Renesas H8/3067 Series User Manual page 542

Section 13 Serial Communication Interface
In receiving, the SCI operates as follows:
• The SCI monitors the communication line. When it detects a start bit (0 bit), the SCI
synchronizes internally and starts receiving.
• Receive data is stored in RSR in order from LSB to MSB.
• The parity bit and stop bit are received.
After receiving these bits, the SCI carries out the following checks:
 Parity check: The number of 1s in the receive data must match the even or odd parity
setting of in the O/E bit in SMR.
 Stop bit check: The stop bit value must be 1. If there are two stop bits, only the first is
checked.
 Status check: The RDRF flag must be 0, indicating that the receive data can be transferred
from RSR into RDR.
If these all checks 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 shown 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.
• 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 Condition
Overrun error ORER
Framing error FER
Parity error PER
Rev. 4.00 Jan 26, 2006 page 518 of 938
REJ09B0276-0400
Receiving of next data ends while
RDRF flag is still set to 1 in SSR
Stop bit is 0
Parity of received data differs from
even/odd parity setting in SMR
Data Transfer
Receive data is not transferred
from RSR to RDR
Receive data is transferred from
RSR to RDR
Receive data is transferred from
RSR to RDR