Hiya,
Im using a PIC24 and need to measure the voltage across a battery as well as the current into it.
The voltage across the battery is done, A/D input at +ve, PIC ground to negative. The problem comes when trying to measure current in, for which I plan to measure the voltage drop across a low value resistor.
As far as I can figure, my PIC will only measure positive voltage differences.
If I connect the resistor in series with the battery and try to measure the voltage across it, the placement of wires will effectively connect one of the A/D inputs of the battery voltmeter to the PIC ground of the resistor voltmeter and vice-versa.
Is there any way the pic will measure negative voltages so i can swap the polarity of the wires?
Any other suggestions?
Thanks.