Garage door open warning

Part #11 of the "Roger Writes" series - January 2024


We have a driveway down the side of the house, with a separate garage, but it very difficult to see the garage door from the house. You'd have to peer almost sideways through one of the back windows. So quite a few times we have left the garage door open (for overnight and longer).


I wanted some warning lights in the house, that would turn on while the garage door is open, and turn off when the door is closed.


I put one of the burglar alarm window switches at the top of the garage door to detect if it was open.

I used a PIC to detect the switch state and send the RF codes when the switch changes.

When the switch goes from closed->open, the PIC sends the "socket on" signal, for open->closed the "socket off" signal is sent.
To avoid missed signals, the signal is repeated a few times, and then again after 1,5 and 10 minutes.

I've got 3 of the recievers around the house, with a nightlight in them (with the light sensor covered with some foil, and white tape).


RF Codes

I've done quite a bit of low level remote control hacking using PICs, and decoded many RF remotes over the years. So set up a 433MHz receiver connected to one of the cheap USB logic analysers.
I was careful to find some remote sockets that have separate on and off buttons (not just a toggle). After grabbing the traces a few button presses, a pattern emerges.
With some simple coding to mimic the remote control, and then it's time to test.


I could use sleep mode, with wake on change, and a bunch of other low power things, but in the end I have a permanent 12V power supply on, so just used a 78L05 to generate the 5V for the PIC and Tx module.
In in addition to getting notificactions in the house, I use a 12V relay directly on the switch to control a 5 meter string of white LEDs, so we get decent lighting in the garage that turns on and off with the garage door.


Here is the PIC code for the Energenie and lightwaveRF RF code. Garage door code and headers

The Roger Writes series

I research / dabble with lots of things, and figured that if I write my notes here, I can quickly reference them, also, sometimes, they are useful to others!
Here is what I have so far:

This page was lasted updated on Sunday, 28-Jan-2024 15:39:49 GMT

This content comes from a hidden element on this page.

The inline option preserves bound JavaScript events and changes, and it puts the content back where it came from when it is closed.

Click me, it will be preserved!

If you try to open a new Colorbox while it is already open, it will update itself with the new content.

Updating Content Example:
Click here to load new content