H8S14 Datasheet, PDF (179/938 Pages) Renesas Technology Corp – Renesas 16-Bit Single-Chip Microcomputer H8S Family/H8S/2200 Series

Section 5 Interrupt Controller
5.6.3 Operation
The interrupt controller has three main functions in DTC and DMAC control.
(1) Selection of Interrupt Source
DMAC inputs activation factor directly to each channel. The activation factors for each channel of
DMAC are selected by DTF3 to DTF0 bits of DMACR. The DTA bit of DMABCR can be used to
select whether the selected activation factors are managed by DMAC. By setting the DTA bit to 1,
the interrupt factor which were the activation factor for that DMAC do not act as the DTC
activation factor or the CPU interrupt factor.
Interrupt factors other than the interrupts managed by the DMAC are selected as DTC activation
request or CPU interrupt request by the DTCE bit of the DTCEA to DTCEG of DTC.
By specifying the DISEL bit of the DTC's MRB, it is possible to clear the DTCE bit to 0 after
DTC data transfer, and request a CPU interrupt.
If DTC carries out the designate number of data transfers and the transfer counter reads 0, after
DTC data transfer, the DTCE bit is also cleared to 0, and a CPU interrupt requested.
(2) Determination of Priority
The DTC activation source is selected in accordance with the default priority order, and is not
affected by mask or priority levels. See section 8.4, Interrupts, and section 8.3.3, DTC Vector
Table for the respective priority.
(3) Operation Order
If the same interrupt is selected as a DTC activation source and a CPU interrupt source, the DTC
data transfer is performed first, followed by CPU interrupt exception handling.
If the same interrupt is selected as the DMAC activation factor and as the DTC activation factor or
CPU interrupt factor, these operate independently. They operate in accordance with the respective
operating states and bus priorities.
Table 5.11 shows the interrupt factor clear control and selection of interrupt factors by
specification of the DTA bit of DMAC's DMABCR, DTCE bits of DTC's DTCEA to DTCEG,
and the DISEL bit of DTC's MRB.
Rev.4.00 Sep. 18, 2008 Page 117 of 872
REJ09B0189-0400