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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 17-4 shows a flowchart for transmitting, and figure 17-5 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 17-6.
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 Operation and Data Transfer Operation by DTC below.
Note: For block transfer mode, see section 16.3.2, Operation in Asynchronous Mode.
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