H8S2245 datasheet(483/818 Pages) RENESAS

483 / 818 page

Section 12 Serial Communication Interface (SCI)

Rev.3.00 Mar. 26, 2007 Page 441 of 772

REJ09B0355-0300

Serial data reception (asynchronous mode): Figure 12.7 shows a sample flowchart for serial

reception.

The following procedure should be used for serial data reception.

Yes

<End>

[1]

Initialization

Start reception

[2]

Yes

Read RDRF flag in SSR

[4]

[5]

Clear RE bit in SCR to 0

Read ORER, PER, and

FER flags in SSR

Error processing

(Continued on next page)

[3]

Read receive data in RDR, and

clear RDRF flag in SSR to 0

Yes

PER

∨ FER ∨ ORER = 1?

RDRF = 1?

All data received?

SCI initialization:

The RxD pin is automatically

designated as the receive data

input pin.

Receive error processing and

break detection:

If a receive error occurs, read the

ORER, PER, and FER flags in

SSR to identify the error. After

performing the appropriate error

processing, ensure that the

ORER, PER, and FER flags are

all cleared to 0. Reception cannot

be resumed if any of these flags

are set to 1. In the case of a

framing error, a break can be

detected by reading the value of

the input port corresponding to

the RxD pin.

SCI status check and receive

data read :

Read SSR and check that RDRF

= 1, then read the receive data in

RDR and clear the RDRF flag to

0. Transition of the RDRF flag

from 0 to 1 can also be identified

by an RXI interrupt.

Serial reception continuation

procedure:

To continue serial reception,

before the stop bit for the current

frame is received, read the

RDRF flag, read RDR, and clear

the RDRF flag to 0. The RDRF

flag is cleared automatically

when the DTC* is activated by

an RXI interrupt and the RDR

value is read.

[1]

[2] [3]

[4]

[5]

Note: * The case, in which the DTC automatically clears the RDRF flag, occurs only when DISEL in

DTC is 0 with the transfer counter not being 0. Therefore, the RDRF flag should be cleared

by CPU when DISEL is 1, or when DISEL is 0 with the transfer counter being 0.

Figure 12.7 Sample Serial Reception Data Flowchart

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