H8SLASH3003 datasheet(487/715 Pages) RENESAS

487 / 715 page

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 13-15 is a sample flowchart for initializing the SCI.

Figure 13-15 Sample Flowchart for SCI Initialization

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.

Set RIE, TIE, TEIE, MPIE,

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, TEIE, and

MPIE 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, TEIE, and MPIE 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

469

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