Philips Semiconductors

Product specification

80C528/83C528

CMOS single-chip 8-bit microcontrollers

1995 Feb 02

7

PIN DESCRIPTION

PIN NO.

MNEMONIC

DIP

SDIL

LCC

QFP

TYPE

NAME AND FUNCTION

20

21

22

16

I

Ground: circuit ground potential.

40

42

44

38

I

Power Supply: +5V power supply pin during normal operation, Idle mode and

Power-down mode.

P0.0–0.7

39–32

41–34

43–36

37–30

I/O

Port 0: Port 0 is an 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.

P1.0–P1.7

1–8

1–8

2–9

40–44

1–3

I/O

Port 1: Port 1 is an 8-bit bidirectional I/O port with internal pull-ups, except P1.6 and

P1.7 which have open drain. Port 1 pins that have 1s written to them are pulled high

by the internal pull-ups and can be used as inputs. As inputs, port 1 pins that are

externally pulled low will source current because of the internal pull-ups. (See DC

1

1

2

40

I

T2 (P1.0): Timer/counter 2 external count input (following edge triggered).

2

2

3

41

I

T2EX (P1.1): Timer/counter 2 trigger input.

7

7

8

2

I/O

8

8

9

3

I/O

P2.0–P2.7

21–28

22–29

24–31

18–25

I/O

Port 2: Port 2 is an 8-bit bidirectional I/O port with internal pull-ups. Port 2 pins that

have 1s written to them are pulled high by the internal pull-ups and can be used as

inputs. As inputs, port 2 pins that are externally being pulled low will source current

emits the high-order address byte during fetches from external program memory

and during accesses to external data memory that use 16-bit addresses (MOVX

@DPTR). In this application, it uses strong internal pull-ups when emitting 1s.

During accesses to external data memory that use 8-bit addresses (MOV @Ri), port

2 emits the contents of the P2 special function register.

P3.0–P3.7

10–17

10–18

(11=NC)

11,

13–19

5,

7–13

I/O

Port 3: Port 3 is an 8-bit bidirectional I/O port with internal pull-ups. Port 3 pins that

have 1s written to them are pulled high by the internal pull-ups and can be used as

inputs. As inputs, port 3 pins that are externally being pulled low will source current

the special features of the SC80C51 family, as listed below:

10

10

11

5

I

RxD (P3.0): Serial input port

11

12

13

7

O

TxD (P3.1): Serial output port

12

13

14

8

I

INT0 (P3.2): External interrupt

13

14

15

9

I

INT1 (P3.3): External interrupt

14

15

16

10

I

T0 (P3.4): Timer 0 external input

15

16

17

11

I

T1 (P3.5): Timer 1 external input

16

17

18

12

O

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

17

18

19

13

O

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

RST

9

9

10

4

I/O

Reset: A high on this pin for two machine cycles while the oscillator is running,

pulled high while the internal reset signal is active.

ALE

30

31

33

27

I/O

Address Latch Enable: Output pulse for latching the low byte of the address

during an access to 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.

PSEN

29

30

32

26

O

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.

EA

31

33

35

29

I

External Access Enable: EA must be externally held low during RESET to enable

the device to fetch code from external program memory locations 0000H to 7FFFH.

If EA is held high during RESET, the device executes from internal program memory

unless the program counter contains an address greater than 7FFFH. EA is don’t

care after RESET.

XTAL1

19

20

21

15

I

Crystal 1: Input to the inverting oscillator amplifier and input to the internal clock

generator circuits.

XTAL2

18

19

20

14

O

Crystal 2: Output from the inverting oscillator amplifier.