HD6433044 Datasheet, PDF (498/867 Pages) Hitachi Semiconductor – Hitachi Single-Chip Microcomputer

Receiving Serial Data: Figure 13-18 shows a sample flowchart for receiving serial data and
indicates the procedure to follow. When switching from asynchronous mode to synchronous
mode, make sure that the ORER, PER, and FER flags are cleared to 0. If the FER or PER flag is
set to 1 the RDRF flag will not be set and both transmitting and receiving will be disabled.
Initialize
1
1. SCI initialization: the receive data function of
the RxD pin is selected automatically.
2, 3. Receive error handling: if a receive error
Start receiving
occurs, read the ORER flag in SSR, then after
executing the necessary error handling, clear
the ORER flag to 0. Neither transmitting nor
Read ORER flag in SSR
2
receiving can resume while the ORER flag
remains set to 1.
4. SCI status check and receive data read: read
ORER = 1?
No
Yes
3
Error handling
SSR, check that the RDRF flag is set to 1,
then read receive data from RDR and clear
the RDRF flag to 0. Notification that the RDRF
flag has changed from 0 to 1 can also be
continued on next page
given by the RXI interrupt.
5. To continue receiving serial data: check the
Read RDRF flag in SSR
4
RDRF flag, read RDR, and clear the RDRF
flag to 0 before the MSB (bit 7) of the current
No
RDRF = 1?
frame is received. If the DMAC is activated
by a receive-data-full interrupt request (RXI)
to read RDR, the RDRF flag is cleared
automatically.
Yes
Read receive data
from RDR, and clear
5
RDRF flag to 0 in SSR
No
Finished
receiving?
Yes
Clear RE bit to 0 in SCR
End
Figure 13-18 Sample Flowchart for Serial Receiving (1)
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