SH7055S Datasheet, PDF (525/1002 Pages) Renesas Technology Corp – Renesas 32-Bit RISC Microcomputer SuperH RISC engine Family/SH7000 Series

Initialize
Clear TE and RE bits to 0 in SCR
Set CKE1 and CKE0 bits in SCR
(TE and RE bits are 0)
1
Select transmit/receive format
in SMR and SDCR
2
Set value in BRR
3
Wait
No
1-bit interval elapsed?
Yes
Set TE or RE to 1 in SCR; Set RIE,
TIE, TEIE, and MPIE as necessary ⁴
End
Figure 15.4 Sample Flowchart for SCI Initialization
Transmitting Serial Data (Asynchronous Mode): Figure 15.5 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.
Rev.2.0, 07/03, page 487 of 960