Need help with voltage counter

Question

I have a system that passes current through a resistor when ever a button is pushed.  The voltage across the resistor (about 100mV) is read by a cFP-AI-102 Analog Input voltage module.  I'm trying to figure out a way to count the number of times this happens.  In other words, I need to count how many times the button is pushed.
I've tried using a While Loop, but since it counts with every iteration I end up with way too many counts for each button push.  Is there a way I only count once?
Thanks,
Eric

Answer 1

Hi!
   If I understand, you want to measure how many times button is pushed, i.e. how many transition 0 -> 100 mV, right?  I'd do that with a shift register and a while loop.... just save the past state of the analog in, if the comparison between the past state and curtrent state is > 50 mV, you have a push.... (actually it depends on how terminals are connected...)
 Post your code, perhaps I can understand better the starting point. 
   remember: this way you're going to measure too many transitions, because usually, when a button is pressed or released you have some oscillating voltage (I don't know if you ever tried to handle a switch button with a microcontroller, there you can see this).  But maybe, AI module sample at "low frequencies" respect to this phenomenon.
graziano