M16C80 datasheet(86/358 Pages) RENESAS

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Page 75

9. Interrupt Outline

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Figure 9.12 Switching condition of INT interrupt request

Set the polarity select bit

Clear the interrupt request bit to “0”

Set the interrupt priority level to level 1 to 7

(Enable the accepting of INT interrupt request)

Set the interrupt priority level to level 0

(Disable INT interrupt)

(5) Rewrite the interrupt control register

• When a instruction to rewrite the interrupt control register is executed but the interrupt is disabled, the

interrupt request bit is not set sometimes even if the interrupt request for that register has been gener-

ated. This will depend on the instruction. If this creates problems, use the below instructions to change

the register.

Instructions : AND, OR, BCLR, BSET

• When attempting to clear the interrupt request bit of an interrupt control register, the interrupt request

bit is not cleared sometimes. This will depend on the instruction. If this creates problems, use the

below instructions to change the register.

Instructions : MOV

(6) Address match interrupt

• Do not set the following addresses to the address match interrupt register.

1. The address of the starting instruction in an interrupt routine.

2. Any of the next 7 instructions addresses immediately after an instruction to clear an interrupt request

bit of an interrupt control register or an instruction to rewrite an interrupt priority level to a smaller value.

3. Any of the next 3 instructions addresses immediately after an instruction to set the interrupt enable

flag (I flag).

4. Any of the next 3 instructions addresses immediately after an instruction to rewrite a processor inter-

rupt priority level (IPL) to a smaller value.

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