M30622SAFP MITSUBISHI [Mitsubishi Electric Semiconductor], M30622SAFP Datasheet - Page 45

• Manufacturer Part Number: M30622SAFP
• Description: SINGLE-CHIP 16-BIT CMOS MICROCOMPUTER
• Manufacturer: MITSUBISHI [Mitsubishi Electric Semiconductor]

Interrupt
Software Interrupts
A software interrupt occurs when executing certain instructions. Software interrupts are non-maskable
interrupts.
• Undefined instruction interrupt
• Overflow interrupt
• BRK interrupt
• INT interrupt
An undefined instruction interrupt occurs when executing the UND instruction.
An overflow interrupt occurs when executing the INTO instruction with the overflow flag (O flag) set to
“1”. The following are instructions whose O flag changes by arithmetic:
ABS, ADC, ADCF, ADD, CMP, DIV, DIVU, DIVX, NEG, RMPA, SBB, SHA, SUB
A BRK interrupt occurs when executing the BRK instruction.
An INT interrupt occurs when specifying one of software interrupt numbers 0 through 63 and execut-
ing the INT instruction. Software interrupt numbers 0 through 31 are assigned to peripheral I/O inter-
rupts, so executing the INT instruction allows executing the same interrupt routine that a peripheral I/
O interrupt does.
The stack pointer (SP) used for the INT interrupt is dependent on which software interrupt number is
involved.
So far as software interrupt numbers 0 through 31 are concerned, the microcomputer saves the stack
pointer assignment flag (U flag) when it accepts an interrupt request. If change the U flag to “0” and
select the interrupt stack pointer (ISP), and then execute an interrupt sequence. When returning from
the interrupt routine, the U flag is returned to the state it was before the acceptance of interrupt re-
quest. So far as software numbers 32 through 63 are concerned, the stack pointer does not make a
shift.
SINGLE-CHIP 16-BIT CMOS MICROCOMPUTER
M16C / 62A Group
Mitsubishi microcomputers
45