R8C/1A Group, R8C/1B Group 12. Interrupts
Rev.1.30 Dec 08, 2006 Page 101 of 315
REJ09B0252-0130
12.5.5 Changing Interrupt Sources
The IR bit in the interrupt control register may be set to 1 (interrupt requested) when the interrupt source
changes. When using an interrupt, set the IR bit to 0 (no interrupt requested) after changing the interrupt source.
In addition, changes of interrupt sources include all factors that change the interrupt sources assigned to
individual software interrupt numbers, polarities, and timing. Therefore, if a mode change of a peripheral
function involves interrupt sources, edge polarities, and timing, set the IR bit to 0 (no interrupt requested) after
the change. Refer to the individual peripheral function for its related interrupts.
Figure 12.20 shows an Example of Procedure for Changing Interrupt Sources.
Figure 12.20 Example of Procedure for Changing Interrupt Sources
NOTES:
1. Execute the above settings individually. Do not execute two
or more settings at once (by one instruction).
2. Use the I flag for the INTi (i = 0 to 3) interrupts.
To prevent interrupt requests from being generated when
using peripheral function interrupts other than the INTi
interrupt, disable the peripheral function before changing
the interrupt source. In this case, use the I flag if all
maskable interrupts can be disabled. If all maskable
interrupts cannot be disabled, use bits ILVL0 to ILVL2 of
the interrupt whose source is changed.
3. Refer to
12.5.6 Changing Interrupt Control Register for
the instructions to be used and usage notes.
Interrupt source change
Disable interrupts
(2, 3)
Set the IR bit to 0 (interrupt not requested)
using the MOV instruction
(3)
Change interrupt source (including mode
of peripheral function)
Enable interrupts
(2, 3)
Change completed
IR bit: The interrupt control register bit of an
interrupt whose source is changed.
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