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:
- How to connect the potentiometer and servo motor to Raspberry Pi
- How to program Raspberry Pi to read the value from a potentiometer and control a servo motor accordingly.
Hardware Preparation
| 1 | × | Raspberry Pi 4 Model B | |
| 1 | × | Servo Motor | |
| 1 | × | Potentiometer | |
| 1 | × | ADS1115 ADC Module | |
| 1 | × | Breadboard | |
| 1 | × | Jumper Wires | |
| 1 | × | (Optional) Screw Terminal Adapter for Raspberry Pi |
Or you can buy the following sensor kits:
| 1 | × | DIYables Sensor Kit (30 sensors/displays) | |
| 1 | × | DIYables Sensor Kit (18 sensors/displays) |
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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
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!