System Break Interrupt (Sbi) - Mitsubishi Electric M32R Series User Manual

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4.9.2 System Break Interrupt (SBI)

System Break Interrupt (SBI) is an emergency interrupt which is used when power outage is
detected or a fault condition is notified by an external watchdog timer. The system break interrupt
cannot be masked by the PSW register IE bit. Therefore, the system break interrupt can only be
used when some fatal event has already occurred to the system when the interrupt is detected.
Also, this interrupt must be used on condition that after processing by the SBI handler, control will
not return to the program that was being executed when the system break interrupt occurred.
[Occurrence Conditions]
A system break interrupt is accepted by a falling edge on SBI input pin. (The system break
interrupt cannot be masked by the PSW register IE bit.)
In no case will a system break interrupt be activated immediately after executing a 16-bit
instruction that starts from a word boundary. (For 16-bit branch instructions, however, the
interrupt may be accepted immediately after branching.)
Address 1000
16-bit instruction
Interrupt may
be accepted
Figure 4.9.1 Timing at Which System Break Interrupt (SBI) is Accepted
Order in which instructions are executed
Address 1002 Address 1004
16-bit instruction
Interrupt Interrupt may
cannot be be accepted
accepted
4-16
4.9 Interrupt Processing
_______
32-bit instruction
Interrupt may
be accepted
EIT
Address 1008
Ver.0.10