I’m wanting to use Spark to detect a voltage reading from an alarm system. The alarm will put out 12 volts via its spec and when I put on a volt meter, around 13.95 for a period of 3 seconds, and then goes back to zero.
I’ve put a voltage regulator (3.3V 250mA - L4931) in line to drop the voltage down below 3.3. When I test the voltage with a volt meter on the other side of the voltage regulator, it will consistently put out 1.16 for 3 seconds.
What I’m trying to do is in the loop(), detect when voltage shows up. When using analogRead() I continually get 1.6 to 1.7 volts and it won’t detect a reading.
How best should I approach this as it seems it should be a simple task.