filtering - RC Filter at the ADC input pins of beagle bone black -


i trying read thermistor beagle bone black.

i have voltage divider circuit feeds unity gain opamp. o/p of opamp connected simple rc low pass filter feeds voltage adc pin.

the problem have noticed voltage sensed beagle bone 0.02v higher actual voltage @ opamp output.

at first thought software issue, on further investigation found out voltage @ adc pin raised 0.02v. if feed adc pin directly opamp, without rc filter not have issue. has else experienced similar?

thanks in advance!

the resistance in rc filter high causing voltage drop because of internal impedance of adc pin. can use active low pass filter resolve problem: http://en.wikipedia.org/wiki/low-pass_filter#active_electronic_realization


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