How to Use Servo: Examples, Pinouts, and Specs

A servo is a rotary actuator that allows for precise control of angular position, velocity, and acceleration. It consists of a motor coupled to a sensor for position feedback, along with a control circuit. Servos are widely used in robotics, automation, remote-controlled vehicles, and other applications requiring precise movement and positioning.

• Robotics: For controlling robotic arms, grippers, and joints.
• Remote-controlled vehicles: Steering mechanisms and throttle control.
• Automation: Conveyor belts, sorting systems, and industrial machinery.
• Hobby projects: Model airplanes, boats, and cars.
• Camera gimbals: For stabilizing and positioning cameras.

Below are the general technical specifications for a standard hobby servo. Note that specifications may vary depending on the specific model and manufacturer.

Servos typically have three wires for connection. The pinout is as follows:

1. Power the Servo: Connect the red wire to a 5V or 6V power source and the black/brown wire to ground.
2. Control Signal: Connect the yellow/orange wire to a PWM-capable pin on your microcontroller (e.g., Arduino).
3. Generate PWM Signal: Use a PWM signal to control the servo's position. A pulse width of 1ms typically moves the servo to 0°, 1.5ms to 90°, and 2ms to 180°.

• Power Supply: Ensure the power supply can handle the servo's stall current to avoid voltage drops.
• Decoupling Capacitor: Add a capacitor (e.g., 100µF) across the power supply to stabilize voltage.
• Avoid Overloading: Do not exceed the servo's torque rating to prevent damage.
• PWM Frequency: Use a PWM frequency of 50Hz (20ms period) for standard servos.
• Mechanical Limits: Avoid forcing the servo beyond its physical limits to prevent damage.

Below is an example code to control a servo using an Arduino UNO:

#include <Servo.h> // Include the Servo library

Servo myServo; // Create a Servo object

void setup() {
  myServo.attach(9); // Attach the servo to pin 9
}

void loop() {
  myServo.write(0); // Move servo to 0 degrees
  delay(1000);      // Wait for 1 second

  myServo.write(90); // Move servo to 90 degrees
  delay(1000);       // Wait for 1 second

  myServo.write(180); // Move servo to 180 degrees
  delay(1000);        // Wait for 1 second
}

• The Servo library simplifies servo control.
• The attach() function links the servo to a specific PWM pin.
• The write() function sets the servo's position in degrees (0° to 180°).
• Delays are used to allow the servo to reach the desired position.

1. Servo Not Moving

   • Cause: Incorrect wiring or insufficient power supply.
   • Solution: Double-check connections and ensure the power supply meets the servo's requirements.

2. Jittery Movement

   • Cause: Electrical noise or unstable power supply.
   • Solution: Add a decoupling capacitor across the power supply and ensure proper grounding.

3. Overheating

   • Cause: Prolonged stalling or overloading.
   • Solution: Avoid exceeding the servo's torque rating and ensure it is not mechanically blocked.

4. Limited Range of Motion

   • Cause: PWM signal out of range or mechanical limits.
   • Solution: Verify the PWM signal range (1ms to 2ms) and ensure the servo is not obstructed.

Q: Can I power a servo directly from the Arduino?
A: It is not recommended, as the Arduino's 5V pin cannot supply enough current for most servos. Use an external power supply.

Q: How do I control multiple servos with an Arduino?
A: Use the Servo library to create multiple Servo objects and attach each to a different PWM pin.

Q: Can I rotate a servo continuously?
A: Standard servos have a limited range (0° to 180°). For continuous rotation, use a continuous rotation servo.

Q: What happens if I send a PWM signal outside the 1ms to 2ms range?
A: The servo may attempt to move beyond its physical limits, potentially causing damage. Always stay within the specified range.