7721 datasheet(219/577 Pages) RENESAS

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SERIAL I/O

7721 Group User’s Manual

11–16

11.3 Clock synchronous serial I/O mode

Table 11.3.1 lists the performance overview in the clock synchronous serial I/O mode, and Table 11.3.2 lists

the functions of I/O pins in this mode.

Table 11.3.1 Performance overview in clock synchronous serial I/O mode

Item

Transfer data format

Transfer rate

Transmit/Receive control

When selecting internal clock

When selecting external clock

Functions

Transfer data has a length of 8 bits.

LSB first

BRGi’s output divided by 2

Maximum 5 Mbps

____

CTS function or RTS function can be selected by software.

Table 11.3.2 Functions of I/O pins in clock synchronous serial I/O mode

Functions

Serial data output

Serial data input

Transfer clock output

Transfer clock input

____

CTS input

____

RTS output

Pin name

TxDi (P83, P87)

(Note)

RxDi (P82, P86)

CLKi (P81, P85)

___

CTSi/RTSi

(P80, P84)

Method of selection

(Dummy data is output when performing only reception.)

Port P8 direction registerU1’s corresponding bit = “0”

(Can be used as an I/O port when performing only transmission.)

Internal/External clock select bitU2 = “0”

Internal/External clock select bit = “1”

____ ____

CTS/RTS select bitU3 = “0”

____ ____

CTS/RTS select bit = “1”

Port P8 direction registerU1: address 1416

Internal/External clock select bitU2: bit 3 at addresses 3016, 3816

____ ____

CTS/RTS select bitU3: bit 2 at addresses 3416, 3C16

Note: The TxDi pin outputs “H” level until transmission starts after UARTi’s operating mode is selected.

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