Philips Semiconductors

Product specification

83C752/87C752

80C51 8-bit microcontroller family

1998 May 01

5

PIN DESCRIPTION

MNEMONIC

PIN NO.

TYPE

NAME AND FUNCTION

12

I

Circuit Ground Potential.

28

I

Supply voltage during normal, idle, and power-down operation.

P0.0–P0.4

8–6

23, 24

I/O

Port 0: Port 0 is a 5-bit bidirectional port. Port 0.0–P0.2 are open drain. Port 0.0–P0.2 pins that have

1s written to them float, and in that state can be used as high-impedance inputs. P0.3–P0.4 are

The state of the pin can always be read from the port register by the program. Port 0.3 and 0.4 have

internal pull-ups that function identically to port 3. Pins that have 1s written to them are pulled high by

the internal pull-ups and can be used as inputs.

electrical characteristics listed in the tables that follow. While these differ from “standard TTL”

applications.

6

I

7

I

OE/PGM (P0.1) – Input which specifies verify mode (output enable) or the program mode.

OE/PGM = 1 output enabled (verify mode).

OE/PGM = 0 program mode.

8

I

ASEL (P0.0) – Input which indicates which bits of the EPROM address are applied to port 3.

ASEL = 0 low address byte available on port 3.

ASEL = 1 high address byte available on port 3 (only the three least significant bits are used).

P1.0–P1.7

13–17,

20–22

I/O

Port 1: Port 1 is an 8-bit bidirectional I/O port with internal pull-ups. Port 1 pins that have 1s written to

them are pulled high by the internal pull-ups and can be used as inputs. P0.3–P0.4 pins are

bidirectional I/O port pins with internal pull-ups. As inputs, port 1 pins that are externally pulled low will

serves the special function features of the SC80C51 family as listed below:

20

I

INT0 (P1.5): External interrupt.

21

I

INT1 (P1.6): External interrupt.

22

I

T0 (P1.7): Timer 0 external input.

13–17

I

ADC0 (P1.0)–ADC4 (P1.4): Port 1 also functions as the inputs to the five channel multiplexed A/D

converter. These pins can be used as outputs only if the A/D function has been disabled. These pins

can be used as inputs while the A/D converter is enabled.

Port 1 serves to output the addressed EPROM contents in the verify mode and accepts as inputs the

value to program into the selected address during the program mode.

P3.0–P3.7

5–1,

27–25

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 because of the pull-ups. (See DC Electrical

programmed (or verified). The 11-bit address is multiplexed into this port as specified by P0.0/ASEL.

RST

9

I

Reset: A high on this pin for two machine cycles while the oscillator is running resets the device. An

After the device is reset, a 10-bit serial sequence, sent LSB first, applied to RESET, places the device

or verification purposes. The RESET serial sequence must be synchronized with the X1 input.

X1

11

I

Crystal 1: Input to the inverting oscillator amplifier and input to the internal clock generator circuits. X1

also serves as the clock to strobe in a serial bit stream into RESET to place the device in the

programming state.

X2

10

O

Crystal 2: Output from the inverting oscillator amplifier.

19

I

Analog supply voltage and reference input.

18

I

Analog supply and reference ground.

NOTE:

in the range 4.5V to 5.5V.

(e.g., 2k

Ω).