I’ve decided to completely rebuild my DIY alarm system.

• Mean Well UPS supply instead of C-TEK charger
• Bigger battery in dedicated cabinet
• Arduino Mega as core, Raspberry Pi only as MQTT relay
• End-of-line resistors

The biggest change is undoubtedly moving the alarm state machine and all logic from the Raspberry Pi to an Arduino Mega. There are three main reasons for this move:

• It’s fun and I’d like to work more with the Arduino
• The Arduino Mega has 16 analog inputs, making it possible to use end-of-line resistors
• An alarm system needs to be stable — not crash, hang or get a corrupted SD card

I’ve been thinking about end-of-line resistors since I first got started, but the Raspberry Pi doesn’t have any analog inputs. Initially I thought of using the Arduino Mega as an I/O interface device, but as I got started I figured why not let it do more.

So #RPiSecuritySystem is now #DIYAlarmSystem.

The keypad, or alarm panel, is an important part of a security alarm system. When I first got started building mine — I settled for a cheap and simple Zigbee keypad.

I’ve since replaced it with a better, and more advanced device. Let’s have a look…

Quick recap: I’m building a DIY security alarm using a Raspberry Pi, hardwired PIR sensors, and MQTT integration with Home Assistant.

Hello again — it seems to be close to a year since I last managed to get some words published on this blog. And almost three years since I last wrote about my Raspberry Pi security alarm project 😮

But the project is still alive and well. We use it every night and whenever we are away, and it just works 😃 Development usually happens in bulk, with very little happening in between.

In November last year — I started building a DIY security alarm system, using a Raspberry Pi as the controller. My plan was to make a self-sustained system, using proper alarm hardware — like PIR sensors and sirens.

Integration with Home Assistant would be an add-on, not a requirement. I wanted the system to be as redundant and fault-tolerant as I could make it.

This is a pretty long story, with some twists and turns — let’s get into it 👇

Using a few cheap sensors, a wireless keypad, Zigbee2MQTT and Home Assistant; I was able to get a basic security alarm up and running during a free afternoon 🙂