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Section 16 Serial Communication Interface (SCI, IrDA, and CRC)
Data transmission/reception using the DTC is also possible in smart card interface mode, similar
to in the normal SCI mode. In transmission, the TEND and TDRE flags in SSR are simultaneously
set to 1, thus generating a TXI interrupt request. This activates the DTC by a TXI interrupt request
thus allowing transfer of transmit data if the TXI interrupt request is specified as a source of DTC
activation beforehand. The TDRE and TEND flags are automatically cleared to 0 at data transfer
by the DTC. If an error occurs, the SCI automatically re-transmits the same data. During re-
transmission, the TEND flag remains as 0, thus not activating the DTC. Therefore, the SCI and
DTC automatically transmit the specified number of bytes, including re-transmission in the case of
error occurrence. However, the ERS flag in SSR, which is set at error occurrence, is not
automatically cleared; the ERS flag must be cleared by previously setting the RIE bit in SCR to 1
to enable an ERI interrupt request to be generated at error occurrence.
When transmitting/receiving data using the DTC, be sure to set and enable the DTC prior to
making SCI settings. For DTC settings, see section 7, Data Transfer Controller (DTC).
In reception, an RXI interrupt request is generated when the RDRF flag in SSR is set to 1. This
activates the DTC by an RXI interrupt request thus allowing transfer of receive data if the RXI
interrupt request is specified as a source of DTC activation beforehand. The RDRF flag is
automatically cleared to 0 at data transfer by the DTC. If an error occurs, the RDRF flag is not set
but the error flag is set. Therefore, the DTC is not activated and an ERI interrupt request is issued
to the CPU instead; the error flag must be cleared.
When the DTE bit in TDRE in SCIDTER_0 and SCIDTER_2 is 1, TXI_0 and TXI_2 interrupt
requests are masked, and when the DTE bit in RDRF is 1, RXI0 and RXI2 interrupt requests are
masked.
16.10
Usage Notes
16.10.1 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, see section 27, Power-Down Modes.
16.10.2 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 in SSR is set,
and the PER flag may also be set. Note that, since the SCI continues the receive operation even
after receiving a break, even if the FER flag is cleared to 0, it will be set to 1 again.
Rev. 3.00 Jan 25, 2006 page 461 of 872
REJ09B0286-0300
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