HD64F36049 datasheet(363/562 Pages) RENESAS

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Section 17 Serial Communication Interface 3 (SCI3)

Rev. 3.00 Mar. 15, 2006 Page 331 of 526

REJ09B0060-0300

17.5.5

Simultaneous Serial Data Transmission and Reception

Figure 17.14 shows a sample flowchart for simultaneous serial transmit and receive operations.

The following procedure should be used for simultaneous serial data transmit and receive

operations. To switch from transmit mode to simultaneous transmit and receive mode, after

checking that the SCI3 has finished transmission and the TDRE and TEND flags are set to 1, clear

TE to 0. Then simultaneously set TE and RE to 1 with a single instruction. To switch from receive

mode to simultaneous transmit and receive mode, after checking that the SCI3 has finished

reception, clear RE to 0. Then after checking that the RDRF and receive error flags (OER, FER,

and PER) are cleared to 0, simultaneously set TE and RE to 1 with a single instruction.

Yes

<End>

Start transmission/reception

[3]

Error processing

[4]

Yes

[1]

Read TDRE flag in SSR

Write transmit data to TDR

Read OER flag in SSR

Read RDRF flag in SSR

Yes

TDRE = 1

OER = 1

RDRF = 1

Read receive data in RDR

Clear TE and RE bits in SCR to 0

All data received?

Yes

[2]

[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 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 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

17.13.

Figure 17.14 Sample Flowchart of Simultaneous Serial Transmit and Receive Operations

(Clocked Synchronous Mode)

HD64F36049 Datasheet(PDF) 363 Page - Renesas Technology Corp

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