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CHAPTER 24 STANDBY FUNCTION
User’s Manual U12697EJ3V0UM
(1) Released by a non-maskable interrupt
When a non-maskable interrupt is generated, the halt mode is released regardless of the enable state (EI) and
disable state (DI) for interrupt acknowledgement.
If the non-maskable interrupt that released the HALT mode can be acknowledged when released from the HALT
mode, that non-maskable interrupt is acknowledged, and execution branches to the service program. If it cannot
be acknowledged, the instruction following the instruction that set the HALT mode (MOV STBC, #byte instruction)
is executed. The non-maskable interrupt that released the HALT mode is acknowledged when acknowledgement
is possible. For details about non-maskable interrupt acknowledgement, refer to
22.6 Non-Maskable Interrupt
Acknowledgment Operation
.
Caution The HALT mode cannot be released with the watchdog timer.
(2) Released by a maskable interrupt request
The HALT mode released by a maskable interrupt request can only be released by an interrupt where the interrupt
mask flag is 0.
If an interrupt can be acknowledged when the halt mode is released and the interrupt request enable flag (IE)
is set to 1, execution branches to the interrupt service program. If the IE flag is cleared to 0 when acknowledgement
is not possible, execution restarts from the next instruction that sets the HALT mode. For details about interrupt
acknowledgement, refer to
22.7 Maskable Interrupt Acknowledgment Operation
.
A macro service temporarily releases the HALT mode, performs the one-time processing, and returns again to
the HALT mode. If the macro service is only specified several times, the HALT mode is released when the VCIE
bit in the macro service mode register in the macro service control word is cleared to 0.
The operation after this release is identical to the release by the maskable interrupt described earlier. Also when
the VCIE bit is set to 1, the HALT mode is entered again, and the HALT mode is released by the next interrupt
request.
