UPD17015GS datasheet(40/120 Pages) NEC

40 / 120 page

µPD17015

9.4.2

Using the Output Port

The output port outputs the contents of the output latch from each pin.

To set the output data, execute a write instruction (such as MOV) for the port register corresponding to each pin.

To output a high signal to a pin, write 1. To output a low signal, write 0.

Caution If a read instruction (such as SKT) is executed for a port register, the contents of the output latch

and the read data may differ because the status of the output pin is read as is.

9.4.3

Statuses of the Output Port upon Reset

(1) At power-on reset

The contents of the output latches are output.

The contents of the output latches are reset to 0.

(2) Upon CE reset

The contents of the output latch are output.

The output latch retains the data existing immediately before the reset. If a pin is directly set to output mode,

the previous contents are output.

(3) Upon a clock stop

All pins are set to input mode.

The output latch retains the last data existing immediately before the reset. If a pin is directly set to output mode,

the previous contents are output.

(4) In the halt state

The previous statuses are retained.

UPD17015GS Datasheet(PDF) 40 Page - NEC