Potentiometer for arduino, what resistance do you need?

Question

Arduino

Good day, please treat my noob question with patience)
In physics / robotics, a layman, I try to master everything gradually The
question is this: I
connected a potentiometer (at 100 ohms) to Leonardo's arduino , but it does not read any readings from it, is there a difference on how many ohms does it have resistance, or does it not matter?
The buttons / switches work correctly, but there are no signs from the potentiometers (
How to figure out what is not working, and what can you suggest to study this issue in more detail (what does the resistance of the potentiometer affect when connected to an arduino, which one is needed, etc.)
Thank you very much in advance)

Answer 1

In this case, the Arduino is a voltmeter, and with a sufficiently large input resistance.
This means that the choice of potentiometer resistance is dictated by the current that will flow through it in the first place. 100 ohm will also work (if connected and programmed correctly), but it will have quite a lot of current flowing through it (5V / 100 ohm = 0.05A = 50 milliamps), which can be a problem if the device is battery powered - batteries will be fast sit down.
Typical choices are 10,000 to 100,000 ohm potentiometers.
The best way to test a potentiometer is to measure the voltage at the output of the motor with a multimeter when the ends of the resistance are connected to a power source with a known output voltage. At the same time, it is desirable to have a multimeter with a pointer in order to assess the smoothness of operation and the absence of areas with poor contact between the slider and the track.

Answer 2

The potentiometer should be used as a " voltage divider ". We connect the leg from the " engine
" of the potentiometer to the Arduino analog input (usually the middle contact). We connect the extreme legs, respectively, to the " ground " and " Power ". The analogRead () command reads the value of the analog input. Given a value of 100 ohms, with a 5V supply, the current through the resistor will be approximately 0.5A. The power supply may not appreciate this approach. Therefore, as a rule, variable resistors are used in the range of 1KΩ - 100KΩ. We will not consider the option with "pull-up resistors", a simple measurement of the voltage at the analog input is enough to start.