Arduino + ADC (ADS1211P) + coil and magnet. Everything works great, when i move a magnet near the coil, i get positive and negative numbers. Measuring the voltage using coil+magnet, i get a range from -0.1v to 0.1v (or 0.01v?).
Since the signal is so small, i wish to amplify it using a OP-AMP.
So i added a non-inverting op-amp (5V single supply), measuring the output of amp is around 0v-5v. When i connect to the ADC, the output of the amp goes to one input, the second input from the ADC goes to REF 2.5V from the ADC.
[u]The problem is: ADC only give positive numbers when moving the magnet near the coil.[/u]
When using Self calibrated mode in the ADC, the values start at 0 and goes up to +32000 (16bits). When not using calibration on the ADC the values start at -24000 and goes up to 32000.
I cant really understand where the problem is :cold_sweat:
Strange thing, i´m getting 1.6V in any input in the ADC?! I´m only using a breadboard, just wish to do some tests..not looking yet for accuracy in the ADC.