S80L54 データシートの表示（PDF） - Intel

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S80L54

LOW VOLTAGE CHMOS SINGLE-CHIP 8-BIT MICROCONTROLLERS

Intel 

8XL52 54 58

PIN DESCRIPTIONS

VCC Supply voltage

VSS Circuit ground

Port 0 Port 0 is an 8-bit open drain bidirectional I O

port As an output port each pin can sink several

inputs Port 0 pins that have 1’s written to them float

and in that state 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 inter-

nal pullups when emitting 1’s and can source and

sink several inputs

Port 0 also receives the code bytes during OTP

ROM programming and outputs the code bytes dur-

ing program verification External pullup resistors are

required during program verification

Port 1 Port 1 is an 8-bit bidirectional I O port with

internal pullups The Port 1 output buffers can drive

several 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

(IIL on the data sheet) because of the internal pull-

ups

In addition Port 1 serves the functions of the follow-

ing special features of the 8XL5X

Port Pin

P1 0

P1 1

Alternate Function

T2 (External Count

Input to Timer

Counter 2) Clock

Out

T2EX (Timer

Counter 2 Capture

Reload Trigger and

Direction Control)

Port 1 receives the low-order address bytes during

OTP ROM programming and verifying

Port 2 Port 2 is an 8-bit bidirectional I O port with

internal pullups The Port 2 output buffers can drive

several 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

(IIL on the data sheet) because of the internal pull-

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

addresses (MOVX Ri) Port 2 emits the contents of

the P2 Special Function Register

Some Port 2 pins receive the high-order address bits

during OTP ROM programming and program verifi-

cation

Port 3 Port 3 is an 8-bit bidirectional I O port with

internal pullups The Port 3 output buffers can drive

several inputs Port 3 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 3

pins that are externally pulled low will source current

(IIL on the data sheet) because of the pullups

Port 3 also serves the functions of various special

features of the MCS-51 Family as listed below

Port Pin

Alternate Function

P3 0

P3 1

P3 2

P3 3

P3 4

P3 5

P3 6

P3 7

RXD (serial input port)

TXD (serial output port)

INT0 (external interrupt 0)

INT1 (external interrupt 1)

T0 (Timer 0 external input)

T1 (Timer 1 external input)

WR (external data memory write strobe)

RD (external data memory read strobe)

RST Reset input A high on this pin for two machine

cycles while the oscillator is running resets the de-

vice The port pins will be driven to their reset condi-

tion when a minimum VIH2 voltage is applied wheth-

er the oscillator is running or not An internal pull-

down resistor permits a power-on reset with only a

capacitor connected to VCC

4

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