How to hook up my radians to my MK's GR24??

Discussion in '3 Axis Gimbal' started by Ben Freedman, Jan 26, 2013.

  1. Ben Freedman

    Ben Freedman Member

    Joined:
    Jan 11, 2013
    Messages:
    119
    Likes Received:
    1
    Hey, John...

    That's got to be it... So, with the Radian attached but unpowered, the resistors are bringing down the voltage to the extent that the MK cannot see the RX. When powered, the Radians are no longer bringing down the voltage, so the MK can now see the RX...

    Quite frankly, this seems like not a great setup to me. I may fly this once or twice as a test, but I've now ordered a 2nd receiver (GR12) to add to the gimbal, which I will bind to the same TX as the main RX (GR24)....

    Would you agree that's a better solution?

    Best,

    Ben
     
  2. John Cunningham

    Joined:
    Jul 5, 2012
    Messages:
    183
    Likes Received:
    13
    Ben : absolutely. If you lost power to the Radians then you will also lose control of the aircraft.

    You could experiment by adding an extra resistor in line with the Rx signal to the Radian : maybe 1K ohms or so. However, if you can't scope the signal to verify the peak value, you might be in logic 'no mans land'.

    I may be wrong, but I thought the MK ran the system at 5 volts because they overclock the cpu. If this is so, the minimum voltage for logic-1 rises. As many other RC modules put out 3.3v or less, this may be the main reason why a small voltage drop may stop it working.
     
  3. Andy Johnson-Laird

    Andy Johnson-Laird Administrator
    Staff Member

    Joined:
    Jul 31, 2012
    Messages:
    10,351
    Likes Received:
    1,160
    Reading this with my "I knew getting a EE would have been useful" glasses on, John's saying that yes, there is a good chance that a powered off radian will pull down the signals as you found Ben.

    As you say, the dodgy part about this is the gimbal battery is now made flight-critical. Lose it and you lose control.

    I will try and hook up my scope in the next few days, but I'm behind schedule on my next DVD production for QC so I can't promise an answer quickly. Does anyone else have a scope, Radians, GR24 and (most importantly) time to try it?

    Andy.
     
  4. Gary Haynes

    Gary Haynes Administrator
    Staff Member

    Joined:
    Jul 6, 2012
    Messages:
    5,211
    Likes Received:
    460
    Quick update. Got in a several flights with the dual receivers and it works fine. Probably the best, safest solution.
     
  5. Carsten Poulsen

    Carsten Poulsen New Member

    Joined:
    Sep 23, 2012
    Messages:
    8
    Likes Received:
    1
    I just changed my setup from a dual operator (Tx) to single by only using MX-20. This with only one receiver GR-16 Sum to the Mikrokopter FC and PWM direct out to the radians. It works very well.

    In my previous setup with MX-20 transmitter controlling the MK electronics on my Cinestar 6 and the MX-12 controlling the camera 2-axis-gimbal with radians - I two time saw a 100% jam of my MX-20 telemetry feedback during flight – the display went totally blank, but to my luck the controls worked for a safe landing. (That scared me a bit, so I changed the setup to eliminate potential telemetry conflicts on the Hott system)
    I attached my MX-20 switch overview for inspiration to the forum, all channels are now in use in my setup.
    -- Carsten
     

    Attached Files:

  6. Jeff Scholl

    Jeff Scholl Distributor

    Joined:
    Jun 29, 2012
    Messages:
    240
    Likes Received:
    50
  7. Steve Maller

    Steve Maller UAV Grief Counselor

    Joined:
    Oct 30, 2012
    Messages:
    3,979
    Likes Received:
    807
    Thanks for the diagram, Jeff! So you're not using a separate battery for the 2-axis? Most folks seem to agree that it's better form to leave the PDB and the mains to run the flight-related stuff and leave the photo/video stuff to a separate, isolated power system. I'm curious to hear your thoughts.
     
  8. Andy Johnson-Laird

    Andy Johnson-Laird Administrator
    Staff Member

    Joined:
    Jul 31, 2012
    Messages:
    10,351
    Likes Received:
    1,160
    Hi Jeff:

    And also, you are indeed splitting CH9 using a Y-cable -- but, as Steve (and your diagram) point out, the powered-off Radian pull-down isn't happening. I'm interested in your thinking about using the main flight battery for the non-flight-critical systems....I can see the obvious advantage of reduce weight, of course.

    Andy
     
  9. Jeff Scholl

    Jeff Scholl Distributor

    Joined:
    Jun 29, 2012
    Messages:
    240
    Likes Received:
    50
    Hello,
    I used to subscribe to the separate power 10-15 years ago, but have since changed my ways trying to simplify.
    What is the "powered off Radian pull down"?
    Cheers,
    Jeff
     
  10. Andy Johnson-Laird

    Andy Johnson-Laird Administrator
    Staff Member

    Joined:
    Jul 31, 2012
    Messages:
    10,351
    Likes Received:
    1,160
    Thanks for the clarification, Jeff.

    Powered Off Radian Pull Down
    If you use a Y-cable to split the SUMO, connecting one side to the FC board, and the other side to a Radian, then if the Radian is not powered on (because it's on a separate LiPo/BEC), the FC fails to detect the GR Rx. That much is fact.

    The theory is that the Radian, when not powered on, will pull down the PPM signal to the point where the FC cannot detect it. JohnC is not sure that this will actually happen so, hence, presently it is just a theory.

    Andy.
     
  11. Jeff Scholl

    Jeff Scholl Distributor

    Joined:
    Jun 29, 2012
    Messages:
    240
    Likes Received:
    50
    Hi Andy,
    I split Ch9 (plain jane PWM) for the Mode On/Off. I forget the side effects when I split the SUMO from Ch8, but it was enough to decide it wasn't going in the air.

    Cheers,
    Jeff
     
  12. Cyril Perrier

    Cyril Perrier New Member

    Joined:
    Jul 27, 2012
    Messages:
    5
    Likes Received:
    0
    Did you try to connect an outpout from your flight control board to your tilt radian ? It's a like a pwm signal...
    For example servo 3 (no compensation from MK board) to input 1 of your tilt radian.
    You just need one servo lead attached from the aircraft to the gimbal but you'll not use the pan axis so it shouldn't twist.
    Then you can plug the servo lead coming from roll radian to tilt radian pin 3 to power it.

    Finally you don't need to connect roll signal in single operator mode because roll radian works well without.
     
  13. Andy Johnson-Laird

    Andy Johnson-Laird Administrator
    Staff Member

    Joined:
    Jul 31, 2012
    Messages:
    10,351
    Likes Received:
    1,160
  14. Cedric Duchateau

    Cedric Duchateau New Member

    Joined:
    Jan 26, 2013
    Messages:
    13
    Likes Received:
    0
    Hi Carsten,

    thank you for sharing your setup.
    Is it possible to have some more informations about it? Which output of the GR16 did you plug into the radian? How did you configure it?...
     
  15. Jonathan Keao

    Jonathan Keao Member

    Joined:
    Mar 22, 2013
    Messages:
    44
    Likes Received:
    0
    Hi Carsten (or if someone else can answer, please do...)

    I'm going to try and follow the diagram on Quadrocopter's support site to use my MX-20 and ONE GR-24 for the MK electronics AND the 2-axis gimbal with Radians. I can't, though, find instructions on how to setup the MX-20.

    The diagram is here: https://www.quadrocopter.com/assets/images/2AxisWiringDiagram.gif

    The MX-20 is already setup with SUM0 to the FC, though I'm not sure if there's any configuration change that I need to do on the MX-20 in order for Ch. 7, Ch. 9, and Ch.10 to output as per the diagram. It would seems that if I'm summing the channels all to Ch. 8, then the other channels wouldn't output anything. Is this logic flawed?

    I also want to use a Quadropower 1200 mAh 11.1v (3s) to power the Radians and downlink. Would having this separate power source to the Radians be a problem.

    Aloha!
    Jon
     
  16. Jonathan Keao

    Jonathan Keao Member

    Joined:
    Mar 22, 2013
    Messages:
    44
    Likes Received:
    0
    Hi Gary,

    Do you have any telemetry communication issues that others have described with your setup below?

    Aloha!
    Jon

    I'm very much a newbie, and I'm still trying to find the 'best-practices' or 'most common' setup for the 2-axis gimbal with Radians.... :(




     
  17. Gary Haynes

    Gary Haynes Administrator
    Staff Member

    Joined:
    Jul 6, 2012
    Messages:
    5,211
    Likes Received:
    460
    Jon the other pins are still active in the the GR24 and can be used for those other outputs.

    Having a separate power source is fine. Just don't run more than 6 volts since more than that will damage the servos. Most of us are running the small Castle BEC that QC sells. Default voltage is 5.1 volts.

    And from my other post no I am not having any telemetry issues, though I would say that the MC-32 is a bit different the instructions should also work for the MX-20.

    Wish I was where you are. Denver area got 15" of snow yesterday with more on the way.
     
  18. Jonathan Keao

    Jonathan Keao Member

    Joined:
    Mar 22, 2013
    Messages:
    44
    Likes Received:
    0
    Thanks for the help, Gary.

    If I were to supply power to the radians from the 16.8v (through a BEC), are there any specific points that I can safely tap into the supply on the PDB?

    Yeah, weather here has been a scorcher. ;)
     
  19. Gary Haynes

    Gary Haynes Administrator
    Staff Member

    Joined:
    Jul 6, 2012
    Messages:
    5,211
    Likes Received:
    460
    Jon if you are flying the CS8 with the MK PDB you can pull power off of any of the +/- pads. I think there are 4 of them on the PDB board.
     
  20. Jonathan Keao

    Jonathan Keao Member

    Joined:
    Mar 22, 2013
    Messages:
    44
    Likes Received:
    0
    Thanks, Gary. I'm still unsure if I should get another receiver or try the single GR-24 method. Hmmmmm....
     

Share This Page