SH7721 datasheet(1069/1524 Pages) RENESAS

1069 / 1524 page

Section 30

SIM Card Module (SIM)

Rev. 3.00 Jan. 18, 2008 Page 1007 of 1458

REJ09B0033-0300

30.4.2

Data Format

Figure 30.2 shows the data format used by the smart card interface. The smart card interface

performs a parity check for each frame during reception.

During reception in T = 0 mode, if a parity error is detected, an error signal is returned to the

transmit side, requesting data retransmission. When the transmit side samples the error signal, it

retransmits the same data.

During reception in T = 1 mode, if a parity error is detected, an error signal is not returned. During

transmission, error signals are not sampled and data is not retransmitted.

When no parity error occurs

When a parity error occurs in T=0 mode

When a parity error occurs in T=1 mode

Transmitter output

Receiver output

Ds: Start bit, D0 to D7: Data bits, Dp: Parity bit, DE: Error signal

Figure 30.2

Data Format Used by Smart Card Interface

The operation sequence is as follows.

1. When not in use, the data line is in a high-impedance state and fixed at high level by a pull-up

resistance.

2. The transmit side initiates transmission of one frame of data. The data frame begins with the

start bit (Ds: low level). This is followed by eight data bits (D0 to D7) and the parity bit (Dp).

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