I’ve got electric garage doors. You may remember that from an earlier blog post where I managed to close the garage doors on my car before fitting sensors. Well now I’ve gone one better and made it so that I can open and close my garage doors with my phone.
It all began in January 2023 when I bought some spare remote control garage fobs, synced them up with my garage doors and then ripped them apart. I used an oscilloscope to determine which pins on the chip went high when I opened and closed the doors and then I delicately soldered some wires to the chip and then hooked them up to a raspberry pi [ of course ]
Now, my electronics has always been a bit rubbish but I knew that the raspberry pi GPIO pins ran at 3.3 volts. Also, I knew that the battery powering the fob was running at 3.3 volts so I just made a direct connection. It worked first time. I was amazed that I could open my garage from the end of the garden. The remotes had never been that powerful before.
Then came a problem. It stopped working after the first go. It confused me for a while…quite a while…about three remote control key fobs at £20 a pop. I thought maybe I’d damaged the processor when soldering so I again hooked up my oscilloscope to see which side of the switches were ground and I hooked my wires up to them to keep some distance away from the delicate microprocessor. Again it worked for a while and then stopped working.
One day I had an epiphany. “It’s the current! The signals from the raspberry pi are blowing up the processor”. So with a really simple fix of dropping a 55k resistor between the pi and the remote control everything worked well.
At this point I only hooked up one door and I could just make it go up or down as I hadn’t soldered up the stop button. Fast forward a few months and I bought another remote control for the second door, ripped it apart and soldered up all three buttons [ up, down and stop ] and whilst I was at it I took the first remote control and soldered the stop wire onto that too.
The finished item looks rather like an IED
Then of course there is the mobile phone app which powers the whole thing and the python based flask server running on the raspberry pi that does all the real work of driving GPIO pins and such