7477 datasheet(117/354 Pages) RENESAS

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HARDWARE

1-100

7470/7471/7477/7478 GROUP USER’S MANUAL

1.13 Serial I/O

[Byte specification mode setting]

For a Serial I/O transfer in the byte specification mode, refer to the setting method in the ordinary

mode in “1.13A.1 Operation description,” and also take the following into consideration.

q Select the byte specification mode. (Set bit 6 of the Serial I/O register to “1.”)

q Be sure to select the external clock as the synchronous clock. (Clear bit 2 of the Serial I/O mode

[1] When data is received, the ordinary port can be selected by the Serial I/O port selection bit

(bit 3 of the Serial I/O mode register). P16 pin is used as a external clock input pin CLK. Only

P15 is available as an ordinary port.

[2] Write data into the Serial I/O register when the synchronous clock is at “H.” However, if the

Byte counter value is a value other than “0,” writing data is enabled even if the synchronous

clock is at “L.”

q When performing a Serial I/O transmit/receive at the n–th byte, write (n – 1) in the Byte counter.

Note: Because the Byte counter is not provided with a reload function, re-set a value to transmit or

receive data continuously.

7477 Datasheet(PDF) 117 Page - Renesas Technology Corp