Is it OK if I use 100K linear potentiometers to input values to Arduino?
The documentation specifies 10K should be used and I suppose that would translate to 0.5mA power consumption which would be well within spec of maximal 40mA per pin.
The question is, would it be fine to use 1K or 100K potentiometers because that should translate to 5mA and 0.05mA power consumption?
What is the advantage/disadvantage of using higher or lower value potentiometers?
What are the upper/lower values pots which are OK to use?
Best Answer
As @Brian Drummond suggested, when you set the pins to input mode, they have high impedance, so they're not going to sink much current no matter how the external resistors are set up. The data sheet suggests using 10k or less because if you use a higher value than that, you'll need to increase the sample time of the ADC. The ADC works by allowing current from the input to charge a capacitor, then holding the the charge in the capacitor and using it as the input to a comparator. The ADC repeatedly generates candidate values and compares them with the capacitor charge until it finds the closest match; that value becomes the ADC output. If the impedance of the analog source is greater than 10k, the capacitor won't fully charge, and you'll get incorrect readings. You can increase the sample time, but that will decrease your sampling resolution (you'll get fewer samples per second). I don't think there's much reason to use a 100k pot over a 10k unless 100k is all you have.