# What are the units of a potentiometer?

I had a teacher ask what the units were for a potentiometer and I did not know.

The potentiometer is a variable resistance device but one it gets processed by Robot C is it still resistance or is it a voltage drop?

0 - 4095 makes it seem like the voltage drop in millivolts from 5 volts going in. But 4k is so much of a perfect computer sized holder of bits that it makes me think it is just a mapped value from something else. So what units would it be?

My guess it maps that voltage drop to a value in bits. That’s a 12 bit resolution we have there with 4095. Definitely something interesting to look up though.

I’m no expert but I’m guessing 0 to 4095 is just the range you happen to get out of 12 bits. It’s 2^12. The pots are about 10 Kohm, so you could, if you want, scale the 0-4095 to convert to ohms or to millivolts. The pot raw “units” are not really anything by themselves but could be converted to mean whatever you want - millivolts coming back to the Cortex ADC, angles of an arm, etc.

OscarNVCC is correct. A potentiometer is essentially a variable resistor that changes it’s resistance with the rotation of the shaft. This change in resistance causes a change in voltage that can be measured by the microcontroller. The microcontroller then uses an analog to digitial (A/D) converter to turn the analog signal into a digital signal that is used by the the robot’s programming.

-Charles