I have searched for an hour before I posted, I promised. Please be kind ad this is my 2nd project in arduino.
Output device = Skylink HA-434RL motion detection receiver Input device = Arduino Nano v3.0
In a nutshell this output devices has 4x led's to represent zones of motion or alarm detection.
I have tapped (soldered) into one leg of each of the 4x LED's and also 1x opposite leg of #4 led (shared ground? tested via ohm meter).
My question is... What is the safest way to input each LED's status into my Arduino project.
1.) I have tried a multimeter with (-) on Arduino GND pin and Skylink LED#1 pin, result 0v 2.) I have tried a multimeter with (+) on Arduino GND pin and Skylink LED#1 pin, result 0v 3.) I have tried a multimeter with (-) on Skylink apparent shared ground and (+) on LED #1 with result 3.0v DC when LED flashes.
My question is... Can I use the following tutorial to leverage the following code to use the shared ground from Skylink as a ref ground?
analogReference(EXTERNAL); // use AREF for reference voltage
Thanks and please be patient with a newbie.