LegacyGuard Wireless Extension (PIR wireless repeater)

Want to add new sensors to your wired alarm system... without running cables? LegacyGuard Wireless Extension is the system I designed to expand any wired alarm control panel by adding new sensors with no masonry work at all.

Why it's brilliant:

Zero masonry work: no conduits, no holes, no plaster or paint repairs
Compatible with any wired control panel: no need to replace anything, it integrates as a normal input
Add PIRs, NC contacts and special sensors: each slave manages the input you need, from a simple magnetic contact to a volumetric sensor
Perfect for already finished or renovated homes, exactly where work would be most expensive and disruptive
Extremely fast installation: usually just a few minutes per slave
Expandable over time, up to 4 slaves per master

The problem

How many times have you thought: "A sensor would really be useful here"... and then given up because running cables through the whole house is a nightmare? Visible conduits, holes in freshly painted walls, half a day of invasive work just to add a single magnetic contact on a window. The end result is always the same: you give up, and that point remains unprotected. A corridor without a PIR, a rear window without a contact, a technical room that nobody ever wanted to drill to run a two-wire cable.

How it works

The idea is as simple as it is effective: a Wi-Fi-based master module communicates with small slave modules (from 1 to 4 per master), which you can install exactly where needed, even several metres away from the control panel. Each slave connects to the sensor with just a few centimetres of cable (enough to reach the PIR or magnetic contact in the same box) and is powered by a small 12V plug-in power supply, with no need to run the control panel's bus line all the way there. From that moment on, the slave module sends the sensor status via Wi-Fi to the master, which translates it into a signal on the wired terminal connected to the control panel. For the control panel it is as if there were a traditional wired sensor: closed zone, clean contact, no difference. It believes it has a new wired input. You haven't run a single metre of cable. The complete project, with firmware, PCBs and schematics, is available on the project's GitHub repository.

Technical note on range

I tested this system in an apartment reaching 7 metres of distance from the master to the slaves.

System testability via Telnet (from smartphone)

The system is fully inspectable remotely without needing to connect the board via USB: simply connect with your smartphone to the master's WiFi network (your customised SSID) and open a Telnet session to 192.168.4.1:2323 with any Telnet app for Android/iOS (e.g. Termius, JuiceSSH). After authentication and entering the diagnostic menu (m), the following tests and information are available, all accessible on the move:

Hardware board reset (command 0): useful for forcing a clean reboot without disconnecting power
Firmware source file name (1): to quickly check which version is running
Detailed statistics (2): number of detected alarms, successful and failed calls for each slave
Extended diagnostics / tracing (3): can be activated on the fly to follow the internal behaviour of the firmware in real time
Continuous presence/absence scan (4): shows in real time which slaves are responding and which are not
Activation of Web OTA mode (5): to start a remote firmware update without opening the board
Board MAC address (6): required to request customised network credentials

This makes it possible to test the entire system (radio coverage, polling reliability, correct operation of each individual slave) directly from your phone.

Master display and LEDs

Even without opening the Telnet console, the master provides an immediate overview of the system status thanks to the OLED display (which shows in real time the synthetic status of each of the 4 slaves: present/absent, normal/alarm) and the two edge LEDs, which respectively indicate polling activity at each cycle and the network scan/mapping phases.

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