UPD784938 Datasheet, PDF (648/733 Pages) NEC – 16-Bit Single-Chip Microcontrollers

CHAPTER 25 STANDBY FUNCTION
(1) STOP mode release by NMI input
The oscillator resumes oscillation when the valid edge specified by external interrupt mode register 0 (INTM0) is input
to the NMI input. STOP mode is released after the oscillation stabilization time specified by the oscillation stabilization
time specification register (OSTS).
When the µPD784938 is released from STOP 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 STOP mode
is set in an NMI interrupt service program, etc.), execution is resumed from the instruction following the instruction that
set the STOP mode, and a branch is made to the NMI interrupt service program when acknowledgment becomes
possible (by execution of an RETI instruction, etc.).
See 23.6 Non-maskable Interrupt Acknowledgment Operation for details of NMI interrupt acknowledgment.
Figure 25-5. STOP Mode Release by NMI Input
STOP
Oscillator
fXX/2
STP F/F1
STP F/F2
NMI input
Rising edge
specified
Oscillator stopped
Oscillation stabilization
count time
648
Preliminary User’s Manual U13987EJ1V0UM00