NEC PD78058F(A) Manuale Utente

142

CHAPTER 6 PORT FUNCTIONS

6.2.9 Port 7

This is a 3-bit input/output port with output latches. Input mode/output mode can be specified bit-wise by means

of port mode register 7 (PM7). When pins P70 to P72 are used as input port pins, an on-chip pull-up resistor can

be used as a 3-bit unit by means of pull-up resistor option register L (PUOL).

Alternate functions include serial interface channel 2 data input/output and clock input/output.

RESET input sets the input mode.

Figures 6-15 and 6-16 show block diagrams of port 7.

Caution When used as a serial interface pin, set the input/output and output latch according to its

functions. For the setting method, refer to Table 19-2 Serial Interface Channel 2 Operating Mode

Settings of List.

Figure 6-15. P70 Block Diagram

PUO : Pull-up resistor option register

: Port mode register

: Port 7 read signal

WR : Port 7 write signal

P-ch

PORT

PUO

Selector

PUO7

Output Latch

(P70)

PM70

Internal bus

P70/SI2/RxD