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CHAPTER 18 STANDBY FUNCTION
18.5.2 IDLE Mode Release
IDLE mode is released by NMI input, or RESET input.
Table 18-6. IDLE Mode Release and Operations after Release
Release
Source
State after Release
Operation after Release
NMI pin input
Non-maskable interrupt service
program not being executed
Low-priority non-maskable interrupt
service program being executed
Interrupt request acknowledgment
NMI pin input service program being
executed
High-priority non-maskable interrupt
service program being executed
Execution of instruction after MOV STBC/
#byte instruction (interrupt request that
released IDLE mode is held pending
Note
)
RESET input
—
Normal reset operation
Note
Pending interrupt requests are acknowledged when acknowledgment becomes possible.
(1) IDLE mode release by NMI input
IDLE mode is released when the valid edge specified by external interrupt mode register 0 (INTM0) is input to the
NMI input.
When the
m
PD784046 is released from IDLE mode, if a non-maskable interrupt by NMI pin input can be
acknowledged, a branch is made to the NMI interrupt service program. If the interrupt cannot be acknowledged (if
the IDLE mode is set in an NMI interrupt service program, etc.), execution is resumed from the instruction following
the instruction that set the IDLE mode, and a branch is made to the NMI interrupt service program when
acknowledgment becomes possible (by execution of an RETI instruction, etc.).
Refer to
16.6 Non-Maskable Interrupt Acknowledgment Operation
for details of NMI interrupt acknowledgment.
(2) IDLE mode release by RESET input
Normal operation is started when RESET rises after RESET input falls from high to low.
Unlike an ordinary reset operation, data memory retains its contents prior to IDLE mode setting.
Caution When the execution of the IDLE mode instruction contends with the interrupt of release source
of the IDLE mode, the STOP mode is released after the STOP mode has been executed, instead
of the normal operation where the IDLE mode is released after the IDLE mode has been executed,
because of a malfunction of the
m
PD784054. Therefore, when the IDLE mode is released, the wait
operation for the oscillation stabilization time set by the oscillation stabilization time specification
register (OSTS) may be executed even though the IDLE mode is set in software (Usually, the
m
PD784054 does not wait the oscillation stabilization time when the IDLE mode is released.) If there
are problems with waiting for the oscillation stabilization time when the IDLE mode is released,
set the value of the oscillation stabilization time set by the OSTS as short as possible.