Stepper motors on the pi

Out playing with stepper motors today, using 28bjy-48 and a uln2003 board which I purchased off eBay a while back for about a pound each but had to wait for a month for them to arrive, obviously buying them from a uk company would have meant next day delivery but for about double and sometimes triple the price.

To make a stepper motor work it needs to be provided with a sequence of high and low signals to each of the four inputs in a correct sequence of high and low signals the motor will turn rotating the spindle, this motor can turn clockwise and also anti clockwise by reversing the sequence.

I cannot remember the coding I originally used, but Matt Hawkins over at raspberry-pi-spy has written an excellent short python script which is excellent to play with to get a good understanding of how a, the script works and b, the stepper motor works.

Thanks Matt for the following script:

# Name: Stepper Motor # # Author: matt.hawkins # # Created: 11/07/2012 # Copyright: (c) matt.hawkins 2012 #----------------------------------- #!/usr/bin/env python   # Import required libraries import time import RPi.GPIO as GPIO   # Use BCM GPIO references # instead of physical pin numbers GPIO.setmode(GPIO.BCM)   # Define GPIO signals to use # Pins 18,22,24,26 # GPIO24,GPIO25,GPIO8,GPIO7 StepPins = [24,25,8,7]   # Set all pins as output for pin in StepPins:   print "Setup pins"   GPIO.setup(pin,GPIO.OUT)   GPIO.output(pin, False)   # Define some settings StepCounter = 0 WaitTime = 0.5   # Define simple sequence StepCount1 = 4 Seq1 = [] Seq1 = range(0, StepCount1) Seq1[0] = [1,0,0,0] Seq1[1] = [0,1,0,0] Seq1[2] = [0,0,1,0] Seq1[3] = [0,0,0,1]   # Define advanced sequence # as shown in manufacturers datasheet StepCount2 = 8 Seq2 = [] Seq2 = range(0, StepCount2) Seq2[0] = [1,0,0,0] Seq2[1] = [1,1,0,0] Seq2[2] = [0,1,0,0] Seq2[3] = [0,1,1,0] Seq2[4] = [0,0,1,0] Seq2[5] = [0,0,1,1] Seq2[6] = [0,0,0,1] Seq2[7] = [1,0,0,1]   # Choose a sequence to use Seq = Seq1 StepCount = StepCount1   # Start main loop while 1==1:     for pin in range(0, 4):     xpin = StepPins[pin]     if Seq[StepCounter][pin]!=0:       print " Step %i Enable %i" %(StepCounter,xpin)       GPIO.output(xpin, True)     else:       GPIO.output(xpin, False)     StepCounter += 1     # If we reach the end of the sequence   # start again   if (StepCounter==StepCount):     StepCounter = 0   if (StepCounter<0):     StepCounter = StepCount     # Wait before moving on   time.sleep(WaitTime) 5v and gnd connections should be obvious while the other four go to pins 18, 22, 24, 26. (Ch1, ch2, ch3, ch4)