H8SLASH3021 datasheet(403/712 Pages) RENESAS

403 / 712 page

11. Serial Communication Interface

Rev.2.00 Mar. 22, 2007 Page 379 of 684

REJ09B0352-0200

Transmitting and Receiving Data

SCI Initialization (Synchronous Mode): Before transmitting or receiving, clear the TE and RE

bits to 0 in SCR, then initialize the SCI as follows.

When changing the communication mode or format, always clear the TE and RE bits to 0 before

following the procedure given below. Clearing the TE bit to 0 sets the TDRE flag to 1 and

initializes TSR. Clearing the RE bit to 0, however, does not initialize the RDRF, PER, FER, and

ORE flags and RDR, which retain their previous contents.

Figure 11.15 shows a sample flowchart for initializing the SCI.

Clear TE and RE

bits to 0 in SCR

1 bit interval

elapsed?

Start transmitting or receiving

Yes

Select the clock source in SCR. Clear the RIE, TIE, TEIE,

MPIE, TE, and RE bits to 0.

Select the communication format in SMR.

Write the value corresponding to the bit rate in BRR.

This step is not necessary when an external clock is used.

Note: In simultaneous transmitting and receiving, the TE and RE

bits should be cleared to 0 or set to 1 simultaneously.

Set CKE1 and CKE0 bits in

SCR (leaving TE and RE

bits cleared to 0)

Set TE or RE to 1 in SCR

Set RIE, TIE, and TEIE

bits as necessary

Wait

Wait for at least the interval required to transmit or receive

one bit, then set the TE or RE bit to 1 in SCR. Also set

the RIE, TIE, and TEIE bits as necessary.

Setting the TE or RE bit enables the SCI to use the

TxD or RxD pin.

Start of initialization

Set value in BRR

Select communication

format in SMR

Figure 11.15 Sample Flowchart for SCI Initialization

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