Section 12 Serial Communication Interface (SCI)
Rev. 3.00 Sep. 27, 2007 Page 462 of 758
REJ09B0243-0300
Yes
No
Start of transmission and reception
Error processing
No
Yes
ORER = 1?
All data received?
Read TDRE flag in SCSSR
No
Yes
TDRE = 1?
Write transmit data to SCTDR and
clear TDRE flag in SCSSR to 0
No
Yes
RDRF = 1?
Read ORER flag in SCSSR
Read RDRF flag in SCSSR
[1] SCI status check and transmit data write:
Read SCSSR and check that the TDRE flag is
set to 1, then write transmit data to SCTDR and
clear the TDRE flag to 0.
Transition of the TDRE flag from 0 to 1 can also
be identified by a TXI interrupt.
[2] Receive error processing:
If a receive error occurs, read the ORER flag in
SCSSR, and after performing the appropriate
error processing, clear the ORER flag to 0.
Reception cannot be resumed if the ORER flag
is set to 1.
[3] SCI status check and receive data read:
Read SCSSR and check that the RDRF flag is
set to 1, then read the receive data in SCRDR
and clear the RDRF flag to 0. Transition of the
RDRF flag from 0 to 1 can also be identified by
an RXI interrupt.
[4] Serial transmission/reception continuation
procedure:
To continue serial transmission/reception,
before the MSB (bit 7) of the current frame is
received, finish reading the RDRF flag, reading
SCRDR, and clearing the RDRF flag to 0. 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 SCTDR and clear the TDRE flag to 0.
Note:
When switching from transmit or receive operation to simultaneous transmit and receive operations, first clear the
TE bit and RE bit to 0, then set both these bits to 1 simultaneously.
Clear TE and RE bits in SCSCR to 0
Write transmit data to SCTDR, and
clear TDRE flag in SCSSR to 0
End of transmission and reception
Figure 12.14 Sample Flowchart for Transmitting/Receiving Serial Data
Summary of Contents for SH7124 R5F7124
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Page 68: ...Section 2 CPU Rev 3 00 Sep 27 2007 Page 48 of 758 REJ09B0243 0300 ...
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