3D Robotics

3689601960?profile=originalCongratulations to Leonard Hall, whose incredibly fast ArduCopter (shown above) won the Sparkfun AVC copter category, and Philip Rowse, whose ArduPlane did the same in fixed wing. In rovers, my own ArduRover came in first in the micro rover category, and there were Pixhawks and APMs throughout all the other categories and contestants. A fantastic day! 

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  • Developer
    It is true, but you should not do it. Unless it stated that the USB is able to supply more than 500mA, then you should assume it can't.

    In reality, it may work, but please don't do it.
  • Is this documented anywhere?  USB2 is only rated for guaranteed 500mah but can often take more depending on the specific implementation.  It clearly states in the link above that the pixhawk is triple power redundant using USB:

    "Pixhawk can be triple-redundant on the power supply if three power sources are supplied. The three rails are: Power module input, servo rail input, USB input."

    Same thing is said on the wiki:


    If this isn't true, then it should be corrected and clearly stated as the current documentation is therefore incorrect.

  • Developer
    Power via the pm, and use servo rail as backup with Zener diode. Keep servo rail voltage at 5.1-5.3v nom
  • Developer
    It can pick automatically between the three sources, but that does not translate to triple redundant.

    Step 1. Powers via Power module.....
    Step 2. Power via servo rail if all voltage (including spikes) remain under 5.7v
    Step 3, if servo power stays above 5.7v, the I/O chip will stay alive, but FMU will die..

    Powering on the bench.... USB is last option for power, max 500ma, this is not enough for reliable flight operation with telemetry and GPS running......
  • @Philip - Oh!  The docs for the pixhawk say that it is triple power redundant and as there are various warnings about powering through the servo rail, I thought this was the easiest and cheapest option for redundancy.


    The usb power pack I'm using has 1A and 2A usb ports so I connected the pixhawk to the 2A port.  Can the pixhawk not draw enough power to operate as backup, or is it bad for it?  It looks like it goes through a 3.3v regulator on the FMU, can that not cope to power the pixhawk and attached receiver?

  • Developer
    @DOM, please do not use the USB in this way, it will give you unpredictable results, the presence of the USB is taken by the system as if you are in a testing mode, power is also limited via this input, so it may not function as expected.

    Basically, don't do this........
    Phil :)
  • I see Leonard was using Ntm motors, 28xx... Does anyone know which version he was using?
  • Aso worth noting that the Pixhawk can actually take a third supply from USB as well.  I do this from a cheap light Lion battery pack from amazon which can supply 2A through USB, and it doesn't suffer from the over-voltage issues that the rail has.

  • http://www.wired.co.uk/news/archive/2014-06/23/balloon-hunting-drone

     I love the comment that points out that it's a good thing there were no bald people present with sunburn ;)

  • That's what Sparkfun wanted.  The NASCAR of robotics.  They're probably sad they didn't get video of my heli going in the lake on Friday night. Pretty good splash, and one terrified stork. ;)

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