Renesas F-ZTAT H8 Series Hardware Manual page 500

Section 13 Serial Communication Interface
In receiving, the SCI operates as follows.
1. The SCI monitors the receive data line. When it detects a start bit, the SCI synchronizes
internally and starts receiving.
2. Receive data is stored in RSR in order from LSB to MSB.
3. The parity bit and stop bit are received.
After receiving, the SCI makes the following checks:
a. Parity check: The number of 1s in the receive data must match the even or odd parity
setting of the O/E bit in SMR.
b. Stop bit check: The stop bit value must be 1. If there are two stop bits, only the first
stop bit is checked.
c. Status check: The RDRF flag must be 0 so that receive data can be transferred from
RSR into RDR.
If these checks all pass, the RDRF flag is set to 1 and the received data is stored in RDR. If
one of the checks fails (receive error), the SCI operates as indicated in table 13.11.
Note: When a receive error occurs, further receiving is disabled. In receiving, the RDRF flag is
not set to 1. Be sure to clear the error flags to 0.
4. When the RDRF flag is set to 1, if the RIE bit is set to 1 in SCR, a receive-data-full
interrupt (RXI) is requested. If the ORER, PER, or FER flag is set to 1 and the RIE bit in
SCR is also set to 1, a receive-error interrupt (ERI) is requested.
Table 13.11 Receive Error Conditions
Receive Error Abbreviation
Overrun error ORER
Framing error FER
Parity error PER
Rev. 3.00 Mar 21, 2006 page 472 of 814
REJ09B0302-0300
Condition
Receiving of next data ends
while RDRF flag is still set
to 1 in SSR
Stop bit is 0
Parity of receive data differs
from even/odd parity setting
in SMR
Data Transfer
Receive data not transferred
from RSR to RDR
Receive data transferred from
RSR to RDR
Receive data transferred from
RSR to RDR