1 overview – Panasonic MN101C00 User Manual

Page 52

Chapter 3 Port Functions

Overview

3-1 Overview

A total of 39 pins on the MN101C117, including those shared with special

function pins, are allocated for the 7 ports of P0 to P2, P6 to P8, and PA.

Each I/O port is assigned according to the special function register area in

memory. I/O ports are operated in byte or bit units in the same way as RAM.

• This I/O control is valid even when special functions are selected for the dual function pins.

•

Table 3-1-1 Status When Port Is Reset (single-chip mode)

For each I/O port, the PnOUT register (port n output

register) that sets the output value is assigned to memory

address X'3F1n', and the PnIN register (port n input

register) from which the input value is monitored is

assigned to memory address X'3F2n'.

Port

I/O Mode

Pull-up/Pull-down Resistor

I/O Port or Special Function

Port 0

Port 1

Port 2

Port 6

Port 7

Port 8

Port A

Input mode

No pull-up resistor

No pull-up/pull-down resistors

I/O port

■

Port 0 (P0)

4-bit CMOS tri-state I/O port.

Table 3-1-2 Port 0 Functions

P00 to P02 I/O

SBO0(TXD),

P06

SBI0(RXD),

SBT0

BUZZER

Each bit can be set individually as either an input or

output by the P0DIR register. A pull-up resistor for each

bit can be selected individually by the P0PLU register.

At reset, the input mode is selected and pull-up resistors

are disabled (high impedance output).

Pin Name

Type

Dual Function

Description