Sentinel drone randomly reboots

  • Hello,

    We recently purchased a Sentinel drone with a microhard modem (set to use 30 dbm, max 1 watt) and wanted to explore the possibility of extending the tracking camera's MIPI cable length. We initially attached a 14.5 cm MIPI extension cable to the tracking camera. and were able to fly for ~10 minutes without GPS in position mode with QVIO. However, ever since then, the drone reboots itself intermittently. On occasion it is stuck in a cycle of rebooting every ~20 seconds.

    Reflashing the drone to the latest version, using a smaller MIPI extension cable (6 cm instead of 14.5), and completely removing the extension cable have been unsuccessful from stopping the drone from rebooting itself. Removing the extension cable seemed to remove the problem for a day, but the drone returned to its state of rebooting itself. Something we noticed is that removing the microhard modem seemed to help the drone stay in a stable state, but this was not consistent.

    Is there anything else we can try to prevent this problem from happening?

  • Dev Team

    Hi @Daniel-Ryu ,
    I apologize for your difficulties, and also I do not know what config everyone has, so I'll try my best to explain one thing I am aware of that can cause your issues, however, I am not certain if it applies to you.
    We know for a fact that our original M0048 boards sold that when plugged into a Voxl2 system can make contact with the J5 120-pin High-Speed B2B connector on Voxl2, triggering a reset.
    When we sell these two boards together, we place Kapton tape over J5 on Voxl2 to mitigate this contact, or if we have these in a configuration together, like on a flight deck, we give it the same treatment and make certain the 5mm spacers used do not let the boards touch.
    However, if someone has purchased a Voxl2 and a Microhard board separately, and then they later pair them up, the issue can easily arise from vibration, insecure mounting, or incorrect spacers applied where bottom components on the M0048 board contact the J5 pins, triggering a reset.
    If you have made some adjustments to your system by using various flex cables, there is a chance you can easily offset the mounting angle of the M0048 board and during flights, it can randomly make contact with J5.
    I would check this out on your drone platform, and try to ensure 5mm spacers are mounted in between the boards. Also, if you have some kapton tape, try placing a good size strip of it over J5 ensuring all the pins are covered.

    It will not harm the Voxl2 at all, and it is easily removed should you wish to try other plug-in boards that utilize J5.

    Hope this helps narrow down your issues.
    Keep us posted, thanks!

  • @Vinny Will look into it, thanks!

  • @Vinny Just wanted to update you guys on this post.

    We tried using the kapton tape on the VOXL2 and making sure there is enough space between the Microhard board and the J5. It hasn't fixed the issue. Any other ideas on how to fix this? We might have to bring the drone into your office for check up.

  • Dev Team

    @rohitpillai Hey Rohit,
    Bummer that wasn't your root cause.
    I've thrown this internally to some other folks for ideas...
    Please bear with us as we figure out the next steps.

  • @Vinny sounds good. Eager for more ideas on how to fix the issue.

  • Dev Team

    @rohitpillai One thing to take a look at is the APM (power module), ensure that the cable and none of it's wires in the connectors of the MCBL-0001 ( have come loose. It may also be worth replacing it as a test.

  • Dev Team

    @rohitpillai Good morning,
    @Vinny filled me in on your issue and I wanted to check in with you on the status. You mentioned coming by the office and so I also wanted to discuss that option with you. Ease let me know if you're still interested in doing that.


  • @tom Yep let me test this out and get back to you.

    @Jeremy-Schmidt If no other solutions work, I will bring it into the office early next week!

  • Dev Team

    @rohitpillai When you removed the extension cable, were you still plugging the tracking camera into the M0054 board directly?

  • Yes, I believe so. We plugged it back in exactly how it was when we picked the drone up.

  • Dev Team

    @rohitpillai do you have a spare mcbl-0001 you can try on this setup?

  • I re-flashed the drone with the new VOXL2 package and it seems to have fixed itself for the time being. I will post in this thread again if the issue springs back up.

  • Update: We are hitting a roadblock where adb shell is not working and the device is not showing up under adb devices. Could you help us here? We are able to SSH in fine but can't use the cable.


  • Dev Team

    @rohitpillai What is the output of lsusb on the host PC with the Sentinel plugged into it via. USB-C?

  • @tom
    This is the lsusb result.
    After rebooting many times, it was detected by lsusb. But when we attach the 'VOXL Microhard Modem Add-on with USB Hub', it kept rebooting and didn't work. I think we have to bring them to your office and check it.

  • Dev Team

    @dlee Any sort of reboot loop is likely to be an MCBL-0001 failure

  • @tom
    VOXL Sentinel
    This is the reboot loop.

  • Dev Team

    @dlee Yep that looks exactly like what I've seen when the MCBL-0001 from the power module goes bad. Do you have another you could try with? If not, you could try making sure all of it's wires are seated fully into their connectors. Depending on how often / how the cable was unplugged the wires may not be fully seated.

  • @tom Yep, I have another. What should I do. Check the power cable?

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