NEC V850E/IA1 mPD703116 User Manual page 223

(2) Release of software STOP mode
Software STOP mode is released by a non-maskable interrupt request, an unmasked maskable interrupt
Note
request (INTPn) , or RESET pin input. Also, to release software STOP mode when PLL mode (CKSEL pin
= low level) and resonator connection mode (CESEL bit of CKC register = 0) are used, the oscillator's
oscillation stabilization time must be secured (n = 0 to 6, 20 to 25).
Moreover, PLL lockup time may be required depending on the program. See 8.4 PLL Lockup for details.
Note When a digital filter using clock sampling is selected as the noise eliminator for INTP20 to INTP25, the
software STOP mode cannot be released.
(a) Release by a non-maskable interrupt request or an unmasked maskable interrupt request
The software STOP mode can be released by an interrupt request only when transition to software STOP
mode is performed with the INTM and NMIM bits of the PSC register set to 0.
Software STOP mode is released by a non-maskable interrupt request or by an unmasked maskable
interrupt request (INTPn) regardless of the priority. However, if the system is set to software STOP
mode during a maskable interrupt servicing routine, operation will differ as follows (n = 0 to 6, 20 to 25).
(i) If an interrupt request is generated with a lower priority than that of the interrupt request that is
currently being serviced, software STOP mode is released, but the newly generated interrupt request
is not acknowledged. The new interrupt request is held pending.
(ii) If an interrupt request (including non-maskable interrupt requests) is generated with a higher priority
than that of the interrupt request that is currently being serviced, software STOP mode is released
and the newly generated interrupt request is acknowledged.
Table 8-7. Operation After Software STOP Mode Is Released by Interrupt Request
Release Source
Non-maskable interrupt request
Maskable interrupt request
If the system is set to software STOP mode during an NMI servicing routine, software STOP mode is
released, but the interrupt is not acknowledged (interrupt is held pending).
Interrupt servicing that is started when software STOP mode is released by NMI pin input is handled in
the same way as normal NMI interrupt servicing that occurs during an emergency (because the NMI
interrupt handler address is unique). Therefore, when a program must be able to distinguish between
these two situations, a software status must be prepared in advance and that status must be set before
setting the PSMR register using a store instruction or a bit manipulation instruction.
By checking for this status during NMI interrupt servicing, an ordinary NMI can be distinguished from the
servicing that is started when software STOP mode is released by NMI pin input.
(b) Release by RESET pin input
This is the same as a normal reset operation.
CHAPTER 8 CLOCK GENERATION FUNCTION
Enable Interrupt (EI) Status
Branch to handler address
Branch to handler address or
execute next instruction
User's Manual U14492EJ3V0UD
Disable Interrupt (DI) Status
Execute next instruction
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