SH7125_08 Datasheet, PDF (473/774 Pages) Renesas Technology Corp – Renesas 32-Bit RISC Microcomputer SuperH™ RISC engine Family

Section 12 Serial Communication Interface (SCI)
In serial reception, the SCI operates as described below.
1. The SCI monitors the transmission line, and if a 0 start bit is detected, performs internal
synchronization and starts reception.
2. The received data is stored in SCRSR in LSB-to-MSB order.
3. The parity bit and stop bit are received.
After receiving these bits, the SCI carries out the following checks.
A. Parity check: The SCI counts the number of 1s in the received data and checks whether the
count matches the even or odd parity specified by the O/E bit in the serial mode register
(SCSMR).
B. Stop bit check: The SCI checks whether the stop bit is 1. If there are two stop bits, only the
first is checked.
C. Status check: The SCI checks whether the RDRF flag is 0 and the received data can be
transferred from the receive shift register (SCRSR) to SCRDR.
If all the above checks are passed, the RDRF flag is set to 1 and the received data is stored in
SCRDR. If a receive error is detected, the SCI operates as shown in table 12.16.
Note: When a receive error occurs, subsequent reception cannot be continued. In addition,
the RDRF flag will not be set to 1 after reception; be sure to clear the error flag to 0.
4. If the EIO bit in SCSPTR is cleared to 0 and the RIE bit in SCSCR is set to 1 when the RDRF
flag changes to 1, a receive-data-full interrupt (RXI) request is generated. If the RIE bit in
SCSCR is set to 1 when the ORER, PER, or FER flag changes to 1, a receive error interrupt
(ERI) request is generated.
Table 12.16 Receive Errors and Error Conditions
Receive Error
Overrun error
Framing error
Parity error
Abbreviation
ORER
FER
PER
Error Condition
Data Transfer
When the next data reception The received data is not
is completed while the RDRF transferred from SCRSR to
flag in SCSSR is set to 1
SCRDR.
When the stop bit is 0
The received data is
transferred from SCRSR to
SCRDR.
When the received data does The received data is
not match the even or odd transferred from SCRSR to
parity specified in SCSMR SCRDR.
Rev. 4.00 Jul. 25, 2008 Page 453 of 750
REJ09B0243-0400