Renesas F-ZTAT H8 Series Hardware Manual page 512

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. 3.00 Mar 21, 2006 page 484 of 814
REJ09B0302-0300
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.