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I aim to be able to copy my garage door opener onto another device, but for that to be doable I first have to be able to recreate the radio signal that is sent from the garage opener.

Is there any way to read the signal of a radio transmitter and be able to "store it" for later use? That is, reading the signal and implement it into my own software. So I recreate the signal from my Pi whenever I want to open the garage door.

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2 Answers 2

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The problem you're likely to have is that just about all modern RF remote controls will use a rolling code, so if you record and playback the same code it won't work because it will expect the next sequence number. It's meant to avoid a third-party being able to easily record and play back the code.

Your only practical option might be to get another remote control from the original manufacturer (or maybe you already have a spare?) and control that using the Raspberry Pi. A simple way might be to connect mechanical relay contacts across the button contacts to simulate it being pressed.

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  • \$\begingroup\$ What I want to do is create my own spare so I don't have to purchase one. It's fun to have a project! I want a raspberry pi that I bring in my car to open the door with a radio signal. It's a garage for about 10 people, can a rolling code be used even though there's more than two transmitters? But my first problem is still, how do I go about sniffing and reading the signal/code in the first place? \$\endgroup\$
    – tskjetne
    Commented Mar 27, 2016 at 13:59
  • \$\begingroup\$ @pewpew One way to work out if it's a rolling code would be to look at the receiver or the manual for it and see it if has some sort of "learn" button to program new remotes, they do support multiple remotes I think mine can learn up to 10. I'd look into that first - most new ones are and recording it won't do any good if it is one. \$\endgroup\$
    – PeterJ
    Commented Mar 28, 2016 at 10:23
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It depends on the garage door opener.

If it uses a 433 (also referred to as 434) MHz or 313 MHz transmission frequency you can buy an inexpensive radio module (E.g. a 434 module) and sniff the data.

If it doesn't use a rolling code (one which changes after each use) then you can replay the data.

If it uses Manchester coding you can try my Raspberry Pi example code at http://abyz.co.uk/rpi/pigpio/examples.html#pdif2__433D

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  • \$\begingroup\$ Is there any way to find a pattern in rolling codes? I'm gonna assume no, cus if so it would be fairly easy to break? \$\endgroup\$
    – tskjetne
    Commented Mar 27, 2016 at 14:01
  • \$\begingroup\$ And.. how can I know what sort of coding is used? \$\endgroup\$
    – tskjetne
    Commented Mar 27, 2016 at 14:01
  • \$\begingroup\$ You'll have to view the data being received with a logic analyser or similar. On the Pi you can also view the data with my piscope program. If you get a screen shot someone will probably recognise the data format. \$\endgroup\$
    – joan
    Commented Mar 27, 2016 at 14:15

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