How to Use A4988 Stepper Motor Driver (Red): Examples, Pinouts, and Specs

The A4988 Stepper Motor Driver (Red) is a compact and versatile driver module designed for controlling bipolar stepper motors. It features adjustable current control, microstepping capabilities (up to 1/16 steps), and built-in thermal shutdown protection, making it an excellent choice for applications requiring precise motor control. This driver is widely used in 3D printers, CNC machines, robotics, and other motion control systems.

• 3D printers for precise movement of axes
• CNC machines for accurate tool positioning
• Robotics for controlling robotic arms or wheels
• Automated systems requiring stepper motor control

Below are the key technical details and pin configuration for the A4988 Stepper Motor Driver:

1. Power Connections:

   • Connect VMOT to the motor power supply (8V to 35V).
   • Connect GND to the ground of the power supply.
   • Connect VDD to the logic voltage supply (3.3V or 5V).

2. Motor Connections:

   • Connect the stepper motor's two coils to A1, A2 and B1, B2. Ensure the correct pairing of the motor wires.

3. Control Pins:

   • Use the STEP pin to control the motor's steps. Each rising edge moves the motor one step.
   • Use the DIR pin to set the motor's rotation direction (high or low).
   • Configure microstepping by setting MS1, MS2, and MS3 according to the desired resolution:
     • Full step: MS1 = 0, MS2 = 0, MS3 = 0
     • 1/2 step: MS1 = 1, MS2 = 0, MS3 = 0
     • 1/4 step: MS1 = 0, MS2 = 1, MS3 = 0
     • 1/8 step: MS1 = 1, MS2 = 1, MS3 = 0
     • 1/16 step: MS1 = 1, MS2 = 1, MS3 = 1

4. Current Limiting:

   • Adjust the current limit using the potentiometer on the module. This prevents overheating and protects the motor.

5. Enable/Disable:

   • Use the ENABLE pin to enable or disable the driver. Pull it low to enable and high to disable.

Below is an example of how to control a stepper motor using the A4988 and an Arduino UNO:

// Define control pins
#define STEP_PIN 3  // Connect to STEP pin on A4988
#define DIR_PIN 4   // Connect to DIR pin on A4988

void setup() {
  pinMode(STEP_PIN, OUTPUT); // Set STEP pin as output
  pinMode(DIR_PIN, OUTPUT);  // Set DIR pin as output

  digitalWrite(DIR_PIN, HIGH); // Set initial direction (HIGH = clockwise)
}

void loop() {
  // Generate steps to move the motor
  for (int i = 0; i < 200; i++) { // 200 steps for one revolution (1.8°/step)
    digitalWrite(STEP_PIN, HIGH); // Step pulse high
    delayMicroseconds(1000);      // Wait 1ms (adjust for speed)
    digitalWrite(STEP_PIN, LOW);  // Step pulse low
    delayMicroseconds(1000);      // Wait 1ms
  }

  delay(1000); // Wait 1 second before changing direction

  // Change direction
  digitalWrite(DIR_PIN, LOW); // Set direction to counterclockwise
  delay(1000); // Wait 1 second before next loop
}

• Heat Management: The A4988 can get hot during operation. Use a heatsink or active cooling if necessary.
• Current Limiting: Always set the current limit to match your stepper motor's rated current to avoid damage.
• Power Supply: Ensure the motor power supply voltage is within the specified range (8V to 35V).
• Decoupling Capacitors: Add a 100µF capacitor across VMOT and GND to reduce voltage spikes.

1. Motor Not Moving:

   • Check all connections, especially the motor coils (A1, A2, B1, B2).
   • Verify that the STEP pin is receiving pulses.
   • Ensure the ENABLE pin is pulled low.

2. Motor Vibrates but Doesn't Rotate:

   • Verify the correct pairing of motor wires for the coils.
   • Check the microstepping configuration (MS1, MS2, MS3).

3. Driver Overheating:

   • Ensure the current limit is set correctly using the potentiometer.
   • Add a heatsink or active cooling to the driver.

4. Motor Moves Erratically:

   • Check for noise or interference on the control signals.
   • Ensure the power supply voltage is stable and within range.

Q: Can I use the A4988 with a unipolar stepper motor?
A: No, the A4988 is designed for bipolar stepper motors only.

Q: How do I calculate the current limit?
A: Use the formula: Current Limit = VREF / (8 × RS), where RS is the sense resistor value (typically 0.1Ω).

Q: Can I daisy-chain multiple A4988 drivers?
A: Yes, but ensure each driver has its own control signals and power supply connections.

Q: What happens if I exceed the maximum current?
A: The driver will activate overcurrent protection, but prolonged overcurrent can damage the module. Always set the current limit properly.