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Renesas SH7641 User Manual

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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

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