AUTOMOTIVE 80C51FA83C51FA

PIN DESCRIPTIONS

Port 0

Port 0 is an 8-bit open drain bidirectional

IO port As an output port each pin can sink several

LS TTL inputs Port 0 pins that have 1’s written to

them float and in that state can be used as high-im-

pedance 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 inter-

nal pullups when emitting1’s and can source and

sink several LS TTL inputs

Port 0 outputs the code bytes during program verifi-

cation External pullup resistors are required during

program verification

Port 1

Port 1 is an 8-bit bidirectional IO port with

internal pullups The Port 1 output buffers can drive

LS TTL inputs Port 1 pins that have 1’s written to

them are pulled high by the internal pullups and in

that state can be used as inputs As inputs Port 1

pins that are externally pulled low will source current

ups

In addition Port 1 serves the functions of the follow-

ing special features of the 83C51FA

Port Pin

Alternate Function

P10

T2 (External Count Input to Timer

Counter 2)

P11

T2EX (TimerCounter 2 Capture

Reload Trigger and Direction Control)

P12

ECI (External Count Input to the PCA)

P13

CEX0 (External IO for Compare

Capture Module 0)

P14

CEX1 (External IO for Compare

Capture Module 1)

P15

CEX2 (External IO for Compare

Capture Module 2)

P16

CEX3 (External IO for Compare

Capture Module 3)

P17

CEX4 (External IO for Compare

Capture Module 4)

Port 2

Port 2 is an 8-bit bidirectional IO port with

internal pullups The Port 2 output buffers can drive

LS TTL inputs Port 2 pins that have 1’s written to

them are pulled high by the internal pullups and in

that state can be used as inputs As inputs Port 2

pins that are externally pulled low will source current

ups

Port 2 emits the high-order address byte during

fetches from external Program Memory and during

accesses to external Data Memory that use 16-bit

addresses (MOVX

DPTR) In this application it

uses strong internal pullups when emitting 1’s Dur-

ing accesses to external Data Memory that use 8-bit

Pin (PDIP)

270501 – 3

Pad (PLCC)

270501 – 4

Do not connect reserved pins

Diagrams are for pin reference only Package sizes are not to scale

Figure 3 Pin Connections

4