Introduction

The A4988 stepper motor driver is a complete microstepping motor driver with built-in translator for easy operation. It’s designed to operate bipolar stepper motors in full-, half-, quarter-, eighth-, and sixteenth-step modes, with an output drive capacity of up to 35V and ±2A.

Key Features

Technical Specifications

Pin Configuration

Pin	Description	Connection
VMOT	Motor power (8-35V)	Connect to power supply
GND	Ground	Connect to power supply ground
VDD	Logic voltage (3-5.5V)	Connect to Arduino 5V
STEP	Step input	Connect to Arduino digital pin
DIR	Direction input	Connect to Arduino digital pin
ENABLE	Enable (active LOW)	Optional control
MS1, MS2, MS3	Microstep selection	Connect to GND or VDD
1A, 1B, 2A, 2B	Motor coil connections	Connect to stepper motor

Current Adjustment

1. Power off the driver and disconnect motor
2. Set multimeter to measure DC voltage (200mV range)
3. Place probes on the potentiometer and GND
4. Power on the system
5. Adjust potentiometer until VREF = I_Trip × 0.8
6. Example: For 1A current, set VREF to 0.8V

Microstep Configuration

Arduino Connection Example

// Basic A4988 Stepper Control
const int dirPin = 2;
const int stepPin = 3;
const int stepsPerRevolution = 200;

void setup() {
  pinMode(dirPin, OUTPUT);
  pinMode(stepPin, OUTPUT);
}

void loop() {
  // Set direction clockwise
  digitalWrite(dirPin, HIGH);
  
  // Spin motor slowly
  for(int x = 0; x < stepsPerRevolution; x++) {
    digitalWrite(stepPin, HIGH);
    delayMicroseconds(1000);
    digitalWrite(stepPin, LOW);
    delayMicroseconds(1000);
  }
  
  delay(1000); // Wait a second
  
  // Set direction counterclockwise
  digitalWrite(dirPin, LOW);
  
  // Spin motor quickly
  for(int x = 0; x < stepsPerRevolution; x++) {
    digitalWrite(stepPin, HIGH);
    delayMicroseconds(500);
    digitalWrite(stepPin, LOW);
    delayMicroseconds(500);
  }
  
  delay(1000); // Wait a second
}

Heatsink Installation

1. Clean the metal surface of the A4988 chip
2. Apply thermal adhesive or thermal tape
3. Press heatsink firmly onto the chip
4. Allow adhesive to cure if needed
5. Ensure no electrical contact with other components

Troubleshooting

Application Examples