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Section 19 Serial Communication Interface with FIFO (SCIF)
Rev. 4.00 Sep. 14, 2005 Page 741 of 982
REJ09B0023-0400
• Transmitting and Receiving Serial Data Simultaneously (Synchronous Mode)
Figure 19.18 shows a sample flowchart for transmitting and receiving serial data simultaneously.
Use the following procedure for the simultaneous transmission/reception of serial data, after
enabling the SCIF for transmission/reception.
Start of transmission and reception
Initialization
Read TDFE flag in SCFSR
TDFE = 1?
Write transmit data to SCFTDR,
and clear TDFE flag
in SCFSR to 0
Read ORER flag in SCLSR
ORER = 1?
Read RDF flag in SCFSR
RDF = 1?
Clear TE and RE bits
in SCSCR to 0
End of transmission and reception
Read receive data in
SCFRDR, and clear RDF
flag in SCFSR to 0
All data received?
No
No
Yes
No
No
Yes
Yes
[1] SCIF status check and transmit data
write:
Read SCFSR and check that the
TDFE flag is set to 1, then write
transmit data to SCFTDR, and clear
the TDFE flag to 0. The transition of
the TDFE flag from 0 to 1 can also be
identified by a TXI interrupt.
[2] Receive error handling:
Read the ORER flag in SCLSR to
identify any error, perform the
appropriate error handling, then clear
the ORER flag to 0. Reception cannot
be resumed while the ORER flag is
set to 1.
[3] SCIF status check and receive data
read:
Read SCFSR and check that RDF =
1, then read the receive data in
SCFRDR, and clear the RDF flag to
0. The transition of the RDF flag from
0 to 1 can also be identified by an RXI
interrupt.
[4] Serial transmission and reception
continuation procedure:
To continue serial transmission and
reception, read 1 from the RDF flag
and the receive data in SCFRDR, and
clear the RDF flag to 0 before
receiving the MSB in the current
frame. Similarly, read 1 from the
TDFE flag to confirm that writing is
possible before transmitting the MSB
in the current frame. Then write data
to SCFTDR and clear the TDFE flag
to 0.
[1]
Yes
Error handling
[4]
When switching from a transmit operation
or receive operation to simultaneous
transmission and reception operations,
clear the TE and RE bits to 0, and then
set them simultaneously to 1.
Note:
[3]
[2]
Figure 19.18 Sample Flowchart for Transmitting/Receiving Serial Data