Raspberry Pi - Potentiometer Servo Motor

This tutorial instructs you how to use Raspberry Pi to control the angle of a servo motor based on the input value from a potentiometer. In detail, we will learn:

Hardware Preparation

1×Raspberry Pi 4 Model B
1×Servo Motor
1×ADS1115 ADC Module
1×Jumper Wires
1×(Optional) Screw Terminal Adapter for Raspberry Pi

Or you can buy the following sensor kit:

1×DIYables Sensor Kit 30 types, 69 units
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Overview of Servo Motor and Potentiometer

If you are unfamiliar with servo motors and potentiometers (pinouts, how they work, how to program them, etc.), the following tutorials can help:

Wiring Diagram

The wiring diagram between Raspberry Pi and Servo Motor Potentiometer

This image is created using Fritzing. Click to enlarge image

Raspberry Pi Code

Detailed Instructions

  • Make sure you have Raspbian or any other Raspberry Pi compatible operating system installed on your Pi.
  • Make sure your Raspberry Pi is connected to the same local network as your PC.
  • Make sure your Raspberry Pi is connected to the internet if you need to install some libraries.
  • If this is the first time you use Raspberry Pi, See how to set up the Raspberry Pi
  • Connect your PC to the Raspberry Pi via SSH using the built-in SSH client on Linux and macOS or PuTTY on Windows. See to how connect your PC to Raspberry Pi via SSH.
  • Make sure you have the RPi.GPIO library installed. If not, install it using the following command:
sudo apt-get update sudo apt-get install python3-rpi.gpio
  • Install the Adafruit_ADS1x15 library by running the following commands on your Raspberry Pi terminal:
sudo pip install Adafruit-ADS1x15
  • Create a Python script file potentiometer_servo.py and add the following code:
# This Raspberry Pi code was developed by newbiely.com # This Raspberry Pi code is made available for public use without any restriction # For comprehensive instructions and wiring diagrams, please visit: # https://newbiely.com/tutorials/raspberry-pi/raspberry-pi-potentiometer-servo-motor import time import RPi.GPIO as GPIO import Adafruit_ADS1x15 # Constants SERVO_PIN = 26 # Raspberry Pi GPIO pin connected to the servo motor ADC_CHANNEL = 0 # Analog channel on ADS1015 GAIN = 1 # Gain (1, 2/3, 1, 2, 4, 8, 16) # Setup GPIO GPIO.setmode(GPIO.BCM) GPIO.setup(SERVO_PIN, GPIO.OUT) # Create PWM instance for servo servo_pwm = GPIO.PWM(SERVO_PIN, 50) # 50 Hz frequency servo_pwm.start(0) # Initialize servo position # Create ADS1x15 instance ads = Adafruit_ADS1x15.ADS1015() def map_value(value, in_min, in_max, out_min, out_max): # Map the input value from one range to another return (value - in_min) * (out_max - out_min) / (in_max - in_min) + out_min try: while True: # Read the raw ADC value from the potentiometer pot_value = ads.read_adc(ADC_CHANNEL, gain=GAIN) # Map the ADC value to the servo angle (0 to 180 degrees) angle = int(map_value(pot_value, 0, 32767, 0, 180)) # Control the servo motor according to the angle duty_cycle = (angle / 18) + 2.5 # Convert angle to duty cycle servo_pwm.ChangeDutyCycle(duty_cycle) print(f"Potentiometer Value: {pot_value}, Servo Angle: {angle}") time.sleep(0.1) except KeyboardInterrupt: servo_pwm.stop() GPIO.cleanup()
  • Save the file and run the Python script by executing the following command in the terminal:
python3 potentiometer_servo.py

The script runs in an infinite loop continuously until you press Ctrl + C in the terminal.

  • Turn the potentiometer
  • Check out the servo motor's rotation
  • View the outcome in the Serial Monitor
PuTTY - Raspberry Pi
Potentiometer Value: 100, Servo Angle: 3 Potentiometer Value: 200, Servo Angle: 6 Potentiometer Value: 300, Servo Angle: 9 Potentiometer Value: 400, Servo Angle: 13 Potentiometer Value: 500, Servo Angle: 16 Potentiometer Value: 600, Servo Angle: 19 Potentiometer Value: 700, Servo Angle: 23 Potentiometer Value: 800, Servo Angle: 26 Potentiometer Value: 900, Servo Angle: 29 Potentiometer Value: 1000, Servo Angle: 33

Code Explanation

Check out the line-by-line explanation contained in the comments of the source code!

Video Tutorial