Welcome to PhantomPilots.com

Sign up for a weekly email of the latest drone news & information

what does the can bus do?

Discussion in 'General Discussion' started by Suwaneeguy, Apr 16, 2014.

  1. Suwaneeguy

    Joined:
    Feb 19, 2014
    Messages:
    701
    Likes Received:
    22
    Will someone please explain just what the functionality and or purpose of the can bus is?
    Why and when would I need it?
     
  2. OI Photography

    Joined:
    Sep 23, 2013
    Messages:
    5,542
    Likes Received:
    17
    Location:
    Clarksville, TN
    It's the communication and power connection that lets you use accessories like an iOSD mini, grounstation data link, etc.
     
  3. ianwood

    ianwood Taco Wrangler
    Staff Member

    Joined:
    Jan 7, 2014
    Messages:
    4,929
    Likes Received:
    1,800
    Location:
    Lost Angeles
    CAN bus works kind of like an Ethernet network. It is common in modern cars. It allows all the different systems to talk to each other. Systems subscribe to each other's messages. For example, iOSD uses the CAN bus to get all the real-time flight data from the Naza. When the ground station is connected to the CAN bus, it sends control messages to the Naza.
     
  4. Gizmo3000

    Joined:
    Jan 25, 2013
    Messages:
    1,859
    Likes Received:
    2
    Location:
    Sherman Oaks, CA
    it's really more like USB ports on a computer. - every computer has a few USB ports, but if you want to connect more than that you need to buy a USB hub.

    All the DJI accessories use a Can Bus connector to connect to the PMU/NAZA.

    The PMU 2 only has a single Can Bus connector, so if you wanted to connect more than one device, you'd need to get the Can Bus Hub. (although the iSD mini has an extra port so you can connect another device to it)
     

    Attached Files:

  5. ianwood

    ianwood Taco Wrangler
    Staff Member

    Joined:
    Jan 7, 2014
    Messages:
    4,929
    Likes Received:
    1,800
    Location:
    Lost Angeles
    It may seem like USB because that is how DJI packages it. However, you can add as many items as you like to the bus without any hubs, heavy cables, etc. doing only basic soldering. The basic topology of a CAN bus is dead simple:

    [​IMG]
     
  6. Suwaneeguy

    Joined:
    Feb 19, 2014
    Messages:
    701
    Likes Received:
    22
    Thanks for the images. That helps explain the can bus role.
    Now if they could just put it all into one neat little box.
     
  7. shaunmed

    Joined:
    Mar 9, 2014
    Messages:
    96
    Likes Received:
    0
    should the can bus be removed when using lightbridge?
     
  8. sar104

    Joined:
    Mar 22, 2014
    Messages:
    1,265
    Likes Received:
    245
    Location:
    Los Alamos, NM.
    I removed the cable and the connector on the leg, if that is what you mean. Saved a few grams.
     
  9. shaunmed

    Joined:
    Mar 9, 2014
    Messages:
    96
    Likes Received:
    0
    yes i mean the cable leading to the can bus on the leg and its connection to the main board.

    do you have a lightbridge? can you get it to work? Ive tried everything and i cant get my radio (DX6i) to communicate with the phantom through the lightbridge. any help is greatly appreciated
     
  10. sar104

    Joined:
    Mar 22, 2014
    Messages:
    1,265
    Likes Received:
    245
    Location:
    Los Alamos, NM.
    Yes - mine seems to be working fine. I'm using a Futaba 14SG. So nothing works? What color are the status lights (control and video) on the air unit when you power everything on, is the ground unit status light blinking or solid, and what does the OSD show for connection status?
     
  11. shaunmed

    Joined:
    Mar 9, 2014
    Messages:
    96
    Likes Received:
    0
    all the lights are solid green including both air unit lights and solid green ground unit light. All the telemetry on the LB app is reading correctly except i have an error in the botom right corner saying
    [​IMG]
     
  12. sar104

    Joined:
    Mar 22, 2014
    Messages:
    1,265
    Likes Received:
    245
    Location:
    Los Alamos, NM.
    Flashing yellow lights on the Phantom? What values to the control and video signal indicators (OSD top right of center) say? You are in Naza mode I assume.
     
  13. shaunmed

    Joined:
    Mar 9, 2014
    Messages:
    96
    Likes Received:
    0
    the control signals on the osd/ telemtery read 100% and 98%

    I have tried both Naza and Phantom mode with same result.
     
  14. shaunmed

    Joined:
    Mar 9, 2014
    Messages:
    96
    Likes Received:
    0
    the control signals say 100%.

    There are flashing yellow lights on the rear LED's of the P2.

    I have tried both Naza and Phantom mode on the Asst Software.
     
  15. sar104

    Joined:
    Mar 22, 2014
    Messages:
    1,265
    Likes Received:
    245
    Location:
    Los Alamos, NM.
    My guess is that your radio is triggering failsafe mode on the Phantom - I can reproduce exactly what you describe by switching to FS. Have you checked in the Phantom Assistant to see what the U channel input looks like? I had to reprogram the endpoints on the Futaba for the switch that I assigned to the U channel - unadjusted it was triggering failsafe.
     
  16. shaunmed

    Joined:
    Mar 9, 2014
    Messages:
    96
    Likes Received:
    0
    this is what it shows
    [​IMG]
     
  17. shaunmed

    Joined:
    Mar 9, 2014
    Messages:
    96
    Likes Received:
    0
    How do i get out of failsafe mode?

    [​IMG]
     
  18. sar104

    Joined:
    Mar 22, 2014
    Messages:
    1,265
    Likes Received:
    245
    Location:
    Los Alamos, NM.
    Right - it's in Failsafe - that's the problem. First of all I would switch back to Naza mode, then check your switch position on the radio (it seems to be at the wrong end of the throw anyway) and then adjust the endpoints so that it falls correctly into the 3 positions. I don't have FS set on that switch anyway - I use a different one as you can see.

    [​IMG]
     
  19. shaunmed

    Joined:
    Mar 9, 2014
    Messages:
    96
    Likes Received:
    0
    moving any of my switches (gear, elev, flap, ail, rudder) doesnt make the U-channel slider move at all. Do I have to configure something on the Dx6i (as in a new model type, mix etc?)
     
  20. shaunmed

    Joined:
    Mar 9, 2014
    Messages:
    96
    Likes Received:
    0
    also the asst software says the exact same thing even when i dont have the radio connected to the LB at all

    I think youll find you can get yours to act the same way perhaps if you disconnect the radio as well?

    its as if the LB is getting no signal from the radio whatsoever, or not transmitting any info. is there some special other setting on the DX6i that i have to program?