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Rev. 5.00, 09/03, page 509 of 760
15.4.2 Retransmission (Receive and Transmit Modes)
Retransmission when SCI is in Receive Mode: Figure 15.9 shows the retransmission operation
in the SCI receive mode.
1. When the received parity bit is checked and an error is found, the PER bit in SCSSR is
automatically set to 1. If the RIE bit in SCSCR is enabled at this time, an ERI interrupt is
requested. Be sure to clear the PER bit before the next parity bit is sampled.
2. The RDRF bit in SCSSR is not set in the frame that caused the error.
3. When the received parity bit is checked and no error is found, the PER bit in SCSSR is not set.
4. When the received parity bit is checked and no error is found, reception is considered to have
been completed normally and the RDRF bit in SCSSR is automatically set to 1. If the RIE bit
in SCSCR is enabled at this time, an RXI interrupt is requested.
5. When a normal frame is received, the pin maintains a three-state state when it transmits the
error signal.
D0Ds D2D1 D4D3 D6D5 Dp DED7 D0Ds D2D1 D4D3 D6D5 Dp
(DE)
D7 D0Ds D2D1 D4D3
nth transfer frame
RDRF
PER
2
1
4
5
3
Retransmitted frame Transfer frame n + 1
Figure 15.9 Retransmission in SCI Receive Mode