Intruder detection system

Do you have any data that would cause damage if it fell into the wrong hands? Or do you wish to know who enters a specific place when you're not present? Well, you can now easily answer these questions by building your own intruder detection system!

As mentioned before, this project uses an ultrasonic range sensor for the GrovePi and a PiCam to take pictures if any movement is detected by the ultrasonic ranger. Connect the ultrasonic ranger to port D4 of the Grove Pi, the buzzer to D5, the status LED to D3, and the Pi Camera to the port provided on the Raspberry Pi as learned in Chapter 4, Working with Webcam and Pi Camera. Following the theme of the book, we will first look at the whole code, and then learn what each statement does, line by line:

import picamera
import grovepi
from time import sleep

camera = picamera.PiCamera()
counter = 0
led = 3
buzzer = 5
ultrasonic = 4

while True:
    try:
        if grovepi.ultrasonicRead(ultrasonic) < 100:
        print...