Adafruit's Raspberry Pi Lesson 10. Stepper Motors

by Simon Monk

published January 23, 2013, last edited January 21, 2025

posted in Raspberry Pi/ Learn Raspberry Pi Robotics & CNC Raspberry Pi/ Pi A+, B+, 2, 3

Beginner

Skill guide

Software

The Setup

We are using the CircuitPython Libraries that are part of adafruit-blinka. See CircuitPython Libraries on Raspberry Pi to get a fresh Raspberry Pi setup.

If you have a running Raspberry Pi with an up to date copy of Raspbian you can simply run the following command to install adafruit-blinka.

The software is exactly the same on all 40-pin and 20-pin Raspberry Pi models. You can use the L293D or ULN2803 chips without any modification the following code:

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$ sudo pip3 install adafruit-blinka

$ sudo pip3 install adafruit-blinka

The Code

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# SPDX-FileCopyrightText: 2019 Mikey Sklar for Adafruit Industries
#
# SPDX-License-Identifier: MIT

import time
import board
import digitalio

enable_pin = digitalio.DigitalInOut(board.D18)
coil_A_1_pin = digitalio.DigitalInOut(board.D4)
coil_A_2_pin = digitalio.DigitalInOut(board.D17)
coil_B_1_pin = digitalio.DigitalInOut(board.D23)
coil_B_2_pin = digitalio.DigitalInOut(board.D24)

enable_pin.direction = digitalio.Direction.OUTPUT
coil_A_1_pin.direction = digitalio.Direction.OUTPUT
coil_A_2_pin.direction = digitalio.Direction.OUTPUT
coil_B_1_pin.direction = digitalio.Direction.OUTPUT
coil_B_2_pin.direction = digitalio.Direction.OUTPUT

enable_pin.value = True

def forward(delay, steps):
    i = 0
    while i in range(0, steps):
        setStep(1, 0, 1, 0)
        time.sleep(delay)
        setStep(0, 1, 1, 0)
        time.sleep(delay)
        setStep(0, 1, 0, 1)
        time.sleep(delay)
        setStep(1, 0, 0, 1)
        time.sleep(delay)
        i += 1

def backwards(delay, steps):
    i = 0
    while i in range(0, steps):
        setStep(1, 0, 0, 1)
        time.sleep(delay)
        setStep(0, 1, 0, 1)
        time.sleep(delay)
        setStep(0, 1, 1, 0)
        time.sleep(delay)
        setStep(1, 0, 1, 0)
        time.sleep(delay)
        i += 1

def setStep(w1, w2, w3, w4):
    coil_A_1_pin.value = w1
    coil_A_2_pin.value = w2
    coil_B_1_pin.value = w3
    coil_B_2_pin.value = w4

while True:
    user_delay = input("Delay between steps (milliseconds)?")
    user_steps = input("How many steps forward? ")
    forward(int(user_delay) / 1000.0, int(user_steps))
    user_steps = input("How many steps backwards? ")
    backwards(int(user_delay) / 1000.0, int(user_steps))

# SPDX-FileCopyrightText: 2019 Mikey Sklar for Adafruit Industries
#
# SPDX-License-Identifier: MIT

import time
import board
import digitalio

enable_pin = digitalio.DigitalInOut(board.D18)
coil_A_1_pin = digitalio.DigitalInOut(board.D4)
coil_A_2_pin = digitalio.DigitalInOut(board.D17)
coil_B_1_pin = digitalio.DigitalInOut(board.D23)
coil_B_2_pin = digitalio.DigitalInOut(board.D24)

enable_pin.direction = digitalio.Direction.OUTPUT
coil_A_1_pin.direction = digitalio.Direction.OUTPUT
coil_A_2_pin.direction = digitalio.Direction.OUTPUT
coil_B_1_pin.direction = digitalio.Direction.OUTPUT
coil_B_2_pin.direction = digitalio.Direction.OUTPUT

enable_pin.value = True

def forward(delay, steps):
    i = 0
    while i in range(0, steps):
        setStep(1, 0, 1, 0)
        time.sleep(delay)
        setStep(0, 1, 1, 0)
        time.sleep(delay)
        setStep(0, 1, 0, 1)
        time.sleep(delay)
        setStep(1, 0, 0, 1)
        time.sleep(delay)
        i += 1

def backwards(delay, steps):
    i = 0
    while i in range(0, steps):
        setStep(1, 0, 0, 1)
        time.sleep(delay)
        setStep(0, 1, 0, 1)
        time.sleep(delay)
        setStep(0, 1, 1, 0)
        time.sleep(delay)
        setStep(1, 0, 1, 0)
        time.sleep(delay)
        i += 1

def setStep(w1, w2, w3, w4):
    coil_A_1_pin.value = w1
    coil_A_2_pin.value = w2
    coil_B_1_pin.value = w3
    coil_B_2_pin.value = w4

while True:
    user_delay = input("Delay between steps (milliseconds)?")
    user_steps = input("How many steps forward? ")
    forward(int(user_delay) / 1000.0, int(user_steps))
    user_steps = input("How many steps backwards? ")
    backwards(int(user_delay) / 1000.0, int(user_steps))

When the steppers are not moving, they are still 'activated' and hold their position. This draws power. If you don't need the steppers to 'hold' their position, you can call setStep(0,0,0,0) to release the coils. The motor will spin freely and wont draw a lot of current.

Page last edited January 21, 2025