Synchronous Operation - Renesas F-ZTAT H8 Series Hardware Manual

Section 13 Serial Communication Interface
• 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
Start receiving
Read ORER flag in SSR
ORER = 1?
Read RDRF flag in SSR
No
RDRF = 1?
Read receive data
from RDR, and clear
RDRF flag to 0 in SSR
No
Finished
receiving?
Clear RE bit to 0 in SCR
End
Figure 13.18 Sample Flowchart for Serial Receiving (1)
Rev. 7.00 Sep 21, 2005 page 498 of 878
REJ09B0259-0700
1
2
Yes
3
Error handling
No
continued on next page
4
Yes
5
Yes
1. SCI initialization: the receive data function of
the RxD pin is selected automatically.
2, 3. Receive error handling: if a receive error
occurs, read the ORER flag in SSR, then after
executing the necessary error handling, clear
the ORER flag to 0. Neither transmitting nor
receiving can resume while the ORER flag
remains set to 1.
4. SCI status check and receive data read: read
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
given by the RXI interrupt.
5. To continue receiving serial data: check the
RDRF flag, read RDR, and clear the RDRF
flag to 0 before the MSB (bit 7) of the current
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.