Hitachi SH7709S Hardware Manual page 503

Receiving Serial Data (Synchronous Mode): Figure 14.21 shows a sample flowchart for
receiving serial data. When switching from asynchronous mode to synchronous mode, make sure
that ORER, PER, and FER are cleared to 0. If PER or FER is set to 1, the RDRF bit will not be set
and both transmitting and receiving will be disabled.
The procedure for receiving serial data is:
1. Receive error handling: If a receive error occurs, read the ORER bit in SCSSR to identify the
error. After executing the necessary error handling, clear ORER to 0. Transmitting/receiving
cannot resume if ORER remains set to 1.
2. SCI status check and receive data read: Read the serial status register (SCSSR), check that
RDRF is set to 1, then read receive data from the receive data register (SCRDR) and clear
RDRF to 0. The RXI interrupt can also be used to determine if the RDRF bit has changed from
0 to 1.
3. To continue receiving serial data: Read SCRDR, and clear RDRF to 0 before the MSB (bit 7)
of the current frame is received.
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