 P3.7 ALE PROG EA VPP XTAL2 RST 3.5-12 MHz XTAL1 GND PSEN VIH Figure 27. Programming the Flash Memory IS89LV52 + 5V A0-A7 P1 Vcc P0 PGM DATA (USE 10K PULLUPS) A12-A8 P2.0-P2.4 P2.6 CONTROL SIGNALS P2.7 P3.6 P3.7 ALE VIH EA XTAL2 RST 3.5-12 MHz XTAL1 GND PSEN VIH Figure 28. Verifying the Flash Memory Integrated Silicon Solution, Inc. — 1-800-379-4774 MC013-1C 11/21/98 39 IS89C52 Programming Algorithm Before programming the IS89C52, the control signals, the address, data should be setup according to the programming mode table and programming interface. To program the IS89C52, the following sequence should be followed: 1. Insert the desired memory location on the address bus. 2. Insert the appropriate data byte on the data bus. 3. Active the correct combination of control signals. 4. Raise EA / VPP to 12V. 5. Pulse ALE / PROG once to program a byte in the Flash array, Encryption array or the lock bits. 6. Set EA / VPP to 5 V and verify data. If the data is correct then execute step 7, otherwise execute steps 1-6. 7. Repeat steps 1 through 6, changing the address and data for the entire array or until the end of the object file is reached. ISSI Erasing Chip ® All Flash memory cells must be programmed to '00' (include encryption array and lock bits) before the chip is erased. The entire Flash array is erased electrically by using the proper combination of control signals and by holding ALE/ PROG low for tGLGHE duration (See Table 16. Flash Programming and Verification Characteristics for tGLGHE value.) After the chip is erased, the code array and lock bits are written with all “1”s. If any Flash memory cell is not '1' (including lock bits), repeat the chip erase again. The chip erase operation must be executed successfully before the code memory can be re-programmed. Reading the Signature Bytes The signature bytes are read by the same procedure as a normal verification of locations 030H, 031H and 032H, except that P3.6 and P3.7 need to be pulled to a logic low. The values returned are: Signature Location (030H) (031H) (032H) Program Verify If lock bits LB1, LB2 and LB3 have not been programmed, the programmed code data can be read back via the address and data lines for verification. The lock bits cannot be verified directly. Verification of lock bits is achieved by observing that their features are enabled. To verify the data after all addresses are programmed completely, power down the IS89C52 and then reapply power. The programmed data can then be verified by applying the verify signals to the device. Value D5H indicates manufactured by ISSI 51H indicates IS89C52 FFH indicates programming voltage is 12V 40 Integrated Silicon Solution, Inc. — 1-800-379-4774 MC013-1C 11/21/98 IS89C52 ISSI ® FLASH PROGRAMMING AND VERIFICATION CHARACTERISTICS AND WAVEFORMS Table 16. Flash Programming and Verification Characteristics(1) Symbol VPP 1/tCLCL tAVGL tGHAX tDVGL tGHDX tEHSH tSHGL tGHSL tGLGH tGHGL tAVQV tELQV tEHQZ tGLGHE tELPL tPLPH tPHEH tEHVH Parameter Programming Supply Voltage Oscillator Frequency Address Setup to PROG Low Address Hold after PROG Data Setup to PROG Low Data Hold after PROG COND ENABLE to VPPH VPPH Setup to PROG Low VPPH Hold after PROG PROG Pulse Width PROG High to PROG Low Address to Data Valid COND ENABLE to Data Valid Data Float after COND DISABLE Erase PROG Pulse Width COND DISABLE to Power Low Power Off Time Power On to VPPL VPPL to COND ENABLE Min 11.5 3.5 48 48 48 48 48 10 10 120 10 — — — 200 0 10 10 0 Max 12.5 12 — — — — — — — — — 48 48 48 — — — — — Unit V MHz tCLCL tCLCL tCLCL tCLCL tCLCL µs µs µs µs tCLCL tCLCL tCLCL ms ns µs ms ns Notes: 1. TA = 21°C to 27°C, Vcc = 5.0V ± 10%. 2. COND ENABLE and COND DISABLE are generated and depend on the control signals on pins P2.6, P2.7, P3.6 and P3.7. The signals set the device in to and out of different processing conditions, such as programming condition, erasing condition, and verify condition. Integrated Silicon Solution, Inc. — 1-800-379-4774 MC013-1C 11/21/98 41 IS89C52 ISSI ADDRESS ADDRESS ® P2.3-P2.0 P1.7-P1.0 tAVGL tGHAX DATAIN tAVQV DATAOUT P0.7-P0.0 tDVGL tGHDX VPPH VPPL EA/VPP tSHGL tGLGH tGHSL 25 PULSE (1) 0V ALE/PROG tEHSH tGHGL tELQV PROGRAMMING COND. VERIFY COND.(2) tELQZ DON'T CARE P2.6, P2.7 P3.6, P3.7 DON'T CARE Figure 29. Flash Memory Programming and Verification Timing Waveform Notes: 1. One pulse for the main code array, 25 pulses for the encryption array and lock bits. 2. This verify condition is using at main code verification. 3. Power off waveform not shown. Vcc P2.3-P2.0 P1.7-P1.0 P0.7-P0.0 VPPH 0V tPLPH tELPL 0V ADDRESS tAVQV 0V DATAOUT tPHEH 0V VPPL 0V EA/VPP tGHSL tSHGL ALE/PROG tGLGHE tEHSH 0V tELQV tEHQZ tEHVH 0V VERIFY COND. DON'T CARE P2.6, P2.7 P3.6, P3.7 DON'T CARE ERASE COND. Figure 30. Flash Memory Erase Timing Waveform Note: 1. The power off and power on waveform can be used in programming or erasing. 42 Integrated Silicon Solution, Inc. — 1-800-379-4774 MC013-1C 11/21/98 IS89C52 ABSOLUTE MAXIMUM RATINGS(1) Symbol VTERM TBIAS TSTG PT Parameter Terminal Voltage with Respect to GND(2) Temperature Under Bias(3) Storage Temperature Power Dissipation Value –2.0 to +7.0 –40 to +85 –65 to +125 1.5 Unit V °C °C W ISSI ® Note: 1. Stress greater than 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 above those indicated in the operational sections of this specification is not implied. Exposure to absolute maximum rating conditions for extended periods may affect reliability. 2. Minimum DC input voltage is –0.5V. During transitions, inputs may undershoot to – 2.0V for periods less than 20 ns. Maximum DC voltage on output pins is Vcc + 0.5V which may overshoot to Vcc + 2.0V for periods less than 20 ns. 3. Operating temperature is for commercial products only defined by this specification. OPERATING RANGE(1) Range Commercial Industrial Ambient Temperature 0°C to +70°C –40°C to +85°C VCC 5V ± 10% 5V ± 10% Oscillator Frequency 3.5 to 40 MHz 3.5 to 40 MHz Note: 1. Operating ranges define those limits between which the functionality of the device is guaranteed. Integrated Silicon Solution, Inc. — 1-800-379-4774 MC013-1C 11/21/98 43 IS89C52 DC CHARACTERISTICS (Over Operating Range; GND = 0V) Symbol VIL VIL1 VIH VIH1 VSCH+ VSCH– VOL(1) Parameter Input low voltage (All except EA) Input low voltage (EA) Input high voltage (All except XTAL 1, RST) Input high voltage (XTAL 1) RST positive schmitt-trigger threshold voltage RST negative schmitt-trigger threshold voltage Output low voltage (Ports 1, 2, 3) VOL1 (1) ISSI Test conditions Min –0.5 –0.5 0.2Vcc + 0.9 0.7Vcc 0.7Vcc 0 Iol = 100 µA IOL = 1.6 mA IOL = 3.5 mA Output low voltage (Port 0, ALE, PSEN) IOL = 200 µA IOL = 3.2 mA IOL = 7.0 mA IOH = –10 µA Vcc = 4.5V-5.5V IOL = –25 µA IOL = –60 µA — — — — — — 0.9Vcc 0.75Vcc 2.4 0.9Vcc 0.75Vcc 2.4 — –10 — 50 Max 0.2Vcc – 0.1 0.2Vcc – 0.3 Vcc + 0.5 Vcc + 0.5 Vcc + 0.5 0.2Vcc 0.3 0.45 1.0 0.3 0.45 1.0 — — — — — — –80 +10 –650 300 Unit V V V V V V V V V V V V V V V V V V µA µA µA KΩ ® VOH Output high voltage (Ports 1, 2, 3, ALE, PSEN) VOH1 Output high voltage (Port 0, ALE, PSEN) IOH = –80 µA Vcc = 4.5V-5.5V IOH = –300 µA IOH = –800 µA IIL ILI ITL RRST Note: Logical 0 input current (Ports 1, 2, 3) VIN = 0.45V Input leakage current (Port 0) Logical 1-to-0 transition current (Ports 1, 2, 3) RST pulldown resister 0.45V < VIN < Vcc VIN = 2.0V 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 greater than the listed test conditions. 44 Integrated Silicon Solution, Inc. — 1-800-379-4774 MC013-1C 11/21/98 IS89C52 POWER SUPPLY CHARACTERISTICS Symbol Icc Parameter Power supply current Active mode (1) ISSI Test conditions Vcc = 5.0V 12 MHz 16 MHz 20 MHz 24 MHz 32 MHz 40 MHz Idle mode 12 MHz 16 MHz 20 MHz 24 MHz 32 MHz 40 MHz Power-down mode VCC = 5V — — — — — — — — — — — — — 20 26 32 38 50 62 5 6 7.6 9 12 15 50 mA mA mA mA mA mA mA mA mA mA mA mA µA Min Max Unit ® Note: 1. See Figures 31, 32, 33, and 34 for Icc test conditiions. Vcc Vcc RST Vcc Vcc P0 Icc Vcc Icc RST Vcc Vcc P0 NC CLOCK SIGNAL XTAL2 XTAL1 GND NC EA XTAL2 XTAL1 GND CLOCK SIGNAL EA Figure 31. Active Mode Vcc Icc RST Vcc Vcc P0 Figure 32. Idle Mode NC XTAL2 XTAL1 GND EA Figure 33. Power-down Mode Integrated Silicon Solution, Inc. — 1-800-379-4774 MC013-1C 11/21/98 45 IS89C52 tCLCX Vcc – 0.5V 0.45V 0.7Vcc 0.2Vcc – 0.1 ISSI tCHCX ® tCHCL tCLCL Figure 34. Icc Test Conditions tCLCH Note: 1. Clock signal waveform for Icc tests in active and idle mode (tCLCH = tCHCL = 5 ns) AC CHARACTERISTICS (Over Operating Range; GND = 0V; CL for Port 0, ALE and PSEN Outputs = 100 pF; CL for Other Outputs = 80 pF) EXTERNAL MEMORY CHARACTERISTICS 24 MHz Clock Min Max — — 68 — 26 — 31 — — 147 31 — 110 — — 105 0 — — 37 — 188 — 10 230 — 230 — — 157 0 — — 78 — 282 — 323 105 145 146 — 26 — 31 — — 0 26 57 40 MHz Clock Min Max —— 35 — 10 — 15 — — 80 15 — 60 — — 55 0 — — 20 — 105 — 10 130 — 130 — — 90 0 — — 45 — 165 — 190 55 95 80 — 10 — 15 — — 0 10 40 Variable Oscillator (3.5 - 40 MHz) Min Max 3.5 40 2tCLCL–15 — tCLCL–15 — tCLCL–10 — — 4tCLCL–20 tCLCL–10 — 3tCLCL–15 — — 3tCLCL–20 0 — — tCLCL–5 — 5tCLCL–20 — 10 6tCLCL–20 — 6tCLCL–20 — — 4tCLCL–10 0 — — 2tCLCL–5 — 7tCLCL–10 — 8tCLCL–10 3tCLCL–20 3tCLCL+20 4tCLCL–20 — tCLCL–15 — tCLCL–10 — — 0 tCLCL–15 tCLCL+15 Symbol 1/tCLCL tLHLL tAVLL tLLAX tLLIV tLLPL tPLPH tPLIV tPXIX tPXIZ tAVIV tPLAZ tRLRH tWLWH tRLDV tRHDX tRHDZ tLLDV tAVDV tLLWL tAVWL tQVWX tWHQX tRLAZ tWHLH Parameter Oscillator frequency ALE pulse width Address valid to ALE low Address hold after ALE low ALE low to valid instr in ALE low to PSEN low PSEN pulse width PSEN low to valid instr in Input instr hold after PSEN Input instr float after PSEN Address to valid instr in PSEN low to address float RD pulse width WR pulse width RD low to valid data in Data hold after RD Data float after RD ALE low to valid data in Address to valid data in ALE low to RD or WR low Address to RD or WR low Data valid to WR transition Data hold after WR RD low to address float RD or WR high to ALE high Unit MHz ns ns ns ns ns ns ns ns ns ns ns ns ns ns ns ns ns ns ns ns ns ns ns ns 46 Integrated Silicon Solution, Inc. — 1-800-379-4774 MC013-1C 11/21/98 IS89C52 SERIAL PORT TIMING: SHIFT REGISTER MODE 24 MHz Clock Min Max 490 510 406 — 73 0 — — — 417 40 MHz Clock Min Max 290 310 240 — 40 0 — — — 250 ISSI Variable Oscillator (3.5-40 MHz) Min Max 12tCLCL–10 12tCLCL+10 10tCLCL–10 — 2tCLCL–10 0 — — — 10tCLCL ® Symbol tXLXL tQVXH tXHQX tXHDX tXHDV Parameter Serial port clock cycle time Output data setup to clock rising edge Output data hold after clock rising edge Input data hold after clock rising edge Clock rising edge to input data valid Unit ns ns ns ns ns EXTERNAL CLOCK DRIVE CHARACTERISTICS Symbol 1/tCLCL tCHCX tCLCX tCLCH tCHCL Parameter Oscillator Frequency High time Low time Rise time Fall time Min 3.5 10 10 — — Max 40 — — 10 10 Unit MHz ns ns ns ns Integrated Silicon Solution, Inc. — 1-800-379-4774 MC013-1C 11/21/98 47 IS89C52 ISSI ® TIMING WAVEFORMS tLHLL ALE tLLPL tAVLL tPLPH tPLIV tPLAZ tPXIZ A7-A0 PSEN tLLAX tPXIX INSTR IN PORT 0 A7-A0 tLLIV tAVIV PORT 2 A15-A8 A15-A8 Figure 35. External Program Memory Read Cycle ALE tWHLH PSEN tLLDV tLLWL tRLRH tRHDZ tRHDX DATA IN A7-A0 FROM PCL INSTR IN RD PORT 0 tAVLL tRLAZ tLLAX tRLDV A7-A0 FROM RI OR DPL tAVWL tAVDV PORT 2 A15-A8 FROM DPH A15-A8 FROM PCH Figure 36. External Data Memory Read Cycle 48 Integrated Silicon Solution, Inc. — 1-800-379-4774 MC013-1C 11/21/98 IS89C52 ISSI ALE tWHLH ® PSEN tLLWL tWLWH tWHQX A7-A0 FROM PCL INSTR IN WR PORT 0 tAVLL tLLAX A7-A0 FROM RI OR DPL tQVWX DATA OUT tAVWL PORT 2 A15-A8 FROM DPH A15-A8 FROM PCH Figure 37. External Data Memory Write Cycle INSTRUCTION 0 1 2 3 4 5 6 7 8 ALE tXLXL CLOCK tQVXH tXHQX 0 tXHDV 1 2 tXHDX VALID DATAOUT DATAIN 3 4 5 6 7 SET TI VALID VALID VALID VALID VALID VALID VALID SET RI Figure 38. Shift Register Mode Timing Waveform tCLCX Vcc – 0.5V 0.45V 0.7Vcc 0.2Vcc – 0.1 tCHCX tCHCL tCLCL tCLCH Figure 39. External Clock Drive Waveform Vcc - 0.5V 0.45V 0.2Vcc + 0.9V 0.2Vcc - 0.1V Figure 40. AC Test Point Note: 1. AC inputs during testing are driven at VCC – 0.5V for logic “1” and 0.45V for logic “0”. Timing measurements are made at VIH min for logic “1” and max for logic “0”. Integrated Silicon Solution, Inc. — 1-800-379-4774 MC013-1C 11/21/98 49 IS89C52 ORDERING INFORMATION Commercial Range: 0°C to +70°C Speed 12 MHz Order Part Number IS89C52-12PL IS89C52-12W IS89C52-12PQ IS89C52-24PL IS89C52-24W IS89C52-24PQ IS89C52-40PL IS89C52-40W IS89C52-40PQ Package PLCC – Plastic Leaded Chip Carrier 600-mil Plastic DIP PQFP PLCC – Plastic Leaded Chip Carrier 600-mil Plastic DIP PQFP PLCC – Plastic Leaded Chip Carrier 600-mil Plastic DIP PQFP ISSI ® 24 MHz 40 MHz ORDERING INFORMATION Industrial Range: –40°C to +85°C Speed 12 MHz Order Part Number IS89C52-12PLI IS89C52-12WI IS89C52-12PQI IS89C52-24PLI IS89C52-24WI IS89C52-24PQI IS89C52-40PLI IS89C52-40WI IS89C52-40PQI Package PLCC – Plastic Leaded Chip Carrier 600-mil Plastic DIP PQFP PLCC – Plastic Leaded Chip Carrier 600-mil Plastic DIP PQFP PLCC – Plastic Leaded Chip Carrier 600-mil Plastic DIP PQFP 24 MHz 40 MHz ISSI ® Integrated Silicon Solution, Inc. 2231 Lawson Lane Santa Clara, CA 95054 Fax: (408) 588-0806 Toll Free: 1-800-379-4774 http://www.issi.com 50 Integrated Silicon Solution, Inc. — 1-800-379-4774 MC013-1C 11/21/98