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hacking lightbridge

Discussion in 'DJI Lightbridge' started by gaucho, Apr 14, 2015.

  1. gaucho

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    Is it there a way to hack the lightbridge?
    let's share some ideas.
    Is it there other tool available, apart the assistant?
    i connected via usb and then i opened a terminal on the virtual serial port created by the lightbridge driver. I found that the lightbridge sends readable ascii strings. Is it there some commands that can be issued to the lightbridge in order to get information from it?
    actually i get only 4 parameters but of course with the proper commands it is possible to receive all the lightbridge information, like the assistant does.

    moreover may be that connecting to the other usb port with a male-male usb cable it is possible to decode the used protocol in order to develop our applications.

    EDIT: in example: i think that actually it is not possibile to have a "follow me" function by using the lightbridge. but if we discover the used usb protocol, we could connect the audio cable and the usb cable to the smartphone and develop a app able to realize the "follow me" function.
     
    iowahill and Rodri Serra like this.
  2. CityZen

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    You can run USB Protocol Analyzer software on the PC to intercept all the USB communication as the device talks to the Assistant software. There even seems to be some free software to do this, though I have no experience with this particular program (freeusbanalyzer.com).
     
  3. gaucho

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    the analysis on the upgrade port with the suggested tool was not satisfatory. I will try again with a USB MALE-MALE cable in order to check with a notebook the port commonly connected to the smartphone.

    Moreover I started a android library for the PPM encoding in order to create a joystick on android.
    The joystick app will be able to control the drone by connecting an audio cable between lightbridge and the smartphone.
    This is the discussion about the library: http://stackoverflow.com/questions/29715866/android-ppm-audio-library
     
  4. ianwood

    ianwood Taco Wrangler
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    There's a good PPM lib for Arduino called PulsePosition. https://www.pjrc.com/teensy/td_libs_PulsePosition.html

    Do you know if any telemetry is passed through the USB? GPS position, heading, altitude, etc. You could build an autopilot with that.

    I want to hack the air unit and find a way to pass data through the downlink. I am guessing that LB uses the audio channels to carry data but I doubt it uses all of them. It would be a tough hack. I have a Teensy and a CAN bus transceiver that reads a lot of data off the bus and records it to SD card. I would love to use the downlink to transmit it to an app.
     
  5. gaucho

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    Yes, of course i wish to know if those info pass the bridge. Actually i have no confirmation.

    Last week one of my lightbridge fallen in the river water (with my phantom).
    I had to completely open the flying part of the lightbridge to allow the water evaporation.
    I found that the internal chips are covered by some material, resin. So it is not possible to read the chips producer and model.

    Note1: the same resin is also on the naza controller.
    Note2: the lightbridge now works again, the only damage to the entire system is to the battery of the phantom.

    Note3: the crash in water was due to a video stream interruption while i was passing under a bridge. I was doing a fpv flight at a distance of 20 meters. I was on the bridge and the phantom under the bridge.
     
  6. gaucho

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    I tried reverse engineering (decompile) of the Lightbridge app but I can't understand how to receive the telemetry from the Lightbridge.
    Here annexed you can find the app sources. Can you help me?
     

    Attached Files:

  7. gaucho

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    I decompiled the Lightbridge app but I'm not able to understand how to receive the telemetry data.
    Can you help me? Here annexed you find the original apk and the decompiled sources.
    It is important to note that the Lightbridge app, like the vision app, uses a native library named libdjivideo.so
    You can find the .so library by extracting the apk like a zip file.

    Edit: the apk is too much big to upload it on this forum, I uploaded it on a file sharing server, this is the link to download it: http://www.2shared.com/file/t38dwKZe/pkg.html
     

    Attached Files:

    #7 gaucho, May 20, 2015
    Last edited: May 20, 2015
  8. ianwood

    ianwood Taco Wrangler
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    Can't download the ZIP.
     
  9. gaucho

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    i do not understand. i downloaded both zip files without problems. please try another browser and then better detail the problem.
     
  10. ianwood

    ianwood Taco Wrangler
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    I got it. Will have one of my Android guys take a look at it next week.
     
  11. Rodri Serra

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    I have interest in use DJI Lightbridge with Pixhawk control board. Do you know if it is possible ?
     
  12. gaucho

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