Serial Data Reception (Except For Block Transfer Mode) - Hitachi H8S/2378, H8S/2378R Series Hardware Manual

15.7.7

Serial Data Reception (Except for Block Transfer Mode)

Data reception in Smart Card interface mode uses the same operation procedure as for normal
serial communication interface mode. Figure 15.29 illustrates the retransfer operation when the
SCI is in receive mode.
1. If an error is found when the received parity bit is checked, the PER bit in SSR is
automatically set to 1. If the RIE bit in SCR is set at this time, an ERI interrupt request is
generated. The PER bit in SSR should be cleared to 0 before the next parity bit is sampled.
2. The RDRF bit in SSR is not set for a frame in which an error has occurred.
3. If no error is found when the received parity bit is checked, the PER bit in SSR is not set to 1.
The receive operation is judged to have been completed normally, and the RDRF flag in SSR
is automatically set to 1. If the RIE bit in SCR is set at this time, an RXI interrupt request is
generated.
Figure 15.30 shows a flowchart for reception. The sequence of receive operations can be
performed automatically by specifying the DTC or DMAC to be activated with an RXI interrupt
source. In a receive operation, an RXI interrupt request is generated when the RDRF flag in SSR
is set to 1. If the RXI request is designated beforehand as a DTC or DMAC activation source, the
DTC or DMAC will be activated by the RXI request, and transfer of the receive data will be
carried out. The RDRF flag is cleared to 0 automatically when data transfer is performed by the
DTC or DMAC. If an error occurs in receive mode and the ORER or PER flag is set to 1, a
transfer error interrupt (ERI) request will be generated, and so the error flag must be cleared to 0.
In the event of an error, the DTC or DMAC is not activated and receive data is skipped.
Therefore, receive data is transferred for only the specified number of bytes in the event of an
error. Even when a parity error occurs in receive mode and the PER flag is set to 1, the data that
has been received is transferred to RDR and can be read from there.
Note: For details on receive operations in block transfer mode, refer to section 15.4, Operation in
Asynchronous Mode.
nth transfer frame
Ds D0 D1 D2 D3 D4 D5 D6 D7 Dp DE
RDRF
PER
Figure 15.29 Retransfer Operation in SCI Receive Mode
Rev. 1.0, 09/01, page 692 of 904
Retransferred frame
Ds D0 D1 D2 D3 D4 D5 D6 D7 Dp
[2]
[1]
Transfer
frame n+1
(DE)
Ds D0 D1 D2 D3 D4
[4]
[3]