RX610 Group
10. ICU
R01UH0032EJ0120 Rev.1.20
Page 243 of 1006
Feb 20, 2013
10.4.2
Interrupt Status Flag
The interrupt status flag (IR flag) in IRi detects the corresponding interrupt signal and retains an indication that the
request was generated.
There are two ways to detect interrupt sources: level detection and edge detection.
For interrupts from peripheral modules, detection is by either edge or level according to the source.
For the IRQn pins (n = 0 to 15) as interrupt sources, edge or level detection can be selected by the setting of the
IRQMD[1:0] bits in IRQCRn.
For the interrupt request and the corresponding detection method of each interrupt request source, see table 10.4,
Interrupt Vector Table.
10.4.2.1
Interrupt Status Flag in Edge Detection
Figure 10.2 shows the operation of the IR flag in IRi in the case of edge detection of peripheral module interrupts and
external interrupts.
When an interrupt signal is generated, the IR flag in IRi is set to 1 and the interrupt request is conveyed to the selected
destination immediately after the point of transition of the interrupt signal. If the destination accepts the interrupt request,
the IR flag in IRi is automatically cleared to 0. Therefore, the software being executed does not have to clear the IR flag.
Interrupt signal
IR flag in IRi
Acceptance of interrupt
request by destination
Figure 10.2 Operation of the IR Flag in IRi in the Case of Edge Detection
While the IR flag in IRi is set to 1 because an interrupt signal has been generated, re-generation of the interrupt signal is
ignored. If the interrupt signal is generated after the IR flag in IRi has been cleared, the IR flag in IRi is re-set. Figure
10.3 shows the timing for re-setting of the IR flag in IRi.
When the communication function (SCI/RIIC) is combined with DTC/DMAC function, an interrupt request is ignored,
and a transfer request may be lost. For details, refer to section 10.7.3, Notes on Transferring DMAC/DTC Using
Communication Function (SCI, RIIC).
Interrupt signal
IR flag in IRi
(1)
(2)
(3)
IR flag in IRi is cleared (1)
IR flag in IRi is cleared (3)
Interrupt source signal (2) is ignored
because the IR flag in IRi is still set to 1.
Figure 10.3 Timing for Re-setting the IR Flag in IRi