Section 12 Serial Communication Interface (SCI)
Rev. 3.00 Mar. 14, 2006 Page 440 of 804
REJ09B0104-0300
12.8 Interrupt
Sources
12.8.1
Interrupts in Normal Serial Communication Interface Mode
Table 12.12 shows the interrupt sources in normal serial communication interface mode. A
different interrupt vector is assigned to each interrupt source, and individual interrupt sources can
be enabled or disabled using the enable bits in SCR.
When the TDRE flag in SSR is set to 1, a TXI interrupt request is generated. When the TEND flag
in SSR is set to 1, a TEI interrupt request is generated. A TXI interrupt request can activate the
DMAC to allow data transfer. The TDRE flag is automatically cleared to 0 at data transfer by the
DMAC.
When the RDRF flag in SSR is set to 1, an RXI interrupt request is generated. When the ORER,
PER, or FER flag in SSR is set to 1, an ERI interrupt request is generated. An RXI interrupt can
activate the DMAC to allow data transfer. The RDRF flag is automatically cleared to 0 at data
transfer by the DMAC.
A TEI interrupt is requested when the TEND flag is set to 1 while the TEIE bit is set to 1. If a TEI
interrupt and a TXI interrupt are requested simultaneously, the TXI interrupt has priority for
acceptance. However, note that if the TDRE and TEND flags are cleared to 0 simultaneously by
the TXI interrupt processing routine, the SCI cannot branch to the TEI interrupt processing routine
later.
Table 12.12 SCI Interrupt Sources
Name Interrupt
Source
Interrupt
Flag DMAC
Activation
Priority
ERI
Receive error
ORER, FER, or PER
Not possible
High
RXI
Receive data full
RDRF
Possible
TXI Transmit
data
empty
TDRE
Possible
TEI
Transmit end
TEND
Not possible
Low
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