NEC PD17062 User Manual
Page 200
200
µ
PD17062
15.5.2 Example of Using Output Ports (P0C, P1A)
The output ports output the contents of the output latch from each pin.
Output data can be set by executing an instruction, such as the MOV instruction, to write the contents of
the port register for each pin.
To output a high level signal to each pin, write 1. To output a low level signal to each pin, write 0.
However, the P1A
3
, P1A
2
, P1A
1
, and P1A
0
pins, because of the N-ch open-drain output, are set to the floating
state (Hi-Z) when a high level signal is output.
Upon executing an instruction to read the port register, such as the SKT instruction, the contents of the
output latch are read.
15.5.3 State of Output Ports (P0C, P1A) at Reset
(1) At power-on reset
The contents of the output latch are output.
Since the contents of the output latch are “indefinite”, “indefinite” values are output until the output latch
is initialized by the program.
(2) At CE reset
The contents of the output latch are output.
Since the contents of the output latch are retained, the output data remains as is upon a CE reset.
(3) At clock stop
The contents of the output latch are output.
Since the contents of the output latch are retained, the output data remains as is at clock stop.
Therefore, the output latch must be initialized by the program as necessary.
(4) During halt state
The contents of the output latch are output.
Since the contents of the output latch are retained, the output data remains as is during the halt state.