Discussions

Pixhawk with DJI Lightbridge

Posted by Chris L on October 30, 2015 at 8:36pm

Has anyone been able to configure a Pixhawk to work with a lightbridge HD link?

I'm able to get the Lightbridge control signals to the pixhawk but I've yet to figure out how to set the FailSafe. When I turn off the RC controller, the lightbridge air module continues to output the same S.Bus channel signal levels.

From talking to others I've found out that Lightbridge outputs the fail-safe "flag" in the header or footer (I'm not sure which) of the S.Bus signal (not the normal PPM channels like the pixhawk is expecting). Can anyone confirm this is true and if so, how can I map the DJI Lightbridge failsafe signal to the Pixhawk's failsafe.

Thanks!

You need to be a member of diydrones to add comments!

Join diydrones

lightbridge, pixhawk

Email me when people reply –

Replies

- - - - andreas kellermann > Andre K. December 11, 2015 at 2:19pm
        
        USB 2.0 is 10Mbit/s isn`t it? Recommended bitrate for 720/1080p is about 15/25Mbit/s for good quality stuff. So it might be a problem. I found the quality on usb worse than on a direct hdmi screen but I`ve never tested it objectively.
        
        Also, the smartphone/tablet on the other hand has to convert the data into a playable video format which uses a lot of processing power so you`re right depending on the hardware there might be more or less lag which I assume is what you mean with poor hardware.
        
        Andre K. > andreas kellermann December 11, 2015 at 2:38pm
        
        correting these misconceptions is off topic, so this is my last post:
        
        USB 2.0 is 480Mbit, and that's not the limit but actually *wirelessly* transferring even a quarter of that over some distance is the real limit here.
        
        Also , an typical (not high end) Android phone can play 1080p at pretty high bitrate like 3.8GB file for 120min movie just fine, because most devices have hardware accelerated decoding of most essential video codecs. So the phone/tablet is not too slow to decode that at all, also, remember that many devices now capture and play 4K just fine.
        
        the end :)
Developer

Linus December 8, 2015 at 11:43am

What about the Connex from Amimon ? http://connex.amimon.com/

Any experience or opinions ?
- Olivier > Linus December 8, 2015 at 8:59pm
  
  It's awesome, love it. 1080 60 fps, works right out of the box. Mavlink telemetry/osd support via serial for Pixhawk. Ridiculously low latency.
  
  Same technology as Teradek (Aminon), yet a fraction of the price and specifically targeted for UAV. One thing some have complained about (rarely) is that it's software limited to 1km. Not a big deal imho since it can barely go past that, (LOS), anyways. Also loss of connection if it happens is rather brutal ... Very little warning and no "graceful" degradation, more like blue screen.
  
  Watching on a large screen TV display video fed from a decent HD camera, it feels like National Geographic ...
  - Developer
    Linus > Olivier December 9, 2015 at 2:25am
    
    Olivier thanks for your comment, i do really like to hear that!
    
    I was an early adopter and not impressed by the Lightbridge 1, had to send it back twice before it started working barely with a Z15 Zenmuse.
    Thought i was just unlucky but at that time even the software was really in beta stadium.
    
    For the big money spent i want something better or it being hardware compatible.
    
    One step closer to getting rid of DJI entirely.
andreas kellermann December 7, 2015 at 2:04pm

Hi Chris

Yes, I fly a Pixhawk Skywalker and a Dropix tricopter for about half a year with a DJI Lightbridge. Works really well and RC link is at least as good as a standart 2.4ghz transmitter.

You set the failsave in the DIJ Lightbridge app to your values. To test them you have to arm Ardupilot first (secure the props...!).
- Chris L > andreas kellermann December 8, 2015 at 4:30pm
  
  Thanks for the response!
  
  I've figured out that I need to use the Android App, The Iphone app is different and wont' let you do this (at least on the LightBridge 1). I'm planning on getting an Andriod device soon so I can try this (I only have an Iphone at the moment).
  
  In the DJI Lightbridge App, does it let you configure which channel the FailSafe is sent out on? How does the Pixhawk get/interpret the light-bridge's Failsafe signal?
  
  Thanks,
  
  Chris
  - Elvin Sosing > Chris L December 8, 2015 at 5:21pm
    
    Hi Chris,
    
    How did you connect the lightbridge RX to the Pixhawk? Is there a special cable bought online or did you DIY a cable for it?
    
    Also, if I'm using let's say a Futaba 12fg Tx, can I still use all of its channels even when connected to the lightbridge (e.g. retract landing gear, switch flight modes on APM and operate gombal?)
    
    Thanks,
    
    Elvin
    - Chris L > Elvin Sosing December 11, 2015 at 7:29am
      
      No special cable. Just connect the "DBUS" cable output from the Light-bridge Air Module to the Pixhawk's SBUS input ("RC In") cable. The cable came with the lightbridge. From the Mission Planner app I can see the 8 channels coming through.
Blair W Hunter December 5, 2015 at 10:11pm

I would also like to figure out how to rig a lightbridge like system onto a non-dji UAV.

We've been using dji exclusively so far, and are hoping for some more flexibility than diu can offer. Now that we've used lightbridge though, don't know if we can go back. It's pretty sweet, especially for our applications (looking at baby trees close-up, from far away).