D17133CS datasheet(173/289 Pages) NEC

173 / 289 page

CHAPTER 14

INTERRUPT FUNCTIONS

158

14.4 PROGRAM EXAMPLE OF INTERRUPT

• Program example of contermeasure for noise reduction of external interrupt (INT pin)

This example assumes the case of assigning INT pin for key input, etc.

When taking into the microcontroller data in kind of switch such as key input processing, it takes some time

for the level of input voltage to be stabilized after pushing the key or switch. Accordingly, the countermeasures

for removing the noise generated by key, etc. should be executed by software.

In the following program, after generating external interrupt, the signal from INT pin becomes effective after

confirming that there is not change in the level of INT pin two times in every 100

µs.

Example

WAITCNT

MEM

0.00H

; Counter of wait processing

KEYON

FLG

0.01H.3

; If key ON is determined (even just once), KEYON=1

SECOND

FLG

0.01H.0

; A flag describing key-checking for the second time.

ORG

JOB_INIT

ORG

INT_JOB

JOB_INIT:

MOV

WAITCNT, #0

; Clears RAM and the flag on RAM

CLR2

KEYON, SECOND ;

INITFLG

NOT IEGMD1, IEGMD0

; Rising edge is effective for the interrupt from INT pin

CLR1

IRQ

SET1

MAIN:

CALL

××JOB

; arbitrary processing

CALL

××JOB

; arbitrary processing

MAIN

D17133CS Datasheet(PDF) 173 Page - NEC

D17133CS Datasheet(HTML) 173 Page - NEC

Html Pages

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 ...More

Datasheet Download

Link URL