A4988 Stepper Motor Driver

Name: A4988 Stepper Motor Driver
Brand: Allegro MicroSystems
Availability: InStock

Allegro MicroSystems

The A4988 is a microstepping bipolar stepper motor driver carrier. STEP/DIR pins advance the motor; MS1-MS3 select full to 1/16 microstepping; a trim pot sets the coil current limit. Widely used on 3D printers and CNC.

Manufacturer guide / datasheet

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In stock

Specifications

No specs listed.

Pinout

Pin	Name	Functions	Notes
1	ENABLE	GPIO	Active-low driver enable
2	MS1	GPIO	Microstep select 1
3	MS2	GPIO	Microstep select 2
4	MS3	GPIO	Microstep select 3
5	RESET	GPIO	Active-low reset (tie to SLEEP if unused)
6	SLEEP	GPIO	Active-low sleep
7	STEP	GPIO	One pulse = one (micro)step
8	DIR	GPIO	Rotation direction
9	VMOT	POWER	Motor supply 8-35V (add 100uF cap)
10	GND	GND	Motor ground
11	2B	—	Coil 2 output B
12	2A	—	Coil 2 output A
13	1A	—	Coil 1 output A
14	1B	—	Coil 1 output B
15	VDD	POWER	Logic supply 3-5.5V
16	GND	GND	Logic ground

Interactive pinout

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BOARD

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Starter code

Community starter examples — minimal, unofficial, and provided to get you wiring fast. Verify against the manufacturer datasheet before relying on them.

Arduino (C++)

Arduino library: AccelStepper

arduino

// A4988 stepper driver — community starter example
#include <AccelStepper.h>

#if defined(ESP32)
  #define STEP_PIN 4
  #define DIR_PIN  5
#else
  #define STEP_PIN 3
  #define DIR_PIN  4
#endif

// DRIVER mode = external STEP + DIR driver
AccelStepper stepper(AccelStepper::DRIVER, STEP_PIN, DIR_PIN);

void setup() {
  stepper.setMaxSpeed(1000);
  stepper.setAcceleration(500);
  stepper.moveTo(200);          // 200 full steps = 1 revolution
}

void loop() {
  if (stepper.distanceToGo() == 0) stepper.moveTo(-stepper.currentPosition());
  stepper.run();
}

MicroPython

python

# A4988 stepper driver (ESP32) — community starter example
# manual STEP/DIR pulsing (no external lib needed)
from machine import Pin
import time

step = Pin(4, Pin.OUT)   # STEP=GPIO4
dir_ = Pin(5, Pin.OUT)   # DIR=GPIO5
dir_.value(1)

for _ in range(200):     # 200 full steps = 1 rev
    step.value(1); time.sleep_us(800)
    step.value(0); time.sleep_us(800)

Wiring

Pin	Arduino Uno R3	ESP32 DevKitC (WROOM-32)	Notes
VDD	+5V	3V3	Logic supply 3-5.5 V
GND (logic)	GND	GND
STEP	D3	GPIO4
DIR	D4	GPIO5
ENABLE	-	-	Tie LOW to enable, or drive from a GPIO
VMOT/GND	-	-	Motor supply 8-35 V + 100 uF cap; 1A/1B/2A/2B go to the coils

Typical uses

Driving bipolar steppers (3D printers, CNC, robots)
Microstepping motion control