HD6432351 datasheet(663/1025 Pages) RENESAS

663 / 1025 page

Section 14 Smart Card Interface

Rev. 3.00 Sep 15, 2006 page 629 of 988

REJ09B0330-0300

Serial Data Transmission

As data transmission in smart card mode involves error signal sampling and retransmission

processing, the processing procedure is different from that for the normal SCI. Figure 14.4 shows

a flowchart for transmitting, and figure 14.5 shows the relation between a transmit operation and

the internal registers.

[1] Perform Smart Card interface mode initialization as described above in Initialization.

[2] Check that the ERS error flag in SSR is cleared to 0.

[3] Repeat steps [2] and [3] until it can be confirmed that the TEND flag in SSR is set to 1.

[4] Write the transmit data to TDR, clear the TDRE flag to 0, and perform the transmit operation.

The TEND flag is cleared to 0.

[5] When transmitting data continuously, go back to step [2].

[6] To end transmission, clear the TE bit to 0.

With the above processing, interrupt servicing or data transfer by the DMAC or DTC is possible.

If transmission ends and the TEND flag is set to 1 while the TIE bit is set to 1 and interrupt

requests are enabled, a transmit data empty interrupt (TXI) request will be generated. If an error

occurs in transmission and the ERS flag is set to 1 while the RIE bit is set to 1 and interrupt

requests are enabled, a transfer error interrupt (ERI) request will be generated.

The timing for setting the TEND flag depends on the value of the GM bit in SMR. The TEND flag

set timing is shown in figure 14.6.

If the DMAC or DTC is activated by a TXI request, the number of bytes set in the DMAC or DTC

can be transmitted automatically, including automatic retransmission.

For details, see Interrupt Operations and Data Transfer Operation by DMAC or DTC below.

HD6432351 Datasheet(PDF) 663 Page - Renesas Technology Corp