adc interfacing

hi frnds :) !!!!!!! I have a question on adc. I have 11 bit adc interfaced with PIC. the ADc i/p varies between 0v - 5v For 11 bit adc I have corresponding voltage values in hex chart . My basic question is that if some hysteresys occur between 2-3 values what should be the standard coding for adjusting that readings? for ex. if I have load-cell input of 100 kg. but my adc reads it either 98.5 or 100.5 :o how will I get the correct 100 ? :-/

Hi nayna,

Is the error always 1 or 2 bits as read from your ADC, or after conversion to floating point, or is it 2 percent of the actual reading? If its not a percent then you can hide the fluctuation by rounding off or displaying the nearest even (or odd) number.

You could also take a moving average of the readings and display that. There is a tutorial on data smoothing here: http://www.arduino.cc/en/Tutorial/Smoothing

Brave man for admitting that you are using a pic , what no helpful people on the pic forums ;)

Hey,

You are using a load cell for measuring forces correct? Are you sure it's the ADC that's having hysteresis or is it the strain gauge in the load cell? I would bet it's the load cell. If I recall correctly all strain gauges have some sort of hysteresis, if you read the documentation it might tell you what it is.

I'm not sure if there's anything you can do about this, apart from just taking an average between you readings around the hysteresis point. Or buy a load cell with less hysteresis?

Cheers, -Z-