步進電機的優點在於它能夠被精確定位，正向或反向一次性轉動“一步”，並且也能夠連續轉動。本次實驗，我們選用的舵機驅動晶片是ULN2003A，ULN2003 是高耐壓、大電流複合電晶體陣列，由七個矽NPN 複合電晶體組成。為了方便起見，我們用了ULN2003A模組，電路連線方式如下圖：

#!/usr/bin/env python
#########################################################
#	File name: stepMotor.py
#	   Author: Jason Dai
#	     Date: 2015/01/26
#########################################################
import RPi.GPIO as GPIO
import time

IN1 = 11    # pin11
IN2 = 12
IN3 = 13
IN4 = 15

def setStep(w1, w2, w3, w4):
	GPIO.output(IN1, w1)
	GPIO.output(IN2, w2)
	GPIO.output(IN3, w3)
	GPIO.output(IN4, w4)

def stop():
	setStep(0, 0, 0, 0)

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

def backward(delay, steps):  
	for i in range(0, steps):
		setStep(0, 0, 0, 1)
		time.sleep(delay)
		setStep(0, 0, 1, 0)
		time.sleep(delay)
		setStep(0, 1, 0, 0)
		time.sleep(delay)
		setStep(1, 0, 0, 0)
		time.sleep(delay)

def setup():
	GPIO.setwarnings(False)
	GPIO.setmode(GPIO.BOARD)       # Numbers GPIOs by physical location
	GPIO.setup(IN1, GPIO.OUT)      # Set pin's mode is output
	GPIO.setup(IN2, GPIO.OUT)
	GPIO.setup(IN3, GPIO.OUT)
	GPIO.setup(IN4, GPIO.OUT)

def loop():
	while True:
		print "backward..."
		backward(0.003, 512)  # 512 steps --- 360 angle
		
		print "stop..."
		stop()                 # stop
		time.sleep(3)          # sleep 3s
		
		print "forward..."
		forward(0.005, 512)
		
		print "stop..."
		stop()
		time.sleep(3)

def destroy():
	GPIO.cleanup()             # Release resource

if __name__ == '__main__':     # Program start from here
	setup()
	try:
		loop()
	except KeyboardInterrupt:  # When 'Ctrl+C' is pressed, the child function destroy() will be  executed.
		destroy()

 

執行程式：

python stepMotor.py