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3.5 Controlling a Small Fan (DC Motor)

In this lesson, we’ll learn how to control a DC motor (like a small fan) using the Raspberry Pi Pico 2 W and an TA6586 motor driver. The TA6586 allows us to control the direction of the motor rotation—both clockwise and counterclockwise. Since DC motors require more current than the Pico can provide directly, we’ll use an external power supply to safely power the motor.

• DC Motor

• TA6586 - Motor Driver Chip

• Power Supply Module

Required Components

In this project, we need the following components.

It’s definitely convenient to buy a whole kit, here’s the link:

Name	ITEMS IN THIS KIT	PURCHASE LINK
Pico 2 W Starter Kit	450+	Pico 2 W Kit

You can also buy them separately from the links below.

SN	COMPONENT INTRODUCTION	QUANTITY	PURCHASE LINK
1	Getting to Know Pico 2 W	1
2	Micro USB Cable	1
3	Breadboard	1	BUY
4	Jumper Wires	Several	BUY
5	TA6586 - Motor Driver Chip	1
6	DC Motor	1	BUY
7	Li-po Charger Module	1
8	18650 Battery	1

Schematic

Wiring

Code

Note

• You can open the file 3.5_small_fan.ino under the path of pico-2w-kit-main/arduino/3.5_small_fan.

• Or copy this code into Arduino IDE.

• Don’t forget to select the board(Raspberry Pi Pico) and the correct port before clicking the Upload button.

// Define the pins connected to the motor driver
const int motor1A = 14; // Motor control pin 1
const int motor2A = 15; // Motor control pin 2

void setup() {
  // Initialize the motor control pins as OUTPUT
  pinMode(motor1A, OUTPUT);
  pinMode(motor2A, OUTPUT);
}

void loop() {
     // Rotate the motor clockwise
     clockwise();
     delay(1000); // Keep the motor running clockwise for 1 second

    // Stop the motor
    stopMotor();
    delay(1000); // Pause for 1 second

    // Rotate the motor counterclockwise
    anticlockwise();
    delay(1000); // Keep the motor running counterclockwise for 1 second

    // Stop the motor
    stopMotor();
    delay(1000); // Pause for 1 second
}

    // Function to rotate the motor clockwise
void clockwise()
{
    digitalWrite(motor1A, HIGH); // Set motor1A to HIGH
    digitalWrite(motor2A, LOW);  // Set motor2A to LOW
   // This combination causes the motor to rotate in the clockwise direction
}

// Function to rotate the motor counterclockwise
void anticlockwise()
{
    digitalWrite(motor1A, LOW);  // Set motor1A to LOW
    digitalWrite(motor2A, HIGH); // Set motor2A to HIGH
// This combination causes the motor to rotate in the counterclockwise direction
}

// Function to stop the motor
void stopMotor()
{
    digitalWrite(motor1A, LOW);  // Set motor1A to LOW
    digitalWrite(motor2A, LOW);  // Set motor2A to LOW
// Setting both pins LOW stops the motor
}

After uploading the code: the motor will rotate back and forth in a regular pattern.

Understanding the Code

1. Defining Control Pins:

   const int motor1A = 14; // Motor control pin 1
   const int motor2A = 15; // Motor control pin 2
   

2. Setting Pin Modes:

   void setup() {
     pinMode(motor1A, OUTPUT);
     pinMode(motor2A, OUTPUT);
   }
   

3. Controlling Motor Direction:

   • Clockwise Rotation: Sets motor1 HIGH and motor2A LOW, causing the motor to rotate in the clockwise direction.

   digitalWrite(motor1A, HIGH); // Set motor1A to HIGH
   digitalWrite(motor2A, LOW);  // Set motor2A to LOW
   

   • Counterclockwise Rotation: Sets motor1A LOW and motor2A HIGH, causing the motor to rotate in the counterclockwise direction.

   digitalWrite(motor1A, LOW);
   digitalWrite(motor2A, HIGH);
   

   • Keep the motor running clockwise for 1 second

   anticlockwise();
   delay(1000);
   

   • Keep the motor running counterclockwise for 1 second

   anticlockwise();
   delay(1000);
   

   1. Stopping the Motor:

   Sets both inputs LOW, stopping the motor.

   digitalWrite(motor1A, LOW);  // Set motor1A to LOW
   digitalWrite(motor2A, LOW);  // Set motor2A to LOW
   

   Pause for 1 second

   stopMotor();
   delay(1000);
   

Further Exploration

• Speed Control:

  Use Pulse Width Modulation (PWM) to control the speed of the motor by connecting the EN1 pin to a PWM-capable GPIO pin and varying the duty cycle.

• Sensor Integration:

  Incorporate sensors (e.g., limit switches, encoders) to create more advanced motor control systems.

Safety Precautions

• Power Supply:

  • Ensure that the external power supply voltage matches the motor’s voltage rating.

  • Do not power the motor directly from the Pico’s 3.3V pin.

• Current Draw:

  • Motors can draw significant current, especially during startup or when stalled.

  • Ensure that your power supply can handle the motor’s current requirements.

• Resetting the Pico:

  • In some cases, the motor’s current draw may cause voltage dips, leading the Pico to reset or disconnect.

  • If you encounter issues uploading code after running the motor, you can manually reset the Pico by connecting the RUN pin to GND momentarily.

  

Conclusion

In this lesson, you’ve learned how to control a DC motor using the Raspberry Pi Pico and the TA6586 motor driver. By controlling the inputs to the TA6586, you can change the direction of the motor’s rotation. This fundamental concept is essential in robotics, automation, and many other applications involving motors.