R8CSLASH20 datasheet(127/501 Pages) RENESAS

127 / 501 page

R8C/20 Group, R8C/21 Group

12. Interrupts

Rev.2.00

Aug 27, 2008

Page 111 of 458

REJ09B0250-0200

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, the changes of interrupt sources include all sources that change the interrupt sources assigned to

individual software interrupt numbers, polarities, and timing. Therefore, when a mode change of the peripheral

functions involves interrupt sources, 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 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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