R8C2K datasheet(126/471 Pages) RENESAS

126 / 471 page

R8C/2K Group, R8C/2L Group

12. Interrupts

Rev.1.10

Dec 21, 2007

Page 109 of 450

REJ09B0406-0110

12.1.6.8

Returning from an Interrupt Routine

When the REIT instruction is executed at the end of an interrupt routine, the FLG register and PC, which have

been saved to the stack, are automatically restored. The program, that was running before the interrupt request

was acknowledged, starts running again.

Restore registers saved by a program in an interrupt routine using the POPM instruction or others before

executing the REIT instruction.

12.1.6.9

Interrupt Priority

If two or more interrupt requests are generated while a single instruction is being executed, the interrupt with

the higher priority is acknowledged.

Set bits ILVL2 to ILVL0 to select the desired priority level for maskable interrupts (peripheral functions).

However, if two or more maskable interrupts have the same priority level, their interrupt priority is resolved by

hardware, and the higher priority interrupts acknowledged.

The priority levels of special interrupts, such as reset (reset has the highest priority) and watchdog timer, are set

by hardware.

Figure 12.10 shows the Priority Levels of Hardware Interrupts.

The interrupt priority does not affect software interrupts. The MCU jumps to the interrupt routine when the

instruction is executed.

Figure 12.10

Priority Levels of Hardware Interrupts

Address break

Watchdog timer

Oscillation stop detection

Voltage monitor 1

Voltage monitor 2

Peripheral function

Single step

Address match

High

Low

Reset

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