H8SLASH3021 datasheet(435/712 Pages) RENESAS

435 / 712 page

12. Smart Card Interface

Rev.2.00 Mar. 22, 2007 Page 411 of 684

REJ09B0352-0200

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 12.4 shows an example of the transmission processing flow, and figure 12.5

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 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.

For details, see the following Interrupt Operations.

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