Philips Semiconductors

Product specification

87C552

80C51 8-bit microcontroller

1998 May 01

5

PIN DESCRIPTION

PIN NO.

MNEMONIC

PLCC

QFP

TYPE

NAME AND FUNCTION

2

72

I

Digital Power Supply: +5V power supply pin during normal operation, idle and

power-down mode.

STADC

3

74

I

Start ADC Operation: Input starting analog to digital conversion (ADC operation can also

be started by software).

PWM0

4

75

O

Pulse Width Modulation: Output 0.

PWM1

5

76

O

Pulse Width Modulation: Output 1.

EW

6

77

I

Enable Watchdog Timer: Enable for T3 watchdog timer and disable power-down mode.

P0.0-P0.7

57-50

58-51

I/O

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 high-impedance 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 pull-ups when emitting 1s. Port 0 is also used to input

the code byte during programming and to output the code byte during verification.

P1.0-P1.7

16-23

10-17

I/O

Port 1: 8-bit I/O port. Alternate functions include:

16-21

10-15

I/O

(P1.0-P1.5): Quasi-bidirectional port pins.

22-23

16-17

I/O

(P1.6, P1.7): Open drain port pins.

16-19

10-13

I

CT0I-CT3I (P1.0-P1.3): Capture timer input signals for timer T2.

20

14

I

T2 (P1.4): T2 event input.

21

15

I

RT2 (P1.5): T2 timer reset signal. Rising edge triggered.

22

16

I/O

23

17

I/O

Port 1 is also used to input the lower order address byte during EPROM programming and

verification. A0 is on P1.0, etc.

P2.0-P2.7

39-46

38-42,

45-47

I/O

Port 2: 8-bit quasi-bidirectional I/O port.

Alternate function: High-order address byte for external memory (A08-A15). Port 2 is also

used to input the upper order address during EPROM programming and verification. A8 is

on P2.0, A9 on P2.1, through A12 on P2.4.

P3.0-P3.7

24-31

18-20,

23-27

I/O

Port 3: 8-bit quasi-bidirectional I/O port. Alternate functions include:

24

18

RxD(P3.0): Serial input port.

25

19

TxD (P3.1): Serial output port.

26

20

INT0 (P3.2): External interrupt.

27

23

INT1 (P3.3): External interrupt.

28

24

T0 (P3.4): Timer 0 external input.

29

25

T1 (P3.5): Timer 1 external input.

30

26

WR (P3.6): External data memory write strobe.

31

27

RD (P3.7): External data memory read strobe.

P4.0-P4.7

7-14

80, 1-2

4-8

I/O

Port 4: 8-bit quasi-bidirectional I/O port. Alternate functions include:

7-12

80, 1-2

4-6

O

CMSR0-CMSR5 (P4.0-P4.5): Timer T2 compare and set/reset outputs on a match with

timer T2.

13, 14

7, 8

O

CMT0, CMT1 (P4.6, P4.7): Timer T2 compare and toggle outputs on a match with timer T2.

P5.0-P5.7

68-62,

71-64,

I

Port 5: 8-bit input port.

1

ADC0-ADC7 (P5.0-P5.7): Alternate function: Eight input channels to ADC.

RST

15

9

I/O

Reset: Input to reset the 87C552. It also provides a reset pulse as output when timer T3

overflows.

XTAL1

35

32

I

Crystal Input 1: Input to the inverting amplifier that forms the oscillator, and input to the

internal clock generator. Receives the external clock signal when an external oscillator is

used.

XTAL2

34

31

O

Crystal Input 2: Output of the inverting amplifier that forms the oscillator. Left open-circuit

when an external clock is used.

36, 37

34-36

I

Digital ground.

PSEN

47

48

O

Program Store Enable: Active-low read strobe to external program memory.