Reverse engineering a cheap LED message marquee

[Hugo] went all out when sharing his findings while reverse engineering this small LED marquee. He purchased the 29×7 LED matrix for under $12 but was surprised to find that the USB connector wasn’t a standard type and didn’t come with a cable. He first soldered a standard connector in place and then set out to make the device do his bidding (translated).

What he accomplished can be seen in the video after the break. He can now connect to the device via a USB cable, sending it new messages and adjusting the speed at which it scrolls. He can also adjust the spacing between letters, reverse the scrolling direction, read the on-board buttons, and write the settings to the device’s EEPROM. This is all thanks to some alternative firmware that [Hugo] wrote for the ATmega88. You can download a copy of that code from the wiki page he put together (translated). We really appreciate the time he spent putting that page together. The wealth of information he gathered during the hacking process serves as an example of the best way to share your projects with the world.

27 thoughts on “Reverse engineering a cheap LED message marquee

  1. From what I can tell he’s Not actually connecting over a USB cable. Just Serial. He mentions it could be possible with V-usb and i agree, with some modifications I think it would be very possible.

    1. Hi How did you modify the micro USB . Cable connection details will help me.
      how can i send you the photo

      My Badge contains the Microcontroller U1



      Best Regards

      1. I don’t think I can help much without having one in my hands or at least additional details. Generally the protocols are pretty simple a few command bytes followed by the message(s) and possibly a checksum and final command byte(s). Most all of them use a simple serial interface, you’ll notice that one of mine had a USB connector, but was in fact just plain serial, perhaps yours is similar.

  2. A while back I modded one to run as a winamp display:

    Did some port sniffing. Turns out the control signals are super easy to use. First send 7 (if memory serves me) characters which relate to the speed of the display, then after that just send your message in to be displayed in ordinary ascii.

    Mine uses a ir led on the end of a serial cable to talk to it. This made it easy to sniff. There are still wirelessly programmable ones like this available which work the same way but use usb cables instead. The led signals on these are still the same so all you need to do is add your own ir led to the tx pin and gnd pin on a serial socket.

    Writing your own software for it is extremely easy. Will dig up the vb source code if anyone wants it.

  3. I got one of these from Tesco a while back. Massive disappointment in that it drained the CR2032 battery even when it was turned off and the disc with the software on was scuffed and not available online. (since it was an end of line clearance item there was little point or chance of a replacement)

    Definately going to have to take a look at this guy’s work. I might be able to salvage it after all.

  4. Hi thanks for the link… how many days/weeks/months does it arrive in the US? do i have to pay extra for taxes and stuff?


  5. I found some on eBay, bought 2 on 21-May, received on 28-May. Not exactly the same as on this article (button layout is different), but came with USB adapter/cables, extra batteries and driver CDs. About $12.

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