Sci Interrupts - Hitachi H8S/2338 Series Hardware Manual

11.4

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 11-12 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 DMAC or
DTC to perform data transfer. The TDRE flag is cleared to 0 automatically when data transfer is
performed by the DMAC or DTC. The DMAC and 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 DMAC or DTC to perform data transfer. The RDRF flag is cleared to 0 automatically
when data transfer is performed by the DMAC or DTC. The DMAC and DTC cannot be activated
by an ERI interrupt request.
Also note that the DMAC cannot be activated by an SCI channel 2 interrupt.
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