Datasheet

Section 13 Smart Card Interface
Rev.7.00 Feb. 14, 2007 page 524 of 1108
REJ09B0089-0700
Data Transfer Operation by DTC: In smart card mode, as with the normal SCI, transfer can be
carried out using the DTC. In a transmit operation, the TDRE flag is also set to 1 at the same time
as the TEND flag in SSR, and a TXI interrupt is generated. If the TXI request is designated
beforehand as a DTC activation source, the DTC will be activated by the TXI request, and transfer
of the transmit data will be carried out. The TDRE and TEND flags are automatically cleared to 0
when data transfer is performed by the DTC. In the event of an error, the SCI retransmits the same
data automatically. Thus, the number of bytes specified by the SCI is transmitted automatically
even in retransmission following an error. However, the ERS flag is not cleared automatically
when an error occurs, and so the RIE bit should be set to 1 beforehand so that an ERI request will
be generated in the event of an error, and the ERS flag will be cleared.
When performing transfer using the DTC, it is essential to set and enable the DTC before carrying
out SCI setting. For details of the DTC setting procedures, see section 7, Data Transfer Controller.
In a receive operation, an RXI interrupt request is generated when the RDRF flag in SSR is set to
1. If the RXI request is designated beforehand as a DTC activation source, the DTC will be
activated by the RXI request, and transfer of the receive data will be carried out. The RDRF flag is
cleared to 0 automatically when data transfer is performed by the DTC. If an error occurs, an error
flag is set but the RDRF flag is not. Consequently, the DTC is not activated, but instead, an ERI
interrupt request is sent to the CPU. Therefore, the error flag should be cleared.
Note: For details of operation in block transfer mode, see section 12.4, SCI Interrupts.