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 motion control. Their ability to move to a specific angle makes them ideal for tasks such as steering mechanisms, robotic arms, and camera gimbals.

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

• Operating Voltage: 4.8V to 6V (typical)
• Operating Current: 100mA to 1A (depending on load)
• Torque: 1.5 kg-cm to 25 kg-cm (varies by model)
• Rotation Range: 0° to 180° (standard), 360° for continuous rotation servos
• Control Signal: Pulse Width Modulation (PWM)
• Pulse Width Range: 1ms (0°) to 2ms (180°)
• Neutral Position: 1.5ms (90°)
• Frequency: 50Hz (typical)

Servos typically have three wires for connection. The table below describes the pin configuration:

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 signal wire to a PWM-capable pin on your microcontroller (e.g., Arduino).
3. PWM Signal: Generate a PWM signal with a frequency of 50Hz. Adjust the pulse width to control the servo's angle:
   • 1ms pulse width moves the servo to 0°.
   • 1.5ms pulse width moves the servo to 90° (neutral position).
   • 2ms pulse width moves the servo to 180°.

• Power Supply: Ensure the power supply can provide sufficient current for the servo, especially under load.
• Avoid Overloading: Do not exceed the torque rating of the servo to prevent damage.
• Signal Stability: Use a stable PWM signal to avoid jittery or erratic movements.
• External Power: For multiple servos, use an external power source to avoid overloading the microcontroller's power supply.

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 to control the servo

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

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

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

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

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

1. Servo Not Moving:

   • Cause: Insufficient power supply.
   • Solution: Use a power source capable of providing enough current.

2. Jittery Movements:

   • Cause: Unstable PWM signal or electrical noise.
   • Solution: Ensure a clean PWM signal and use decoupling capacitors if necessary.

3. Overheating:

   • Cause: Overloading the servo or continuous operation under high torque.
   • Solution: Reduce the load or allow the servo to cool down periodically.

4. Servo Moves Erratically:

   • Cause: Incorrect wiring or signal interference.
   • Solution: Double-check connections and ensure proper grounding.

• Q: Can I power the servo directly from the Arduino?
  A: While possible for small servos, it is recommended to use an external power source to avoid overloading the Arduino.

• Q: How do I control multiple servos?
  A: Use multiple PWM pins on the microcontroller or a dedicated servo driver board.

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

• Q: What happens if I exceed the torque rating?
  A: Exceeding the torque rating can damage the servo's gears or motor. Always operate within the specified limits.