
R8C/14 Group, R8C/15 Group 20. Precautions
Rev.2.10 Jan 19, 2006 Page 237 of 253
REJ09B0164-0210
20.2.5 Changing Interrupt Factor
The IR bit in the interrupt control register may be set to “1” (interrupt requested) when the interrupt
factor changes. When using an interrupt, set the IR bit to “0” (no interrupt requested) after changing
the interrupt factor.
In addition, the changes of interrupt factors include all factors that change the interrupt factors
assigned to individual software interrupt numbers, polarities, and timing. Therefore, when a mode
change of the peripheral functions involves interrupt factors, edge polarities, and timing, Set the IR bit
to “0” (no interrupt requested) after the change. Refer to each peripheral function for the interrupts
caused by the peripheral functions.
Figure 20.1 shows an Example of Procedure for Changing Interrupt Factor.
Figure 20.1 Example of Procedure for Changing Interrupt Factor
NOTES :
1. Execute the above setting individually. Do not execute
2 or more settings at once (by one instruction).
2. Use the I flag for the INTi (i=0 to 3) interupt.
To prevent interrupt requests from being generated when
using peripheral function interupts other than the INTi
interrupt, disable the peripheral function before changing
the interrupt factor. In this case, use the I flag when all
maskable interrupts can be disabled. When all maskable
interrupts cannot be disabled, use the ILVL0 to ILVL2 bits of
interrupt whose factor is changed.
3. Refer to the 21.2.6 Changing Interrupt Control Register
for the instructions to be used and their usage notes.
Interrupt Factor Change
Disable Interrupt
(2, 3)
Set the IR bit to "0" (interrupt not requested) using
the MOV instruction
(3)
Change Interrupt Factor (including mode
of peripheral functions)
Enable Interrupt
(2, 3)
Change Completed
IR Bit: The interrupt control register bit of an
interrupt whose factor is changed.
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