Datasheet

Section 15 Serial Communication Interface (SCI, IrDA)
Rev. 3.00 Mar 17, 2006 page 735 of 926
REJ09B0283-0300
In Smart Card interface mode, as in normal serial communication interface mode, transfer can be
carried out using the DTC or DMAC. In transmit operations, 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 or DMAC activation source, the DTC or DMAC 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 or DMAC. In the
event of an error, the SCI retransmits the same data automatically. During this period, the TEND
flag remains cleared to 0 and the DTC or DMAC is not activated. Therefore, the SCI and DTC or
DMAC will automatically transmit the specified number of bytes in the event of an error,
including retransmission. 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 or DMAC, it is essential to set and enable the DTC or
DMAC before carrying out SCI setting. For details on the DTC or DMAC setting procedures,
refer to section 9, Data Transfer Controller (DTC) or section 7, DMA Controller (DMAC).
In receive operations, 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 or DMAC activation source, the DTC or
DMAC 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 or
DMAC. If an error occurs, an error flag is set but the RDRF flag is not. Consequently, the DTC or
DMAC is not activated, but instead, an ERI interrupt request is sent to the CPU. Therefore, the
error flag should be cleared.
15.10 Usage Notes
15.10.1 Module Stop Mode Setting
SCI operation can be disabled or enabled using the module stop control register. The initial setting
is for SCI operation to be halted. Register access is enabled by clearing module stop mode. For
details, refer to section 22, Power-Down Modes.
15.10.2 Break Detection and Processing
When framing error detection is performed, a break can be detected by reading the RxD pin value
directly. In a break, the input from the RxD pin becomes all 0s, and so the FER flag is set, and the
PER flag may also be set. Note that, since the SCI continues the receive operation after receiving a
break, even if the FER flag is cleared to 0, it will be set to 1 again.