Rotary Potentiometer

Changes its electrical resistance based on its rotation angle. Can detect rotation angles between 0° and 270°.

Learn how to make your own rotary potentiometer here.

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Background

What is a Potentiometer?

Potentiometers are a type of variable resistor consisting of a resistive track with electrical contacts at both ends. Like a fixed-value resistor, potentiometers have a fixed resistance value between both ends (for example, 10 kΩ.) A third, movable contact is located between both ends. This contact (called wiper) allows us to achieve a variable resistance by flowing electricity through a shorter portion of the resistive track.

Basic Usage

# --- Imports
import time
import board
import analogio

# --- Variables
# Initialize analog input connected to rotation potentiometer
potentiometer = analogio.AnalogIn(board.A2)

# --- Functions

# --- Setup

# --- Main loop
while True:
    val = potentiometer.value # Read the potentiometer value
    print(val) # Output the value in the serial monitor
    time.sleep(0.05)  # Make the loop run a little bit slower

Rotation potentiometer example with conversion to voltage

# --- Imports
import time
import board
import analogio

# --- Variables
# Initialize analog input connected to rotation potentiometer
potentiometer = analogio.AnalogIn(board.A2)

# --- Functions
# Make a function to convert from analog value to voltage.
def analog_voltage(adc):
    return adc.value / 65535 * adc.reference_voltage

# --- Setup

# --- Main loop
while True:
    val = potentiometer.value # Read the photo resistor value
    volts = analog_voltage(potentiometer) # Convert to voltage

    # Print the values
    print('Photo resistor value: {0} voltage: {1}V'.format(val, volts))
    time.sleep(0.05)  # Make the loop run a little bit slower

Rotation potentiometer example with angle mapping

# --- Imports
import time
import board
import analogio

# --- Variables
# Initialize analog input connected to rotation potentiometer
potentiometer = analogio.AnalogIn(board.A2)

# --- Functions
# Make a function to convert from analog value to 270 degrees
def get_angle(adc):
    return adc.value / 65535 * 270

# --- Setup

# --- Main loop
while True:
    val = potentiometer.value # Read the photo resistor value
    angle = get_angle(potentiometer) # Convert to voltage

    # Print the values
    print('Potentiometer value: {0} Angle: {1}º'.format(val, angle))
    time.sleep(0.05)  # Make the loop run a little bit slower