Security camera with PIR and alarm

Parts in this circuit

Wiring, pin by pin

Red = 5 V, orange = 3.3 V, black = GND, other colours = signals. “Pin” is the position on the 40-pin header; the GPIO number is what the code uses. Power the Pi from a 5.1 V supply and wire with the power off.

Python code (gpiozero)

from picamera2 import Picamera2
from gpiozero import MotionSensor, Buzzer, LED
from signal import pause
from time import sleep

cam = Picamera2()
cam.configure(cam.create_still_configuration())
cam.start()
sleep(1)

pir = MotionSensor(4)
alarm = Buzzer(23)
lamp = LED(17)
shots = 0

def intruder():
    global shots
    shots += 1
    lamp.on()
    alarm.beep(on_time=0.2, off_time=0.2, n=3)
    cam.capture_file("intruder%d.jpg" % shots)
    print("Intruder! Photo", shots, "saved")

def quiet():
    lamp.off()

pir.when_motion = intruder
pir.when_no_motion = quiet
print("Armed. Click the PIR dome to wave a hand.")
pause()

How the code works

• The PIR is cheap and low power. It wakes up the rest of the system.
• intruder() runs when the PIR sees motion: lamp on, three beeps, one photo.
• The global counter makes each photo name different (intruder1.jpg, intruder2.jpg).
• The photo appears in the box under the console.

Parts to buy

The links open a search on each store, so you see what is in stock today. Check the model, voltage and price before you order.