User's Manual

Table Of Contents
R01UH0823EJ0110 Rev.1.10 Page 302 of 1852
Nov 30, 2020
RX23W Group 15. Interrupt Controller (ICUb)
15.4 Interrupt Operation
The interrupt controller performs the following processing.
Detecting interrupts
Enabling and disabling interrupts
Selecting interrupt request destinations (CPU interrupt, DTC trigger, or DMAC trigger)
Determining priority
15.4.1 Detecting Interrupts
Interrupt requests are detected in either of two ways: the detection of edges of the interrupt signal or the detection of a
level of the interrupt signal.
Edge detection or level detection is selected for the IRQi pins (i = 0, 1, and 4 to 7) as external interrupt requests by the
setting of the IRQMD[1:0] bits in IRQCRi.
For interrupts from peripheral modules, either edge detection or level detection is determined per interrupt source.
For the correspondence between interrupt sources and methods of detection, see Table 15.3, Interrupt Vector Table.
15.4.1.1 Operation of Status Flags for Edge-Detected Interrupts
Figure 15.2 shows the operation of the IR flag in IRn (n = interrupt vector number) in the case of edge detection of an
interrupt from a peripheral module or on an external pin.
The IR flag in IRn is set to 1 immediately after the transition of the interrupt signal due to generation of the interrupt. If
the CPU is the request destination for the interrupt, the IR flag is automatically cleared to 0 on acceptance of the
interrupt. If the DMAC or DTC is the request destination for the interrupt, the IRn.IR flag operation differs according to
the DMAC/DTC transfer settings and transfer count. For details, see Table 15.4, Operation When Starting the
DMAC/DTC.
Figure 15.2 IRn.IR Flag Operation for Edge Detection Interrupts
System clock
Interrupt signal
IRn.IR flag
Peripheral module clock
CPU interrupt request
DTC transfer request
DMA transfer request
*1 *2
Note 1. One of the following requests is issued: CPU interrupt request, DTC transfer request, and DMA transfer request.
For details of the setting, see section 15.4.3, Selecting Interrupt Request Destinations.
Note 2. When the CPU interrupt request is specified, this flag is set to 0 on acceptance of a CPU interrupt. For the timing of 0
setting at the DTC transfer request or DMA transfer request, see Table 15.4, Operation When Starting the DMAC/
DTC.