External Interrupt Request Input Pins (Nmi, Intp0 To Intp7); Noise Elimination - NEC V850ES/KE1+ User Manual

CHAPTER 17 INTERRUPT/EXCEPTION PROCESSING FUNCTION

17.4 External Interrupt Request Input Pins (NMI, INTP0 to INTP7)

17.4.1 Noise elimination

(1) Noise elimination for NMI pin
The NMI pin includes a noise eliminator that operates using analog delay. Therefore, a signal input to the NMI
pin is not detected as an edge unless it maintains its input level for a certain period. The edge is detected only
after a certain period has elapsed.
The NMI pin is used for releasing the STOP mode. In the STOP mode, noise elimination using the system
clock is not performed because the internal system clock is stopped.
(2) Noise elimination for INTP0 to INTP2 and INTP4 to INTP7 pins
The INTP0 to INTP2 and INTP4 to INTP7 pins include a noise eliminator that operates using analog delay.
Therefore, a signal input to each pin is not detected as an edge unless it maintains its input level for a certain
period. The edge is detected only after a certain period has elapsed.
(3) Noise elimination for INTP3 pin
The INTP3 pin has a digital/analog noise eliminator that can be selected by the NFC.NFEN bit.
The number of times the digital noise eliminator samples signals can be selected by the NFC.NFSTS bit from
three or two. The sampling clock can be selected by the NFC.NFC2 to NFC.NFC0 bits from f
f /256, f /512, f /1024, and f
XX XX XX
the sampling clock stops in the IDLE/STOP mode. It cannot therefore be used to release the standby mode.
To release the standby mode, select f
. If the sampling clock is set to f
XT
as the sampling clock or select the analog noise eliminator.
XT
User's Manual U16896EJ2V0UD
/64, f /128, f /256, f /512, or f
XX XX XX XX
/64, f /128,
XX XX
/1024,
XX
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