NEC PD17062 Manual do Utilizador descarregar pdf (Página 200)

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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, P1A2, P1A1, and P1A0 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.

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NEC PD17062 Manual do Utilizador Página 200