Figure 14.15 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 14.15 Sample Flowchart of Simultaneous Serial Transmit and Receive Operations
Rev. 3.00 Sep. 14, 2006 Page 226 of 408
REJ09B0105-0300
TDRE = 1
Yes
Yes
OER = 1
No
RDRF = 1
Overrun error
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
TDRE flag is automatically cleared to
[1]
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
TDR.
When data is written to TDR, the
TDRE flag is automatically cleared to
0. When data is read from RDR, the
RDRF flag is automatically cleared to
[2]
0.
[4] If an overrun error occurs, read the
OER flag in SSR, and after
[4]
performing the appropriate error
processing, clear the OER flag to 0.
Transmission/reception cannot be
processing
resumed if the OER flag is set to 1.
For overrun error processing, see
figure 14.14.
[3]