SH7727 Datasheet, PDF (592/1109 Pages) Renesas Technology Corp – Renesas 32-Bit RISC Microcomputer SuperH RISC engine Family/SH7700 Series

Section 17 Serial Communication Interface (SCI)
In receiving, the SCI operates as follows:
1. The SCI monitors the communication line. When it detects a start bit (0), the SCI synchronizes
internally and starts receiving.
2. Receive data is shifted into the SCRSR in order from the LSB to the MSB.
3. The parity bit and stop bit are received. After receiving these bits, 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 the SCSMR.
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: RDRF must be 0 so that receive data can be loaded from the SCRSR into the
SCRDR.
If these checks all pass, the SCI sets RDRF to 1 and stores the received data in the SCRDR. If
one of the checks fails (receive error), the SCI operates as indicated in table 17.12.
Note: When a receive error flag is set, further receiving is disabled. The RDRF bit is not set to 1.
Be sure to clear the error flags.
4. After setting RDRF to 1, if the receive-data-full interrupt enable bit (RIE) is set to 1 in the
SCSCR, the SCI requests a receive-data-full interrupt (RXI). If one of the error flags (ORER,
PER, or FER) is set to 1 and the receive-data-full interrupt enable bit (RIE) in the SCSCR is
also set to 1, the SCI requests a receive-error interrupt (ERI).
Table 17.12 Receive Error Conditions and SCI Operation
Receive Error
Overrun error
Framing error
Parity error
Abbreviation
ORER
FER
PER
Condition
Receiving of next data ends while
RDRF is still set to 1 in SCSSR
Stop bit is 0
Parity of receive data differs from
even/odd parity setting in SCSMR
Data Transfer
Receive data not loaded
from SCRSR into SCRDR
Receive data loaded from
SCRSR into SCRDR
Receive data loaded from
SCRSR into SCRDR
Figure 17.11 shows an example of SCI receive operation in the asynchronous mode.
Rev. 5.00 Dec 12, 2005 page 520 of 1034
REJ09B0254-0500