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SERIAL I/O

7733 Group User’s Manual

8–45

8.4 Clock asynchronous serial I/O (UART) mode

8.4.1 Transfer rate (Baud rate: transfer clock frequency)

The transfer rate is determined by BRGi (addresses 3116, 3916, and 6516).

When a value of “n” is set in BRGi (n = 0016 to FF16), the count source is divided by (n + 1) in the BRGi,

and then the BRGi’s output is further divided by 16. (In this way, the transfer clock is generated.) Accordingly,

assuming that the baud rate is B (bps), “n” is expressed by the following formula.

n =

–1

F : BRGi’s count source frequency

An internal clock or an external clock can be selected as the BRGi’s count source by specifying the

internal/external clock selection bit (bit 3 at addresses 3016, 3816, and 6416). When an internal clock is

selected, the clock selected by the BRG count source selection bits (bits 1 and 0 at addresses 3416, 3C16,

and 6816) is the BRGi’s count source. When an external clock is selected, the clock which is input to the

CLKi pin is the BRGi’s count source.

Tables 8.4.3 to 8.4.5 list examples of baud rate setting. Be sure to set the same baud rate for both

transmitter and receiver sides.

16 ! B

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