PRE2017 3 11 Python Code

From Control Systems Technology Group

#!/usr/bin/python
from pyzbar.pyzbar import decode    	# QR reader
import cv2                     		# Image reader
import urllib                  	 	# Url reader
import RPi.GPIO as GPIO    	 	# GPIO pin control
import time               	 	# Posibility to delay
import signal				# Cleanup when ending script

pin_servo1 = 29                        # Continuous servo 1
pin_servo2 = 33                        # Continuous servo 2

running = True

# Releases pins when script is interrupted
def end_run(signal,frame):
	global running
	print "Ctrl+C captured, ending script"
	running = False
	servo1.stop()
	servo2.stop()
	GPIO.cleanup()

# Runs end_run if ctrl+C is clicked
signal.signal(signal.SIGINT, end_run)

# Takes picture from camera, reads and evaluates QRcode
def QRscanner(passcode):
	grabbed, im = camera.read()       # Reads figure
	decodedObjects = decode(im)         # Decodes figure
	for obj in decodedObjects:          # Makes sure every code is read
	   	qrdata = obj.data           # Reads the alphanumerical code
    		# Cuts important information out of data and prints it
    		qrdata = qrdata.split("Open The Box ")[1]
    		qrdata = qrdata[:8]
    		if qrdata == passcode:        # Verifies if code is legit
			print "Correct code"
        		return True
		else:
			print "Wrong code"
	return False

GPIO.setmode(GPIO.BOARD)    		# Board numbering sceme

GPIO.setup(pin_servo1,GPIO.OUT)	# Sets pin as output
GPIO.setup(pin_servo2,GPIO.OUT)	# Sets pin as output

freq = 50                  		# Servo frequency [Hz]

servo1 = GPIO.PWM(pin_servo1, freq)	# Assigns frequency to pins
servo2 = GPIO.PWM(pin_servo2, freq)	# Assigns frequency to pins

s1left   = 5.0           # 100% velocity to left
s1center = 6.6           # no movement
s1right  = 8.0           # 100% velocity to right

s2left   = 5.0           # 100% velocity to left
s2center = 6.6           # no movement
s2right  = 8.0           # 100% velocity to right

cyldelay        = 2     # Time it takes for cylinder to rotate
dropdelay       = 5    # Time it takes to drop package
platformdelay   = 2     # Time it takes for platform to move down

servo1.start(s1center)	# Sets all servos still at centered position
servo2.start(s2center)	# Sets all servos still at centered position

passcode = "QL5WST4S"
camera = cv2.VideoCapture(0)
print "Program Running, provide QRcode"

while running:
	time.sleep(0.1)
	rightcode = QRscanner(passcode)
	if rightcode:
		print "Cylinders start opening"
	    	servo1.ChangeDutyCycle(s1left)	 # Cylinders open
    		time.sleep(cyldelay)             # Duration of cylinder movement
    		servo1.ChangeDutyCycle(s1center) # Cylinders stop moving
		print "Cylinders are open, package can be dropped"
    		time.sleep(dropdelay)            # Duration of package dropping
    		print "Cylinders start closing"
		servo1.ChangeDutyCycle(s1right)  # Cylinders close
   		time.sleep(cyldelay)             # Duration of cylinder movement
    		servo1.ChangeDutyCycle(s1center) # Cylinders stop moving
		print "Cylinders are closed, platform starts moving down"
		servo2.ChangeDutyCycle(s2left)   # Platform moves down
    		time.sleep(platformdelay)        # Duration of platform movement
    		servo2.ChangeDutyCycle(s2center) # Platform stops moving
		print "Platform stopped moving down, new code can be scanned"