R27 datasheet(153/487 Pages) RENESAS

153 / 487 page

R8C/26 Group, R8C/27 Group

12. Interrupts

Rev.2.10

Sep 26, 2008

Page 134 of 453

REJ09B0278-0210

12.6.4

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. To prevent interrupt requests from being generated, 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

12.6.5 Changing Interrupt Control Register

Contents 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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