步进电机的优点在于它能够被精确定位，正向或反向一次性转动“一步”，并且也能够连续转动。本次实验，我们选用的舵机驱动芯片是ULN2003A，ULN2003 是高耐压、大电流复合晶体管阵列，由七个硅NPN 复合晶体管组成。为了方便起见，我们用了ULN2003A模块，电路连接方式如下图：

#!/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()

运行程序：

python stepMotor.py