I am voltage dividing 0 to 64 VDC down to 0 to 1.8 volts via a simple voltage divider.
I am using 1% resistors.
The problem is that the readings from the ADC in my beaglebone black seems to be drifting over time in that say 48 volts is not consistently reported as the same ADC reading day to day.
The attached chart shows the drift. Each day should look identical and does via a Fluke meter.
My circuit is
Vin -> 4700ohm -> 120ohm -> gnd
The ADC sense pin attaches between the 4700ohm and the 120ohm resistors. The ADC reference gnd is attached to gnd.
The +5vdc power supply that supplies the microprocessor and ADC is isolated from the above circuit except for a common gnd.
Should I expect so much drift via the voltage divider (presumedly due to temperature)?