PRE2017 3 11 Python Code

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  1. !/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

  1. 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()

  1. Runs end_run if ctrl+C is clicked

signal.signal(signal.SIGINT, end_run)

  1. 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"

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