UPD6125A View Datasheet(PDF) - NEC => Renesas Technology

Part Name

Description

Manufacturer

UPD6125A

4-BIT SINGLE CHIP MICROCONTROLLER FOR REMOTE CONTROL TRANSMISSION

NEC => Renesas Technology 

µPD6125A, 6126A

11.3 I/O Pin (P3, P4 ) Note

P3/P4 are input/output pins for adding a key matrix. The LSB of control registers P13 and P14 switches between

input and output modes.

When in input mode, all pins are pulled down by the LSI to the VSS level.

When “all clear” is input or on reset, input mode goes into effect, and the output latch value becomes undefined.

Figure 11-2. I/O Pin Organization

P3/P4

Note

P13, P14

Note

P03, P04

IN/OUT I/O3

I/O2

I/O1

I/O0

IN/OUT

0 ······· Input mode

1 ······· Output mode

P3 ··· I/O00 to I/O03,

P4 ··· I/O10 to I/O13

Note µPD6125A is not equipped with P13, P14, P03, and P04.

11.4 I/O Pull-Down Resistor Organization

Input/output selection

Output signal

Input signal

VDD

P-ch

Pin

N-ch

CMOS

VSS

I/O pull-down resistor switch

(Mask option)

R Pull-down resistor

Nch

The use of pull-down resistors for I/O can be selected by using the mask option.

When the pull-down resistor switch is turned on (1 is set) by the mask option, the pull-down resistor R is turned

on only in input mode.

Caution When using the pins as key switches, turn on the pull-down resistor switch by the mask option.

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