Controlling a DC Motor

This scenario demonstrates how to control a DC motor's rotation direction and speed using Arduino with the Pololu TB6612FNG Dual Motor Driver.

• Familiarize yourself with Arduino hardware reference.
• Understand basic PWM concepts.
• Familiarity with the Pololu TB6612FNG motor driver.

Motor specifications:

• Voltage: 12 V DC
• Speed: 5 rpm
• Torque: 20 N·cm
• Shaft Diameter: 4 mm

• Arduino programming fundamentals
• Arduino Uno Hardware Reference

Implement a program that rotates the DC motor forward at full speed for 5 seconds, pauses for 2 seconds, reverses at half speed for 5 seconds, then pauses again for 2 seconds, repeatedly.

const int AIN1 = 12;
const int AIN2 = 11;
const int PWMA = 3;

Configure pin modes:

void setup() {
  pinMode(AIN1, OUTPUT);
  pinMode(AIN2, OUTPUT);
  pinMode(PWMA, OUTPUT);
}

Implement motor control logic:

void loop() {
  // Rotate Forward at full speed
  digitalWrite(AIN1, HIGH);
  digitalWrite(AIN2, LOW);
  analogWrite(PWMA, 255);  // Full speed
  delay(5000);             // 5 seconds
 
  // Stop motor
  digitalWrite(AIN1, LOW);
  digitalWrite(AIN2, LOW);
  delay(2000);             // 2 seconds pause
 
  // Rotate Reverse at half speed
  digitalWrite(AIN1, LOW);
  digitalWrite(AIN2, HIGH);
  analogWrite(PWMA, 128);  // Half speed
  delay(5000);             // 5 seconds
 
  // Stop motor again
  digitalWrite(AIN1, LOW);
  digitalWrite(AIN2, LOW);
  delay(2000);             // 2 seconds pause
}

Observe the motor rotating in both directions with clear speed differences. Verify pauses between rotations.

If the motor doesn’t rotate or behaves erratically:

• Check power supply (motor needs 12V DC).
• Confirm motor driver connections.
• Verify Arduino pin assignments match the code.