3069RF-ZTAT Datasheet, PDF (557/1003 Pages) Renesas Technology Corp – RENESAS 16-BIT SINGLE-CHIP MICROCOMPUTER

Table 14.8 Smart Card Interface Mode Operating States and Interrupt Sources
Operating State
Transmit Mode
Receive Mode
Normal
operation
Error
Normal
operation
Error
Flag
TEND
Enable Bit
TIE
ERS
RIE
RDRF
RIE
PER, ORER RIE
Interrupt
Source
TXI
ERI
RXI
ERI
DMAC
Activation
Available
Not available
Available
Not available
Data Transfer by DMAC: The DMAC can be used to transmit and receive data in smart card
mode, as in normal SCI operations. In transmit mode, when the TEND flag is set to 1 in SSR, the
TDRE flag is set simultaneously, generating a TXI interrupt. If the TXI request is designated
beforehand as a DMAC activation source, the DMAC will be activated by the TXI request and
will transfer the next transmit data. This data transfer by the DMAC automatically clears the
TDRE and TEND flags to 0. In the event of an error, the SCI automatically retransmits the same
data, keeping the TEND flag cleared to 0 so that the DMAC is not activated. The SCI and DMAC
will therefore automatically transmit the designated number of bytes, including retransmission
when an error occurs. When an error occurs, the ERS flag is not cleared automatically, so the RIE
bit should be set to 1 to enable the error to generate an ERI request, and the ERI interrupt handler
should clear ERS.
When using the DMAC to transmit or receive, first set up and enable the DMAC, then make SCI
settings. DMAC settings are described in section 7, DMA controller.
In receive operations, an RXI interrupt is requested when the RDRF flag is set to 1 in SSR. If the
RXI request is designated beforehand as a DMAC activation source, the DMAC will be activated
by the RXI request and will transfer the received data. This data transfer by the DMAC
automatically clears the RDRF flag to 0. When an error occurs, the RDRF flag is not set and an
error flag is set instead. The DMAC is not activated. The ERI interrupt request is directed to the
CPU. The ERI interrupt handler should clear the error flags.
Rev. 5.0, 09/04, page 535 of 978