SH7708 datasheet(403/633 Pages) RENESAS

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character units, so a 16 pulse synchronization clock is output. To receive in 1-character units,

select an external clock source.

Transmitting and Receiving Data: SCI Initialization (synchronous mode). Before transmitting,

receiving, or changing the mode or communication format, the software must clear the TE and RE

bits to 0 in the serial control register (SCSCR), then initialize the SCI. Clearing TE to 0 sets TDRE

to 1 and initializes the transmit shift register (SCTSR). Clearing RE to 0, however, does not

initialize the RDRF, PER, FER, and ORER flags and receive data register (SCRDR), which retain

their previous contents.

Figure 13.15 is a sample flowchart for initializing the SCI. The procedure for initializing the SCI

is:

1. Select the clock source in the serial control register (SCSCR). Leave RIE, TIE, TEIE, MPIE,

TE and RE cleared to 0.

2. Select the communication format in the serial mode register (SCSMR).

3. Write the value corresponding to the bit rate in the bit rate register (SCBRR) unless an external

clock is used.

4. Wait for at least the interval required to transmit or receive one bit, then set TE or RE in the

serial control register (SCSCR) to 1. Also set RIE, TIE, TEIE and MPIE. Setting TE and RE

allows use of the TxD and RxD pins.

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