Renesas M16C/29 Series Hardware Manual page 440

M16C/29 Group
1.5.4 Changing the Interrupt Generate Factor
If the interrupt generate factor is changed, the IR bit in the interrupt control register for the changed
interrupt may inadvertently be set to "1" (interrupt requested). If you changed the interrupt generate factor
for an interrupt that needs to be used, be sure to clear the IR bit for that interrupt to "0" (interrupt not
requested).
"Changing the interrupt generate factor" referred to here means any act of changing the source, polarity
or timing of the interrupt assigned to each software interrupt number. Therefore, if a mode change of any
peripheral function involves changing the generate factor, polarity or timing of an interrupt, be sure to
clear the IR bit for that interrupt to "0" (interrupt not requested) after making such changes. Refer to the
description of each peripheral function for details about the interrupts from peripheral functions.
Figure 1.5.1 shows the procedure for changing the interrupt generate factor.
Change the interrupt generate factor (including a mode change of peripheral function)
Use the MOV instruction to clear the IR bit to "0" (interrupt not requested) (Note 3)
IR bit: A bit in the interrupt control register for the interrupt whose interrupt generate factor is to
Note 1: The above settings must be executed individually. Do not execute two or more settings
Note 2: Use the I flag for the INTi interrupt (i = 0 to 5).
Note 3: Refer to Section 1.1.6, "Rewrite the Interrupt Control Register" for details about the
Figure 1.5.1. Procedure for Changing the Interrupt Generate Factor
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1.5.5 INT Interrupt
1. Either an "L" level of at least t
input to pins INT
2. If the POL bit in the INT0IC to INT5IC registers or the IFSR7 to IFSR0 bits in the IFSR register are
changed, the IR bit may inadvertently set to 1 (interrupt requested). Be sure to clear the IR bit to 0
(interrupt not requested) after changing any of those register bits.
Rev.1.00 Nov 01,2004
REJXXXXXXX-0100Z
Changing the interrupt source
Disable interrupts (Note 2, Note 3)
Enable interrupts (Note 2, Note 3)
End of change
be changed
simultaneously (using one instruction).
For the interrupts from peripheral functions other than the INTi interrupt, turn off the
peripheral function that is the source of the interrupt in order not to generate an interrupt
request before changing the interrupt generate factor. In this case, if the maskable interrupts
can all be disabled without causing a problem, use the I flag. Otherwise, use the corresponding
ILVL2 to ILVL0 bit for the interrupt whose interrupt generate factor is to be changed.
instructions to use and the notes to be taken for instruction execution.
( ) or an "H" level of at least t
W INH
through INT regardless of the CPU operation clock.
0 5
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( ) width is necessary for the signal
W INL