H8SLASH3003 datasheet(474/715 Pages) RENESAS

474 / 715 page

Transmitting Serial Data (Asynchronous Mode): Figure 13-5 shows a sample flowchart for

transmitting serial data and indicates the procedure to follow.

Figure 13-5 Sample Flowchart for Transmitting Serial Data

Start transmitting

Read TDRE flag in SSR

TDRE = 1?

Write transmit data

in TDR and clear TDRE

flag to 0 in SSR

All data

transmitted?

End

Yes

SCI initialization: the transmit data output function

of the TxD pin is selected automatically.

SCI status check and transmit data write: read SSR,

check that the TDRE flag is 1, then write transmit data

in TDR and clear the TDRE flag to 0.

Read TEND flag in SSR

TEND = 1?

Yes

Output break

signal?

Yes

Clear TE bit to 0 in SCR

Clear DR bit to 0,

set DDR bit to 1

Initialize

To continue transmitting serial data: after checking

that the TDRE flag is 1, indicating that data can be

written, write data in TDR, then clear the TDRE

flag to 0. When the DMAC is activated by a transmit-

-data-empty interrupt request (TXI) to write data in TDR,

the TDRE flag is checked and cleared automatically.

To output a break signal at the end of serial transmission:

set the DDR bit to 1 and clear the DR bit to 0

(DDR and DR are I/O port registers), then clear the

TE bit to 0 in SCR.

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H8/3003 Datasheet(PDF) 474 Page - Renesas Technology Corp