UPD17P136ACT datasheet(122/292 Pages) NEC

122 / 292 page

CHAPTER 12 PORTS

103

12.3 PORT 0C (P0C0/ADC0, P0C1/ADC1, P0C2/ADC2, P0C3/ADC3)

Port 0C is a 4-bit input/output port with an output latch. It is mapped into address 72H of BANK0 in data memory.

The output format is CMOS push-pull output.

Input or output can be specified in 1-bit unit. Input/output can be specified by P0CBIO0 to P0CBIO3 (address 1CH)

in the register file.

If P0CBIOn is 0 (n = 0 to 3), the P0Cn pins are used as input port. If a data read instruction is executed for the

port register, the pin statuses are read. If P0CBIOn is 1 (n = 0 to 3), the P0Cn pins are used as output port and the

contents written in the output latch are output to pins. If a read instruction is executed when pins are used as output

ports, the contents of the latch, rather than pin statuses, are fetched.

At reset, P0CBIO0 to P0CBIO3 are 0 and all P0C pins are input ports. The contents of the port output latch are

Port 0C can also be used as an analog input to the A/D converter. P0C0IDI to P0C3IDI (1BH address) in the register

file are used to switch the port and analog input pin.

If P0CnIDI is 0 (n = 0 to 3), the P0Cn/ADCn pin functions as a port. If P0CnIDI is 1 (n = 0 to 3), the P0Cn/ADCn

pin functions as the analog input pin of the A/D converter.

ADCCH0 and ADCCH1 (bits 1 and 0 at address 22H) in the register file are used to select the input pin for A/D

conversion.

To use P0C pins as A/D converter input pins, set P0CBIOn = 0 so that they are set as input ports. (See 13.3

A/D CONVERTER.)

At reset, P0CBIO0 to P0CBIO3, P0C0IDI to P0C3IDI, ADCCH0, and ADCCH1 are set to 0 and the P0C pins are

used as input ports.

Table 12-3. Switching the Port and A/D Converter

Notes 1.

Normal setting when the pins are used as A/D converter analog input pins.

Functions as an output port. At this time, the analog input voltage changes affected by the port output.

When using this pin as an analog input pin, be sure to set P0CBIOn to 0.

(n = 0 to 3)

BANK0 72H

P0CnIDI

RF: 1BH

Pin status

P0C latch contents

Input port

Port output

A/D converter analog

inputNote1

Output port and A/D

converter analog inputNote2

P0CBIOn

RF: 1CH

Function

Possible

P0C latch

Possible

P0C latch

Possible

P0C latch

Possible

P0C latch

Write

Read

UPD17P136ACT Datasheet(PDF) 122 Page - NEC

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