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With the above processing, interrupt servicing is possible.
If reception ends and the RDRF flag is set to 1 while the RIE bit is set to 1 and interrupt requests
are enabled, a receive data full interrupt (RXI) request will be generated. If an error occurs in
reception and either the ORER flag or the PER flag is set to 1, a transfer error interrupt (ERI)
request will be generated.
For details, see Interrupt Operation below.
If a parity error occurs during reception and the PER is set to 1, the received data is still
transferred to RDR, and therefore this data can be read.
Mode Switching Operation: When switching from receive mode to transmit mode, first confirm
that the receive operation has been completed, then start from initialization, clearing RE bit to 0
and setting TE bit to 1. The RDRF flag or the PER and ORER flags can be used to check that the
receive operation has been completed.
When switching from transmit mode to receive mode, first confirm that the transmit operation has
been completed, then start from initialization, clearing TE bit to 0 and setting RE bit to 1. The
TEND flag can be used to check that the transmit operation has been completed.
Interrupt Operation: There are three interrupt sources in smart card interface mode: transmit
data empty interrupt (TXI) requests, transfer error interrupt (ERI) requests, and receive data full
interrupt (RXI) requests. The transmit end interrupt (TEI) request is not used in this mode.
When the TEND flag in SSR is set to 1, a TXI interrupt request is generated.
When the RDRF flag in SSR is set to 1, an RXI interrupt request is generated.
When any of flags ORER, PER, and ERS in SSR is set to 1, an ERI interrupt request is generated.
The relationship between the operating states and interrupt sources is shown in table 12-8.
Table 12-8 Smart Card Mode Operating States and Interrupt Sources
Operating State
Transmit
Normal
Mode
operation
Error
Receive
Normal
Mode
operation
Error
Flag
Mask Bit
TEND
TIE
ERS
RIE
RDRF
RIE
PER, ORER
RIE
Interrupt Source
TXI
ERI
RXI
ERI
407
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