Interrupts; Interrupts In Normal Serial Communication Interface Mode - Hitachi H8S/2215 Series Hardware Manual

13.8

Interrupts

13.8.1

Interrupts in Normal Serial Communication Interface Mode

Table 13.10 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 can activate the DTC or
DMAC to perform data transfer. The TDRE flag is cleared to 0 automatically when data is
transferred by the DTC or 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
request can activate the DTC or DMAC to transfer data. The RDRF flag is cleared to 0
automatically when data is transferred by the DTC or DMAC.
A TEI interrupt is requested when the TEND flag is set to 1 and 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, if the TDRE and TEND flags are cleared simultaneously by the TXI
interrupt routine, the SCI cannot branch to the TEI interrupt routine later.
Rev. 3.0, 10/02, page 408 of 686