This is a project to add additional ‘smart’ functionality into a thirty year old (1993) but fully functioning (and reliable) alarm system.
Existing alarm system
Gardiner Gardtec 800 series alarm, powered by 240v stepped down to 12v DC. With LED and LCD extension display/key pads.
4 wire detectors and 8 zones - with Texecom dual technology PIRS, a magnetic switch and a shock detector. Bell/Strobe unit and extension speakers.
“Smart” functionality added
Set and Unset of alarm using a remote control or via a keycode entered into a local (for security reasons) webpage. The webpage is accessible when outside the LAN by using a VPN server running on a Raspberry Pi. The webpage is redirected from a local domain (alarm.domain.com).
Live status of system (unset, set or alarm triggered) via the internal LED, a webpage and an email notification.
Remote updateable of firmware using Elegant OTA.
Operation
Wireless key remote pressed for 4 or more seconds > Alarm set if previously unset or unset if previously set.
Correct passcode entered into web form > Alarm set if previously unset or unset if previously set, Web page updates after countdown period (exit time of 36 seconds or 7 seconds on entry).
Alarm unset > After countdown period, webpage displays green box and button shows “SET”, Email sent stating Alarm has been unset
Alarm set > After countdown period, webpage displays blue box and button shows “UNSET”, Email sent stating Alarm has been set, LED is ON
Alarm triggered > Webpage displays, ** ALARM TRIGGERED **, red box and button shows “RESET”, Email sent stating Alarm has been triggered, LED FLASHES
Module
ESP-32S Development board utilising Wifi, three inputs, two outputs, internal LED, email server and over the air (OTA) firmware update.
Software written in Arduino IO (C++) and based on existing templates – See acknowledgements. Software was based on published projects and modified to suit. It was tested using components on a breadboard.
Hardware
Interface – Veroboard with MP2307 12v to 5v DC/DC converter, 2NAAAAA npn transistor, six resistors (6.7K (2), 10K (2), 1K and 330 Ohm, 817 Optocouplers (3); 433mhz relay module receiver, two remotes and a 10K resistor.
The interface is fitted inside a small plastic wallet and placed inside the alarm case along with the wireless remote receiver.
The ESP-32 is mounted on veroboard and placed in small, clear rectangular box. It has been mounted adjacent to the alarm panel.
Alarm Panel Connections (5)
- 12v
- 0V;
- Key switch in biased mode (12v when closed for a minimum of 1 second will set/unset the alarm)
- SW latch (0v if alarm unset, 12v if set)
- Bell (0v if triggered, 12v if not)
ESP-32 Connections (7)
- 3.3v
- VIN (5v)
- 0v
- GPIO22 (wireless remote)
- GPIO19 (alarm state – set or unset)
- GPIO23 (set/unset the alarm)
- GPIO18 (bell triggered)
Issues/comments
Location of interface - It was decided to keep the interface separate from the ESP-32 in order to keep the 12v alarm panel wiring discreet from the 3.3/5v wiring of the ESP-32.
Wireless remote random operation - The wireless remote control receiver suffered from random triggers (probably from stray RF) resulting in the alarm being set/unset by itself. In order to resolve this, the output from the remote relay was fed into GPIO22 of the ESP-32 and a time condition set (currently 4 seconds but adjustable) before the state was changed. A better solution would be to use a different remote relay which doesn’t suffer from random triggers and could be connected directly (it outputs 12v) to the key switch.
Wifi receiver of the ESP-32 – A powerline adapter and unused router have been used to provide wireless access to the garage. The following site suggests ways to improve the Wifi reception of the ESP module - https://www.hackster.io/rayburne/esp32-development-board-official-vs-clone-7f4ff7. I also tested a board with the same layout but from a different source. It looked virtually identical (apart from being labelled with a DOIT logo and www.boltom) but was far more sensitive and displayed SSID’s the other board did not pick up.
Elegant OTA - This is a beautifully crafted and simple way to update ESP-32 firmware without having to disconnect the module and connect to USB. I did have problems updating scripts when the Wi-Fi connection was less than optimal.
