S3C80A5B
I/O PORTS
9-1
9
I/O PORTS
OVERVIEW
The S3C80A5B microcontroller has three bit-programmable I/O ports, P0–P2. Two ports, P0-P1, are 8-bit ports and
P2 is a 3-bit port. This gives a total of 19 I/O pins in the S3C80A5B"s 24-pin package. Each port is bit-programmable
and can be flexibly configured to meet application design requirements. The CPU accesses ports by directly writing
or reading port registers. No special I/O instructions are required.
For IR universal remote controller applications, ports 0, and1 are usually configured to the keyboard matrix and port 2
is used to transmit the remote controller carrier signal or to indicate operating status by turning on a LED.
Table 9-1 gives you a general overview of S3C80A5B I/O port functions.
Table 9-1. S3C80A5B Port Configuration Overview
Port
Configuration Options
0
8-bit general-purpose I/O port; Input or push-pull output; external interrupt input on falling edges,
rising edges, or both edges; all P0 pin circuits have noise filters and interrupt enable/disable
(P0INT) and pending control (P0PND); Pull-up resistors can be assigned to individual P0 pins
using P0PUR register settings. Specially Interrupt with Reset(INTR) is assigned to release stop
mode with system reset.
1
8-bit general-purpose I/O port; Input, open-drain output, or push-pull output. Pull-up resistors can
be assigned to individual P1 pins using P1PUR register settings.
2
3-bit I/O port; input mode with or without pull-up, push-pull or open-drain output mode. REM and
T0PWM can be assigned. Port 2 pins have high current drive capability to support LED
applications. The port 2 data register contains three status bits: three for P2.0, P2.1 and P2.2 and
one for remote controller carrier signal on/off status.