MPD78C14 datasheet(79/373 Pages) NEC

79 / 373 page

CHAPTER 4 PORT FUNCTIONS

4.1 Port A (PA7 to PA0)

This is an 8-bit input/output port which has input/output buffer and output latch functions (see Figure 4-1). Port

A can be set as to input or output bit-wise using the mode A register (MA). When set to input, the pins become

high-impedance.

In the

µPD78C18/78C14A/78C12A/78C11A, pull-up resistors can be incorporated bit-wise.

Figure 4-1. Port A

When the corresponding bit of the mode A register is set (1), a port A pin functions as an input port pin, and when

reset (0), as an output port pin (see Figure 4-2).

When RESET is input or the hardware STOP mode is set, all bits of the mode A register are set and port A functions

as an input port (high-impedance).

Figure 4-2. Mode A Register Format

MA7

MA6

MA5

MA4

MA3

MA2

MA1

MA0

PA7

PA6

PA5

PA4

PA3

PA2

PA1

PA0

PAn = Output port

PAn = Input port

(n = 0 – 7)

WRM

WRP

RD0

RD1

MAn

latch

Output

latch

Output

buffer

PAn

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