SH7052 datasheet(495/919 Pages) RENESAS

495 / 919 page

469

Initialization

Clear TE and RE bits to 0 in SCR

Set value in BRR

Set transmit/receive format in SMR

(TE and RE bits cleared to 0)

Select transmit/receive format

in SMR and SDCR

Set TE or RE to 1 in SCR; Set RIE,

TIE, TEIE, and MPIE as necessary

1-bit interval elapsed?

End

Wait

Yes

Figure 14.4 Sample Flowchart for SCI Initialization

Transmitting Serial Data (Asynchronous Mode): Figure 14.5 shows a sample flowchart for

transmitting serial data. The procedure is as follows (the steps correspond to the numbers in the

flowchart):

1. SCI initialization: Set the TxD pin using the PFC.

2. SCI status check and transmit data write: Read the serial status register (SSR), check that the

TDRE bit is 1, then write transmit data in the transmit data register (TDR) and clear TDRE

to 0.

3. Continue transmitting serial data: Read the TDRE bit to check whether it is safe to write (if it

reads 1); if so, write data in TDR, then clear TDRE to 0. When the DMAC is started by a

transmit-data-empty interrupt request (TXI) in order to write data in TDR, the TDRE bit is

checked and cleared automatically.

4. To output a break at the end of serial transmission, first clear the port data register (DR) to 0,

then clear the TE bit to 0 in SCR and use the PFC to establish the TxD pin as an output port.

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