SH7020 Datasheet, PDF (403/509 Pages) Renesas Technology Corp – SuperH™ RISC engine

Transmitting Serial Data (clocked synchronous mode): Figure 13.17 shows a sample flowchart
for transmitting serial data. The procedure for transmitting serial data is listed below.
1. SCI initialization: select the TxD pin function with 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. The RXI interrupt can also be used to determine if the RDRF bit has changed from 0 to 1.
3. To continue transmitting serial data: read the TDRE bit to check whether it is safe to write (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) to write data in TDR, the TDRE bit is checked and cleared
automatically.
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