Datasheet
Section 12 Serial Communication Interface (SCI)
Rev.7.00 Feb. 14, 2007 page 490 of 1108
REJ09B0089-0700
12.4 SCI Interrupts
The SCI has four interrupt sources: the transmit-end interrupt (TEI) request, receive-error interrupt
(ERI) request, receive-data-full interrupt (RXI) request, and transmit-data-empty interrupt (TXI)
request. Table 12.12 shows the interrupt sources and their relative priorities. Individual interrupt
sources can be enabled or disabled with the TIE, RIE, and TEIE bits in the SCR. Each kind of
interrupt request is sent to the interrupt controller independently.
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 can activate the DTC to
perform data transfer. The TDRE flag is cleared to 0 automatically when data transfer is
performed by the DTC. The DTC cannot be activated by a TEI interrupt request.
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 DTC to perform data transfer. The RDRF flag is cleared to 0 automatically when data
transfer is performed by the DTC. The DTC cannot be activated by an ERI interrupt request.
Table 12.12 SCI Interrupt Sources
Channel
Interrupt
Source
Description
DTC
Activation
Priority
*
0 ERI Interrupt due to receive error
(ORER, FER, or PER)
Not
possible
High
RXI Interrupt due to receive data full state
(RDRF)
Possible
TXI Interrupt due to transmit data empty state
(TDRE)
Possible
TEI Interrupt due to transmission end
(TEND)
Not
possible
1 ERI Interrupt due to receive error
(ORER, FER, or PER)
Not
possible
RXI Interrupt due to receive data full state
(RDRF)
Possible
TXI Interrupt due to transmit data empty state
(TDRE)
Possible
TEI Interrupt due to transmission end
(TEND)
Not
possible
Low
Note: * This table shows the initial state immediate after a reset. Relative priorities among channels
can be changed by the interrupt controller.