UPD784938 Datasheet, PDF (649/733 Pages) NEC – 16-Bit Single-Chip Microcontrollers

CHAPTER 25 STANDBY FUNCTION
(2) STOP mode release by INTP4 or INTP5 input
When masking of interrupts by INTP4 and INTP5 input is released and macro service is disabled, the oscillator resumes
oscillation when the valid edge specified by external interrupt mode register 1 (INTM1) is input to the INTP4 or INTP5
input. Following this, STOP mode is released after the oscillation stabilization time specified by the oscillation
stabilization time specification register (OSTS) elapses.
When the µPD784938 is released from STOP mode, if an interrupt can be acknowledged when the interrupt enable
flag (IE) is set (to 1), a branch is made to the interrupt service program. If the interrupt cannot be acknowledged and
if the IE flag is cleared (to 0), execution is resumed from the instruction following the instruction that set the STOP mode.
See 23.7 Maskable Interrupt Acknowledgment Operation for details of interrupt acknowledgment.
Figure 25-6. STOP Mode Release by INTP4/INTP5 Input
STOP
Oscillator
fXX/2
STP F/F1
STP F/F2
INTP4, INTP5 input
Rising edge
specified
Oscillation stopped
Oscillation stabilization
count time
(3) STOP mode release by RESET input
When RESET input falls from high to low and the reset state is established, the oscillator resumes oscillation. The
oscillation stabilization time should be secured while RESET is active. Thereafter, normal operation is started when
RESET rises.
Unlike an ordinary reset operation, data memory retains its contents prior to STOP mode setting.
Preliminary User’s Manual U13987EJ1V0UM00
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