HD64F36022 datasheet(222/384 Pages) RENESAS

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Section 13 Serial Communication Interface 3 (SCI3)

Rev. 4.00 Sep. 23, 2005 Page 196 of 354

REJ09B0025-0400

13.4.4

Serial Data Reception

Figure 13.7 shows an example of operation for reception in asynchronous mode. In serial

reception, the SCI3 operates as described below.

1. The SCI3 monitors the communication line. If a start bit is detected, the SCI3 performs

internal synchronization, receives receive data in RSR, and checks the parity bit and stop bit.

2. If an overrun error occurs (when reception of the next data is completed while the RDRF flag

is still set to 1), the OER bit in SSR is set to 1. If the RIE bit in SCR3 is set to 1 at this time, an

ERI interrupt request is generated. Receive data is not transferred to RDR.

3. If a parity error is detected, the PER bit in SSR is set to 1 and receive data is transferred to

RDR. If the RIE bit in SCR3 is set to 1 at this time, an ERI interrupt request is generated.

4. If a framing error is detected (when the stop bit is 0), the FER bit in SSR is set to 1 and receive

data is transferred to RDR. If the RIE bit in SCR3 is set to 1 at this time, an ERI interrupt

request is generated.

5. If reception is completed successfully, the RDRF bit in SSR is set to 1, and receive data is

transferred to RDR. If the RIE bit in SCR3 is set to 1 at this time, an RXI interrupt request is

generated. Continuous reception is possible because the RXI interrupt routine reads the receive

data transferred to RDR before reception of the next receive data has been completed.

1 frame

Start

bit

Start

bit

Receive

data

Receive

data

Parity

bit

Stop

bit

Parity

bit

Stop

bit

Mark state

(idle state)

1 frame

1D0

0/1

0D0

0/1

Serial

data

RDRF

FER

LSI

operation

User

processing

RDRF

cleared to 0

RDR data read

Framing error

processing

RXI request

0 stop bit

detected

ERI request in

response to

framing error

Figure 13.7 Example of SCI3 Reception in Asynchronous Mode

(8-Bit Data, Parity, One Stop Bit)

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