Reading 2 seperate batterys A2D?

Thread Starter


Joined Jan 14, 2011
Hi forum, Voodoo the bot builder here again.

I am using pic18f4550 with 3.5v battery .I am using an A2D port & took the vref off the output of the switching regulator @5v & all working fine. I took the vref ext off the regulator as the voltage stays constant. What I'm stuck with is ;
I have 2 batterys the same lipo 3.5v. One for the micro & the other for the motors. the motor regulator runs @ 6.5v & I cannot read both batterys using A2D cos I get a conflict from the vref cos its a seperate battery. Apart for building a circuit I cannot see a way around this. I would prefer to read both batterys A2D.
Last edited:


Joined Jul 18, 2011
Hi. Can you post a schematic of your circuit? Are you trying to read a "floating" battery signal on your ground-referenced MPU?