🚨 Raspberry Pi Security System

A home alarm built with a Raspberry Pi. An ultrasonic sensor detects movement, the Pi sounds a buzzer and records a photo and a 10-second video with the camera module, and the alert arrives on your phone through Discord.

_{Real photo of the build, edited with AI to remove the jumper wires so the components are easier to see.}

How it works

1. Press Play on the IR remote to arm the system: the status LED turns on and the current distance in front of the sensor becomes the reference.
2. The HC-SR04 sensor measures the distance about once a second. When something comes more than 3 cm closer than the reference, the alarm goes off:
   • the buzzer sounds for 1 second;
   • the camera takes a 1280×720 photo and records 10 seconds of video, converted from .h264 to .mp4 with ffmpeg;
   • a Discord webhook posts the time, the distance change, the photo and the video.
3. Videos over Discord's 8 MB limit aren't uploaded. The alert carries a link to a small Flask server on the Pi that streams them on the local network, protected by a password.
4. Press Play again to disarm. Every alarm is written to recordings/alarm_log.txt.

Some implementation details:

• IR decoding by hand: the remote's NEC signal is read directly from the GPIO pin by timing the pulses, without LIRC or any IR library.
• Threads: the remote and the sensor run in two threads, so the system can be armed or disarmed while it is measuring.
• One launcher: start_all.py starts the detector and the video server together and merges their output.

Hardware

• Raspberry Pi with a camera port, plus the Raspberry Pi Camera Module
• HC-SR04 ultrasonic distance sensor (with a voltage divider on ECHO: it outputs 5 V and the Pi's GPIO expects 3.3 V)
• IR receiver and an NEC remote
• Active buzzer
• LED with a resistor
• Breadboard and jumper wires

Wiring (physical pin numbers, GPIO.BOARD)

Pin	Connected to
7	Buzzer
13	IR receiver OUT
15	Status LED
16	HC-SR04 TRIG
18	HC-SR04 ECHO

Setup

The camera code uses the picamera library, which needs the legacy camera stack (Raspberry Pi OS Buster, or Bullseye with Legacy Camera enabled in raspi-config).

sudo apt update
sudo apt install ffmpeg python3-pip python3-picamera
pip3 install RPi.GPIO requests python-dotenv flask

git clone https://github.com/MCCProgrammer/RaspberryPi-Security-System.git
cd RaspberryPi-Security-System
cp .env.example .env

Fill in .env:

Variable	Description
DISCORD_WEBHOOK_URL	Webhook of the Discord channel that receives the alerts (Channel settings → Integrations → Webhooks)
WEB_PASSWORD	Password for the video links. The video server won't start without it

Running it

python3 start_all.py

Wait a couple of seconds, point the remote at the receiver and press Play. The terminal shows the distance readings and every alert sent.

The remote codes are in the Buttons list in securitySystemDiscord.py. Only ButtonPlay is used: change it there if your remote sends a different code.

Files

File	Purpose
start_all.py	Starts both programs and prefixes their output with [Motion] and [Flask]
securitySystemDiscord.py	IR decoding, distance measurement, buzzer, camera, Discord alerts and the log
recordings/video_server.py	Flask server that lists and serves the recorded .mp4 videos