SH7721 datasheet(1076/1524 Pages) RENESAS

1076 / 1524 page

Section 30

SIM Card Module (SIM)

Rev. 3.00 Jan. 18, 2008 Page 1014 of 1458

REJ09B0033-0300

(2)

Serial Data Transmission

Data transmission in smart card mode includes error signal sampling and retransmit processing.

An example of transmit processing is shown in figure 30.5.

Step (1) to step (6) of figure 30.5 correspond to the following operation.

1. Follow the initialization procedure above to initialize the smart card interface.

2. Confirm that the ERS bit (error flag) in SCSSR is cleared to 0.

3. Repeat steps (2) and (3) until it can be confirmed that the TDRE flag in SCSSR is set to 1.

4. Write transmit data to SCTDR, and perform transmission. At this time, the TDRE flag is

automatically cleared to 0. When transmission of the start bit is started, the TEND flag is

automatically cleared to 0, and the TDRE flag is automatically set to 1.

5. When performing continuous data transmission, return to step (2).

6. When transmission is ended, clear the TE bit to 0.

Interrupt processing can be performed in the above series of processing.

When the TIE bit is set to 1 to enable interrupt requests and if transmission is started and the

TDRE flag is set to 1, a transmit data empty interrupt (TXI) request is issued. When the RIE bit is

set to 1 to enable interrupt requests and if an error occurs during transmission and the ERS flag is

set to 1, a transmit/receive error interrupt (ERI) request is issued.

For details, refer to Interrupt Operations in section 30.4.5, Data Transmit/Receive Operation.

SH7721 Datasheet(PDF) 1076 Page - Renesas Technology Corp