Introduction

My home had an old DSC security system installed but I never used it. I saw Snazzy Labs video on his home alarm, and wanted to do the same with my home. With IKEA releasing new Matter devices for a relatively low price, I could just add the new sensors. However, it would be nice to reuse existing hardware and remove the need of replacing batteries.

After some research, it turned out that my security system was too old and didn't support the Envisalink 4. I discovered the dscKeybusInterface on GitHub which is a library that allows DSC security systems to integrate with systems like Home Assistant, HomeKit, and more.

Day 1 (December 25, 2025)

Parts

I planned this project months ago, so I already ordered the following parts:

• LM2596S DC-DC step-down module
• 2N3904 transistor (bought a kit)
• ESP32 with USB C port
• MB102 Breadboard
• Pack of resistors:
  • 33kΩ
  • 10kΩ
  • 1kΩ

Software

The hardware aspect was the most intimidating part as I didn't want to short a part of the system and break something. So, I decided to start off with the software.

First, I started by downloading Arduino IDE.

I installed the DSC Keybus Interface library.

I then loaded the sketch for HomeKit-HomeSpan.

I plugged my ESP32 in and selected the board as a ESP32 Dev Board. I determined which port it was by unplugging and replugging the Arduino in and seeing which port reappeared.

In the sketch was the wiring needed to connect the ESP32 to the DSC security system.

I had an analog multimeter, so I ordered a ZT-109 from AliExpress. It seems to be the white label product for the ANENG AN8008 which was recommended online. I put the project on hold until the multimeter shows up as I don't want to adjust the step-down module with an analog measurement.

Other Solutions

I ended up swapping my system to a DSC PC1832 and PK5500 keypad which was supported by the Envisalink 4. I then used the Envisalink 4 to integrate with Home Assistant and HomeKit. This ended up being a much easier solution as I didn't have to worry about wiring and hardware issues. The Envisalink 4 also had a lot of features and was well supported by the community.

You can read more about it here.