PRE2017 3 11 Python Code

1. !/usr/bin/python

from pyzbar.pyzbar import decode # QR reader from PIL import Image # Image reader import cv2 # Image reader import RPi.GPIO as GPIO # GPIO pin control import time # Posibility to delay import signal # Cleanup when ending script import sys # Needed to stop script if no camera

pin_s1 = 29 # Continuous servo 1 pin_s2 = 33 # Continuous servo 2 freq = 50 # Continuous servo frequency [Hz]

s1left = 5.00 # 100% velocity to left s1center = 6.70 # no movement s1right = 8.00 # 100% velocity to right

s2left = 5.00 # 100% velocity to left s2center = 6.60 # no movement s2right = 8.00 # 100% velocity to right

cyldelay = 2 # Time it takes for cylinder to rotate dropdelay = 5 # Time it takes to drop package pauzedelay = 2 # Time between cylinder rotation and platform movement platformdelay = 2 # Time it takes for platform to move down

imgname = "image2.jpg" # File frame is temporarily saved in camslot = 0 # Default camera slot

1. Imports allowed QRcodes

passcodelist = [] with open("authcodes") as file: passcodelist = [line.strip() for line in file]

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(passcodelist, camslot): camera = cv2.VideoCapture(camslot) # Initializes camera viewer grabbed, im = camera.read() # Reads figure

if not grabbed: # Searches for working camera if camslot < 5: camstr = "No camera connected in slot: " + str(camslot) print(camstr) camslot = camslot + 1 return False, camslot else: print("No camera connected") servo1.stop() servo2.stop() GPIO.cleanup() sys.exit()

cv2.imwrite(imgname,im) # Converts image to jpg img = Image.open(imgname) # Reads jpg decodedObjects = decode(img) # Decodes image for obj in decodedObjects: # Makes sure every code is read qrdata = obj.data # Reads the alphanumerical code for passcode in passcodelist:

   			if passcode in qrdata:      # Verifies if code is legit

print("Correct code, cylinders start opening")

       			return True, camslot

else: print("Wrong code") return False, camslot

GPIO.setmode(GPIO.BOARD) # Board numbering sceme pins GPIO.setup(pin_s1, GPIO.OUT) # Sets pins as output GPIO.setup(pin_s2, GPIO.OUT) servo1 = GPIO.PWM(pin_s1, freq) # Assigns frequency to pins servo2 = GPIO.PWM(pin_s2, freq) servo1.start(s1center) # Starts servos in neutral position servo2.start(s2center)

running = True print("Program Running, provide QR-code")

while running: rightcode, camslot = QRscanner(passcodelist, camslot) # Runs QR-reader if rightcode: 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("Package dropped, 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") time.sleep(pauzedelay) # Time buffer print("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")