HD64F3048F16 Datasheet, PDF (559/903 Pages) Renesas Technology Corp – Old Company Name in Catalogs and Other Documents

Section 14 Smart Card Interface
Transmitting Serial Data
The transmitting procedure in smart card mode is different from the normal SCI procedure,
because of the need to sample the error signal and retransmit. Figure 14.4 shows a flowchart for
transmitting, and figure 14.5 shows the relation between a transmit operation and the internal
registers.
1. Initialize the smart card interface by the procedure given above in Initialization.
2. Check that the ERS error flag is cleared to 0 in SSR.
3. Check that the TEND flag is set to 1 in SSR. Repeat steps 2 and 3 until this check passes.
4. Write transmit data in TDR and clear the TDRE flag to 0. The data will be transmitted and the
TEND flag will be cleared to 0.
5. To continue transmitting data, return to step 2.
6. To terminate transmission, clear the TE bit to 0.
This procedure may include interrupt handling and DMA transfer.
If the TIE bit is set to 1 to enable interrupt requests, when transmission is completed and the
TEND flag is set to 1, a transmit-data-empty interrupt (TXI) is requested. If the RIE bit is set to 1
to enable interrupt requests, when a transmit error occurs and the ERS flag is set to 1, a
transmit/receive-error interrupt (ERI) is requested.
The timing of TEND flag setting depends on the GM bit in SMR. The timing is shown in figure
14.6.
If the TXI interrupt activates the DMAC, the number of bytes designated in the DMAC can be
transmitted automatically, including automatic retransmit.
For details, see Interrupt Operations and Data Transfer by DMAC in this section.
Rev. 3.00 Sep 27, 2006 page 531 of 872
REJ09B0325-0300