RX610 Group
10. ICU
R01UH0032EJ0120 Rev.1.20
Page 245 of 1006
Feb 20, 2013
Figure 10.6 shows how the IR flag in IRi operates in the case of level detection of an external interrupt.
If the setting of the IRQMD[1:0] bits in IRQCRn is for detection of the external interrupt as the low level of the signal,
the interrupt source should maintain the low level on the IRQn pin until handling of the given interrupt. After that, the
interrupt exception handling routine should return the input on the IRQn pin to the high level, which leads to clearing of
the IR flag in IRi to 0 after four cycles of the PCLK clock. At least four cycles of PCLK can be secured by, for example,
reading the Bj bit in Pm.PORT for the corresponding I/O pin and checking twice for the high level on the IRQn pin.
Interrupt signal (IRQn
detects low level)
IR flag in IRi
After acceptance of the interrupt, the signal
on the IRQn pin is set to the high level.
0 is written to the IR flag in IRi.
CPU
Interrupt handling
Figure 10.6 Operation of the IR Flag in IRi in the Case of Level Detection of an External Interrupt
Once the IR flag in IRi has been set to 1, if the interrupt is disabled at its source, that is, if output of the interrupt is
disabled by the interrupt enable bit of the corresponding peripheral module or detection of an external interrupt on pin
IRQn is disabled by the IRQEN bit in IRQERn, the IR flag in IRi is cleared. Figure 10.7 shows operation when the
interrupt is disabled at its source.
Interrupt signal
IR flag in IRi
Disabling leads to clearing of the
IR flag in IRi.
Enabling/disabling the interrupt.
Enabled
Disabled
Figure 10.7 Relation between the IR Flag in IRi and Disabling of the Interrupt Source
Summary of Contents for RX600 Series
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