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13.4
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 13-12 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 13-12 SCI Interrupt Sources
Interrupt
Channel
Source Description
0
ERI
RXI
TXI
TEI
1
ERI
RXI
TXI
TEI
2
ERI
(H8S/2648,
H8S/2648R,
RXI
H8S/2647)
TXI
TEI
Note: * This table shows the initial state immediately after a reset. Relative priorities among
channels can be changed by means of the interrupt controller.
488
Interrupt due to receive error (ORER, FER, or PER) Not possible
Interrupt due to receive data full state (RDRF)
Interrupt due to transmit data empty state (TDRE)
Interrupt due to transmission end (TEND)
Interrupt due to receive error (ORER, FER, or PER) Not possible
Interrupt due to receive data full state (RDRF)
Interrupt due to transmit data empty state (TDRE)
Interrupt due to transmission end (TEND)
Interrupt due to receive error (ORER, FER, or PER) Not possible
Interrupt due to receive data full state (RDRF)
Interrupt due to transmit data empty state (TDRE)
Interrupt due to transmission end (TEND)
DTC
Activation
Priority*
High
Possible
Possible
Not possible
Possible
Possible
Not possible
Possible
Possible
Not possible
Low
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