I/O Expansion Block

I/O Port

Expansion

A

B

C

D

PA[7:0] 2mA Totem pole outputs.

bit and byte addressable.

PB[3:0] 4mA Totem pole outputs. Power up to high.

PB[7:4] 4mA Open drain outputs.

bit and byte addressable

OEA# Port A output enable. Internal weak pull up.

PC[7:4] Inputs with internal weak pull up*

PC[3:0] Inputs with internal weak pull down

byte addressable only

PD[7:0] Bi-directional I/O port

byte addressable only. Power up to input mode.

. Power up to high.

* Pull-up/down resistors are typically 50K ohms.

Previous slide

Next slide

Back to first slide

View graphic version