Figure 14.14 Sample Flowchart Of Simultaneous Serial Transmit And Receive Operations (Clocked Synchronous Mode) - Renesas H8 Series Hardware Manual

Section 14 Serial Communication Interface 3 (SCI3)
Start transmission/reception
Read TDRE flag in SSR
No
Write transmit data to TDR
Read OER flag in SSR
Read RDRF flag in SSR
No
Read receive data in RDR
Yes
All data received?
Clear TE and RE bits in SCR to 0
Figure 14.14 Sample Flowchart of Simultaneous Serial Transmit and Receive Operations
Rev. 1.00 Aug. 28, 2006 Page 230 of 400
REJ09B0268-0100
TDRE = 1
Yes
Yes
OER = 1
Error processing
No
RDRF = 1
Yes
No
<End>
(Clocked Synchronous Mode)
[1] Read SSR and check that the TDRE
flag is set to 1, then write transmit
data to TDR.
When data is written to TDR, the
[1]
TDRE flag is automatically cleared to
0.
[2] Read SSR and check that the RDRF
flag is set to 1, then read the receive
data in RDR.
When data is read from RDR, the
RDRF flag is automatically cleared to
0.
[3] To continue serial transmission/
reception, before the MSB (bit 7) of
the current frame is received, finish
reading the RDRF flag, reading RDR.
Also, before the MSB (bit 7) of the
current frame is transmitted, read 1
from the TDRE flag to confirm that
writing is possible. Then write data to
[4]
TDR.
When data is written to TDR, the
TDRE flag is automatically cleared to
0. When data is read from RDR, the
[2]
RDRF flag is automatically cleared to
0.
[4] If an overrun error occurs, read the
OER flag in SSR, and after
performing the appropriate error
processing, clear the OER flag to 0.
Transmission/reception cannot be
resumed if the OER flag is set to 1.
For overrun error processing, see
figure 14.13.
[3]