How I Built a DIY Alarm with Raspberry Pi Pico

Repository with code and schematics:
https://github.com/andruhon/pico-dog

If you've got security cameras tied to cloud services, you'll know the frustration – push notifications arrive with latency, footage takes ages to load, and by the time you realise someone's at your door, they're already gone. I needed something that reacts instantly to motion at my porch, warns potential intruders that they're being monitored, and gives me immediate awareness when someone's about.

Enter the Pico Dog – a simple yet effective motion-activated alarm system that detects movement with a PIR sensor and plays a dog bark sound when it's dark outside. Unlike cloud-based systems, this responds immediately. It's already repelled a few people poking around my porch at night, and it works brilliantly alongside my security cameras.

As a bonus, I've created a Halloween edition that plays spooky sounds for trick-or-treaters – with the ambient light detection disabled, it entertains kids coming to grab some lollies.

The system is beautifully simple. The Raspberry Pi Pico monitors a PIR (Passive Infrared) motion sensor continuously. When motion is detected, it checks the ambient light level using a VEML6030 light sensor. If it's dark enough, it triggers an audio file through a PAM8406 amplifier connected to dual speakers, playing a convincing dog bark sound.

The PIR sensor detects infrared radiation changes – essentially, it picks up the heat signature of moving objects. The HC-SR501 module has two potentiometers: one controls sensitivity, and the other sets the timeout delay. I've found that turning both counterclockwise quite a bit prevents false positives from things like wind-blown branches or small animals.

The light sensor ensures the system only activates at night. There's no point barking at the postie during the day, but anyone lurking around your porch after dark will get an immediate audio warning.

0:00 Intro
0:26 Intruders! Motivational video for DIYers
0:33 Quick demo
0:58 Problem statement
1:16 Studying Raspberry Pi Pico
1:41 Building the Alarm: Components
2:23 Building the Alarm: mpremote for Micropython, how to enter bootsel mode to flash the controller
3:46 Building the Alarm: Playing Audio from Raspberry Pi
5:10 Building the Alarm: Passive Infrared Sensor to detect motion
7:23 Building the Alarm: Measuring ambient light
8:23 Building the Alarm: First test
8:28 Building the Alarm: Audio wistling and howling problem
10:17 Building the Alarm: Assembling everything together
12:50 Building the Alarm: final tests
13:49 Acknowledgments

Видео How I Built a DIY Alarm with Raspberry Pi Pico канала andruhon