7906 datasheet(259/531 Pages) RENESAS

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SERIAL I/O

7906 Group User’s Manual Rev.2.0

11-18

11.2 Block description

11.2.9 Port P8 direction register

I/O pins for serial I/O are multiplexed with port P1 pins. When using pins P11, P12, P15, and P16 as serial

I/O’s input pins (CTSi, RxDi), clear the corresponding bits of the port P1 direction register to “0” in order

to set these pins for the input mode. When using these pins as other serial I/O’s pins (CTSi/RTSi, CLKi,

TxDi), these pins are forcibly set as I/O pins for serial I/O regardless of the port P8 direction register’s

contents. Figure 11.2.14 shows the relationship between the port P1 direction register and serial I/O’s

I/O pins. For details, refer to the description of each operating mode.

Fig. 11.2.14 Relationship between port P1 direction register and serial I/O’s I/O pins

Corresponding pin name

Bit

Port P1 direction register (Address 516)

Function

At reset

R/W

Pin CTS0/RTS0

Pin CTS0/CLK0

Pin RxD0

Pin TxD0

Pin CTS1/RTS1

Pin CTS1/CLK1

Pin RxD1

Pin TxD1

b7 b6 b5 b4 b3 b2 b1 b0

0 : Input mode

1 : Output mode

When using pins P11, P12, P15, and P16 as serial

I/O’s input pins (CTS0, RxD0, CTS1, RxD1), clear

the corresponding bits to “0.”

7906 Datasheet(PDF) 259 Page - Renesas Technology Corp