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GPIO Project 7 - Stepper motor intro

Beginner

30 Minuten

114,90

In this project, you will learn how to control a stepper motor using a Raspberry Pi. A stepper motor rotates in precise steps, allowing you to accurately control movement. This project uses a 28BYJ-48 stepper motor and a ULN2003 driver.

Connection diagram

Connect the stepper motor to the ULN2003 driver:
- Connect the connector of the stepper motor to the header of the ULN2003 driver.
Connect the ULN2003 driver to the Raspberry Pi:
- IN1: Connect to GPIO 17 (pin 11).
- IN2: Connect to GPIO 27 (pin 13).
- IN3: Connect to GPIO 22 (pin 15).
- IN4: Connect to GPIO 23 (pin 16).
Power supply for the ULN2003 driver:
- VCC: Connect to 5V (pin 2).
- GND: Connect toGND (pin 6).

Pinout Reference

GPIO	Pin #	Function	Connection
GPIO 17	Pin 11	IN1	ULN2003 driver
GPIO 27	Pin 13	IN2	ULN2003 driver
GPIO 22	Pin 15	IN3	ULN2003 driver
GPIO 23	Pin 16	IN4	ULN2003 driver
5V	Pin 2	Nutrition	ULN2003 driver
GND	Pin 6	Earth (Ground)	ULN2003 driver

Python-code in Thonny

Step 1: Install RPi.GPIO

Make sure the RPi.GPIO library is installed. This is usually included in Raspberry Pi OS by default.

pip install RPi.GPIO

Step 2: Write your code

Open the Thonny Python IDE and enter the following code:

import RPi.GPIO as GPIO
from time import sleep

# GPIO-pinnen koppelen aan ULN2003 IN-pinnen
IN1 = 17
IN2 = 27
IN3 = 22
IN4 = 23

# Pinnen instellen
GPIO.setmode(GPIO.BCM)
GPIO.setup(IN1, GPIO.OUT)
GPIO.setup(IN2, GPIO.OUT)
GPIO.setup(IN3, GPIO.OUT)
GPIO.setup(IN4, GPIO.OUT)

# Stepper motor sequence (4-fase stappen)
step_sequence = [
    [1, 0, 0, 0],
    [1, 1, 0, 0],
    [0, 1, 0, 0],
    [0, 1, 1, 0],
    [0, 0, 1, 0],
    [0, 0, 1, 1],
    [0, 0, 0, 1],
    [1, 0, 0, 1]
]

def set_step(w1, w2, w3, w4):
    """Stel de status van de motorpinnen in."""
    GPIO.output(IN1, w1)
    GPIO.output(IN2, w2)
    GPIO.output(IN3, w3)
    GPIO.output(IN4, w4)

def step_motor(steps, delay, reverse=False):
    """Draai de motor een aantal stappen."""
    if reverse:
        sequence = step_sequence[::-1]  # Keer de sequentie om
    else:
        sequence = step_sequence
    
    for _ in range(abs(steps)):
        for step in sequence:
            # Zorg ervoor dat elke stap 4 waarden bevat
            if len(step) == 4:
                set_step(*step)
            else:
                raise ValueError("Step sequence must contain exactly 4 values")
            sleep(delay)

try:
    print("Stepper motor draait vooruit...")
    step_motor(512, 0.002)  # Draai 512 stappen vooruit
    sleep(1)

    print("Stepper motor draait achteruit...")
    step_motor(512, 0.002, reverse=True)  # Draai 512 stappen achteruit
    sleep(1)

except KeyboardInterrupt:
    print("\nProgramma gestopt.")
finally:
    GPIO.cleanup()  # Reset de GPIO-instellingen

Step 3: Save the file

Click File > Save As and name the file stepper_motor_intro.py.

Step 4: Run the script

Click the greenRun button (▶) at the top the Thonny interface.

How does it work?

Step sequence:
- The engine runs through the sequences in the step_sequence list to activate.
- The step_motor()-function checks how many steps the motor turns and the speed of the steps.
Adjust speed:
- Adjust the value of delayon in the step_motor()function to change the speed of the motor.
Adjust direction:
- Use a negative value for steps to turn the engine in the other direction.

Result

Forward rotation: The stepper motor rotates forward 512 steps (one full rotation).
Backward rotation: The stepper motor rotates backward 512 steps.

Experimenting

Adjust speed:
- Change the value of delay in step_motor() (for example 0.001 for faster or 0.005 for slower rotation).
Adjust number of steps:
- Adjust the number of steps to perform half a rotation (256 steps) or multiple rotations.
Combined movements:
- Combine forward and backward movements at different speeds to create complex movements.