M30201 datasheet(49/415 Pages) RENESAS

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Mitsubishi microcomputers

M30201 Group

SINGLE-CHIP 16-BIT CMOS MICROCOMPUTER

Interrupts

Changing the Interrupt Control Register

< Program examples >

The program examples are described as follow:

Example 1:

INT_SWITCH1:

FCLR

; Disable interrupts.

AND.B

#00h, 0055h

; Clear TA0IC int. priority level and int. request bit.

NOP

; Four NOP instructions are required when using HOLD function.

NOP

FSET

; Enable interrupts.

Example 2:

INT_SWITCH2:

FCLR

; Disable interrupts.

AND.B

#00h, 0055h

; Clear TA0IC int. priority level and int. request bit.

MOV.W

MEM, R0

; Dummy read.

FSET

; Enable interrupts.

Example 3:

INT_SWITCH3:

PUSHC

FLG

; Push Flag register onto stack

FCLR

; Disable interrupts.

AND.B

#00h, 0055h

; Clear TA0IC int. priority level and int. request bit.

POPC

FLG

; Enable interrupts.

The reason why two NOP instructions or dummy read are inserted before FSET I in Examples 1 and

2 is to prevent the interrupt enable flag I from being set before the interrupt control register is rewritten

due to effects of the instruction queue.

If changing the interrupt control register using an instruction other than the instructions listed hear, and

if an interrupt occurs associated with this register during execution of the instruction, there can be

instances in which the interrupt request bit is not set. To avoid this problem, use one of the instruc-

tions given below to change the register.

Following instructions: AND, OR, BCLR or BSET

M30201 Datasheet(PDF) 49 Page - Renesas Technology Corp

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