M32CSLASH8A datasheet(113/372 Pages) RENESAS

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M32C/8A Group

11. Interrupts

Rev.1.00

Jul 15, 2007

Page 96 of 352

REJ09B0385-0100

11.2

Software Interrupts

Software interrupts occur when particular instructions are executed. Software interrupts are non-maskable.

11.2.1

Undefined Instruction Interrupt

The undefined instruction interrupt occurs when the UND instruction is executed.

11.2.2

Overflow Interrupt

The overflow interrupt occurs when the INTO instruction is executed while the O flag in the FLG register is 1

(arithmetic operation overflow). Instructions that can set the O flag are: ABS, ADC, ADCF, ADD, ADDX,

CMP, CMPX, DIV, DIVU, DIVX, NEG, RMPA, SBB, SCMPU, SHA, SUB, SUBX

11.2.3

BRK Interrupt

The BRK interrupt occurs when the BRK instruction is executed.

11.2.4

BRK2 Interrupt

The BRK2 interrupt occurs when the BRK2 instruction is executed.

Do not use this interrupt. This is for use with development support tool only.

11.2.5

INT Instruction Interrupt

The INT instruction interrupt occurs when the INT instruction is executed. The INT instruction can specify

software interrupt numbers 0 to 63. Software interrupt numbers 8 to 43 are assigned to the vector table used for

the peripheral function interrupt. This means that the MCU is able to execute the peripheral function interrupt

routine by executing the INT instruction. When the INT instruction is executed, values in the FLG register and

PC are saved to the stack. The relocatable vector of the specified software interrupt number is stored in PC.

The stack, where the data is saved, varies depending on a software interrupt number.

ISP is selected for software interrupt numbers 0 to 31. (The U flag in the FLG register becomes 0.) For

software interrupt numbers 32 to 63, SP which is selected immediately before executing the INT instruction is

used. (The U flag does not change.)

For the peripheral function interrupt, the FLG register value is saved and the U flag becomes 0 (ISP selected)

when an interrupt request is acknowledged. Therefore, for software interrupt numbers 32 to 43, SP to be used

can differ depending on whether an interrupt is generated by a peripheral function or by the INT instruction.

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