SH7261 datasheet(745/1348 Pages) RENESAS

745 / 1348 page

Section 16 Serial Communication Interface with FIFO (SCIF)

Rev. 2.00 Sep. 07, 2007 Page 713 of 1312

REJ09B0320-0200

In serial transmission, the SCIF operates as described below.

1. When data is written into the transmit FIFO data register (SCFTDR), the SCIF transfers the

data from SCFTDR to the transmit shift register (SCTSR) and starts transmitting. Confirm that

the TDFE flag in the serial status register (SCFSR) is set to 1 before writing transmit data to

SCFTDR. The number of data bytes that can be written is (16 – transmit trigger setting).

2. When data is transferred from SCFTDR to SCTSR and transmission is started, consecutive

transmit operations are performed until there is no transmit data left in SCFTDR. When the

number of transmit data bytes in SCFTDR falls below the transmit trigger number set in the

FIFO control register (SCFCR), the TDFE flag is set. If the TIE bit in the serial control register

(SCSR) is set to 1 at this time, a transmit-FIFO-data-empty interrupt (TXI) request is

generated.

The serial transmit data is sent from the TxD pin in the following order.

A. Start bit: One-bit 0 is output.

B. Transmit data: 8-bit or 7-bit data is output in LSB-first order.

C. Parity bit: One parity bit (even or odd parity) is output. (A format in which a parity bit is

not output can also be selected.)

D. Stop bit(s): One or two 1 bits (stop bits) are output.

E. Mark state: 1 is output continuously until the start bit that starts the next transmission is

sent.

3. The SCIF checks the SCFTDR transmit data at the timing for sending the stop bit. If data is

present, the data is transferred from SCFTDR to SCTSR, the stop bit is sent, and then serial

transmission of the next frame is started.

Figure 16.5 shows an example of the operation for transmission.

TDFE

0/1

TEND

Serial

data

Start

bit

Data

Parity

bit

Stop

bit

Start

bit

Idle state

(mark state)

Data

Parity

bit

Stop

bit

TXI interrupt

request

Data written to SCFTDR and TDFE

flag read as 1 then cleared to 0 by

TXI interrupt handler

One frame

TXI interrupt

request

Figure 16.5 Example of Transmit Operation (8-Bit Data, Parity, 1 Stop Bit)

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