Project Overview

This comprehensive guide demonstrates how to control a stepper motor using a Raspberry Pi Pico microcontroller and an A4988 stepper motor driver in the Wokwi online simulator. Learn precise motor control, microstepping, direction changes, and speed adjustment for robotics, CNC, and automation projects.

What You'll Learn

Stepper motor operation principles
A4988 driver module configuration
Raspberry Pi Pico GPIO control
Motor speed and direction programming
Microstepping techniques
Wokwi simulation for motor projects

Components Required in Wokwi

Diagram .json:

{
  "version": 1,
  "author": "Uri Shaked",
  "editor": "wokwi",
  "parts": [
    { "type": "wokwi-pi-pico", "id": "pico", "top": 63.95, "left": 86.4, "attrs": {} },
    { "type": "wokwi-a4988", "id": "drv1", "top": 91.4, "left": 226, "rotate": 270, "attrs": {} },
    {
      "type": "wokwi-stepper-motor",
      "id": "stepper1",
      "top": -179.4,
      "left": 141.6,
      "attrs": { "display": "angle" }
    }
  ],
  "connections": [
    [ "drv1:1B", "stepper1:B-", "black", [ "v0" ] ],
    [ "drv1:1A", "stepper1:B+", "green", [ "v0" ] ],
    [ "stepper1:A+", "drv1:2A", "blue", [ "v0" ] ],
    [ "stepper1:A-", "drv1:2B", "red", [ "v0" ] ],
    [ "drv1:SLEEP", "drv1:RESET", "green", [ "v15.92", "h-9.9" ] ],
    [ "drv1:STEP", "pico:GP3", "orange", [ "v130.8", "h-203.87", "v-163.2" ] ],
    [ "drv1:DIR", "pico:GP2", "violet", [ "v140.4", "h-223.07", "v-182.4" ] ],
    [ "drv1:GND.2", "pico:GND.8", "black", [ "v0" ] ],
    [ "pico:VBUS", "drv1:VDD", "red", [ "h0" ] ]
  ]
}

Hardware (Virtual):

1x Raspberry Pi Pico board
1x A4988 Stepper Motor Driver module
1x NEMA 17 Stepper Motor (or similar bipolar stepper)
Power supply (12V for motor - simulated in Wokwi)
Jumper wires (automatic in Wokwi)

Software:

MicroPython firmware
Motor control library

Understanding Stepper Motors

What is a Stepper Motor?

A stepper motor is a brushless DC motor that divides a full rotation into equal steps. Unlike regular DC motors, steppers move in precise, repeatable increments.

Key Characteristics:

Step Angle: Typically 1.8° (200 steps per revolution)
Bipolar vs Unipolar: This project uses bipolar (4 wires)
Holding Torque: Motor stays in position when powered
Precise Positioning: No feedback sensors needed

Common Applications:

3D printers
CNC machines
Robotics
Camera sliders
Automated curtains

Understanding the A4988 Driver

The A4988 is a popular stepper motor driver that:

Controls motor current
Enables microstepping (1/16 step resolution)
Protects against overcurrent
Simplifies control to just STEP and DIR signals

A4988 Pin Configuration:

Pin Name	Function	Description
VMOT	Motor Power	8-35V power supply for motor
GND	Ground	Power ground
1A, 1B	Motor Coil 1	Connect to motor coil A
2A, 2B	Motor Coil 2	Connect to motor coil B
VDD	Logic Power	3-5.5V logic power (from Pico)
GND	Logic Ground	Logic ground
STEP	Step Input	Pulse to move one step
DIR	Direction	HIGH = CW, LOW = CCW
ENABLE	Enable	LOW = enabled, HIGH = disabled
MS1, MS2, MS3	Microstep Select	Set stepping resolution
RESET	Reset	Keep HIGH for normal operation
SLEEP	Sleep Mode	Keep HIGH for operation

Step-by-Step Wokwi Setup Instructions

Step 1: Create New Raspberry Pi Pico Project

Navigate to https://wokwi.com
Click "New Project"
Select "Raspberry Pi Pico"
Pico board appears on canvas

Step 2: Add A4988 Stepper Driver Module

Click the blue "+" (Add Part) button
Search for "A4988" or "Stepper Driver"
Select "A4988 Stepper Motor Driver"
Place it to the right of the Pico

Note: If A4988 isn't available, search for generic stepper driver modules.

Step 3: Add Stepper Motor

Click the "+" button
Search for "Stepper Motor" or "NEMA 17"
Select "Stepper Motor"
Place it above the A4988 driver

Step 4: Understanding the Wiring Connections

Complete Connection Table:

A4988 Pin	Raspberry Pi Pico Pin	Wire Color	Notes
VDD	3V3 (OUT)	Red	Logic power 3.3V
GND	GND	Black	Logic ground
STEP	GPIO 2	Blue	Step pulse signal
DIR	GPIO 3	Green	Direction control
ENABLE	GND	Black	Always enabled (grounded)
RESET	VDD	Red	Keep high (connect to VDD)
SLEEP	VDD	Red	Keep awake (connect to VDD)
VMOT	External 12V+	Red	Motor power supply
GND	External GND	Black	Motor power ground

Motor to A4988 Connections:

Motor Wire	A4988 Pin	Coil
Coil A+ (Red)	1A	Coil 1
Coil A- (Green)	1B	Coil 1
Coil B+ (Blue)	2A	Coil 2
Coil B- (Yellow)	2B	Coil 2

Microstepping Configuration (Optional):

MS1	MS2	MS3	Step 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

For this tutorial, leave MS1, MS2, MS3 unconnected (defaults to full step).

Step 5: Wire the Circuit in Wokwi

Power Connections:

Logic Power (Pico to A4988):
- Pico 3V3 (OUT) → A4988 VDD (red wire)
- Pico GND → A4988 GND (black wire)

Motor Power (External Supply to A4988):
- In Wokwi, click "+" and add "Power Supply"
- Power Supply +12V → A4988 VMOT (red wire)
- Power Supply GND → A4988 GND (black wire)
- Also connect Power Supply GND to Pico GND (common ground)

Control Signal Connections:

Pico GPIO 2 → A4988 STEP (blue wire)
Pico GPIO 3 → A4988 DIR (green wire)
A4988 ENABLE → Pico GND (enables driver)
A4988 RESET → A4988 VDD (keeps driver active)
A4988 SLEEP → A4988 VDD (prevents sleep mode)

Motor Connections:

Stepper Motor Coil A+ (Red) → A4988 1A
Stepper Motor Coil A- (Green) → A4988 1B
Stepper Motor Coil B+ (Blue) → A4988 2A
Stepper Motor Coil B- (Yellow) → A4988 2B

Wokwi Tip: Colors are suggested - Wokwi automatically assigns colors. Click each pin and drag to create connections.

CODE:

// Raspberry Pi Pico + Stepper Motor Example

#define DIR_PIN 2
#define STEP_PIN 3

void setup() {
  pinMode(STEP_PIN, OUTPUT);
  pinMode(DIR_PIN, OUTPUT);
  digitalWrite(STEP_PIN, LOW);
}

void loop() {
  // Move 200 steps (one rotation) CW over one second
  digitalWrite(DIR_PIN, HIGH);
  for (int i = 0; i < 200; i++) {
    digitalWrite(STEP_PIN, HIGH);
    digitalWrite(STEP_PIN, LOW);
    delay(5); // 5 ms * 200 = 1 second
  }

  delay(500); // Wait half a second

  // Move 200 steps (one rotation) CCW over 400 millis
  digitalWrite(DIR_PIN, LOW); 
  for (int i = 0; i < 200; i++) {
    digitalWrite(STEP_PIN, HIGH);
    digitalWrite(STEP_PIN, LOW);
    delay(2); // 2 ms * 200 = 0.4 seconds
  }

  delay(1000); // Wait another second
}

ROBOTICS

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How to Control Stepper Motor with Raspberry Pi Pico and A4988 Driver in Wokwi - Complete Step-by-Step Tutorial