Thank for you tips. Using the millis - time to check if a double press is being done... OK I think I get you. To impliment in my code, that I will figure this out. It look like it is a good idea. I will impliment something like that.
Let see :Loop 1 : read key Loop 1 ---> I mean : void loop()
measured time
Loop 2 : readkey
measured time
check the time difference
if to small - don't take the key
if big enough - take the key
Something like that. But with a 555 in monostable - output of the 555 going to the interrupt pin will solve the debouncing problem.
And I will do a digitalWrite( latchkeypin, HIGH ) in the interrupt routine to latch the keypad data.
@NI$HANT
To monitor the interrupt routine using Serial Monitor is a good idea.
also. Mr.Serje you told once that amplifying(if i recall it right from my memory) the keypad buttons may make then susceptible to ultra sensitivity and thus the same can result in debounce
I agree. That the 555 in monostable come in. I just set the output of the 555 about .. let say 10 mS to 20 mS. The input can multi pulse for 1 ms to 8 mS until it is stable, and the 555 chip won't even care about it. It is after the 555 finish it's pulse that the 555 chip care. ( the mono stable circuit, that is )