AT89C5121 데이터 시트보기 (PDF) - Atmel Corporation

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AT89C5121

8-bit Microcontroller with Multiprotocol Smart Card Interface

Atmel Corporation 

Table 1. Ports Description (Continued)

Port

Signal

Name

Alternate

Internal

Power

Supply

ESD Type Description

A/T8xC5121

ONLY FOR PLCC52 version

P0[7:0] AD[7:0]

VCC

P2[7:0] A[15:8]

P3.6

WR

P3.7

RD

ALE

PSEN

EA

PSEN

EA

VCC

DVCC

DVCC

VCC

VCC

VCC

I/O Input/Output function Port 0

P0 is an 8-bit open-drain bi-directional I/O port. Port 0 pins that

have 1s written to them float and can be used as high impedance

inputs. To avoid any parasitic current consumption, Floating P0

inputs must be pulled to VCC or VSS.

I/O Address/Data low

Mutiplexed Address/Data LSB for external access

I/O Input/Output function Port 2

P2 is an 8-bit open-drain bi-directional I/O port with internal pull-ups

O Address high

Address Bus MSB for external access

O Write signal

Write signal asserted during external data memory write operation

I Read signal

Read signal asserted during external data memory read operation

O Address latch enable output

The falling edge of ALE strobes the address into external latch

O Program strobe enable

I External access enable

This pin must be held low to force the device to fetch code from

external program memory starting at address 0000h. It is latched

during reset and cannot be dynamically changed during operation.

9

4164G–SCR–07/06

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