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A4988 Stepper Motor Driver Module

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Ekostra Electronics

April 13, 2025

On April 13, 2025

A4988 Stepper Motor Driver Module

Microstepping bipolar stepper motor driver with up to 2A per coil and 1/16 step resolution

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

🔌 Microstepping

1/16 step resolution

⚡ High Current

Up to 2A per coil (with heatsink)

🔒 Protection

Thermal shutdown & overcurrent

🔄 Simple Control

STEP/DIR interface

🔧 Adjustable Current

Via potentiometer

💡 Status LEDs

Power and fault indicators

Technical Specifications

Operating Voltage	8-35V
Logic Voltage	3-5.5V
Max Current per Coil	2A (with heatsink)
Microstep Resolution	Full, 1/2, 1/4, 1/8, 1/16
Step Frequency	Up to 250kHz
Protection Features	Thermal shutdown, undervoltage lockout, crossover-current
Package	QFN-28 (5mm × 5mm)
Module Dimensions	20mm × 15mm × 10mm

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

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

Formula: VREF = Current Limit × 0.8 (e.g., 1A × 0.8 = 0.8V)

Microstep Configuration

MS1	MS2	MS3	Microstep Resolution
LOW	LOW	LOW	Full step
HIGH	LOW	LOW	1/2 step
LOW	HIGH	LOW	1/4 step
HIGH	HIGH	LOW	1/8 step
HIGH	HIGH	HIGH	1/16 step

Arduino Connection Example

A4988 Arduino Wiring

// 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
}

// 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

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

Important: Always use a heatsink when driving currents above 1A

Troubleshooting

Motor Not Moving

Check power supply connections
Verify ENABLE pin is LOW (or disconnected)
Confirm STEP pulses are being sent
Check current adjustment

Driver Gets Hot

Ensure proper heatsink installation
Reduce current if not needed
Check for short circuits
Improve ventilation

Inconsistent Movement

Verify microstep settings
Check motor wiring connections
Ensure sufficient power supply
Slow down STEP pulse frequency

Application Examples

🖨️ 3D Printers

Precise axis control

🤖 CNC Machines

Accurate tool positioning

📷 Camera Sliders

Smooth motion control

🔬 Lab Automation

Precise liquid handling

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A4988 Stepper Motor Driver Module

A4988 Stepper Motor Driver Module

Introduction