Voxl2 reboot due to what it seems a power limitation

Alex Kushleyev

@Riccardo-Franceschini , what device are you using to measure voltage and current?

I would recommend a few simple things to try next:

if you have another power module v3, just swap it out and test again
try swapping the 4-wire power cable that connects the power module and voxl2. Perhaps there is poor contact on the power pins

If the issue still persists, we can try to diagnose it by logging the current draw from battery and also 5V output (power module v3 has current sensing of both)

Vinny

@Alex-Kushleyev @Riccardo-Franceschini
This is most certainly not a power network or power module limitation.
We have extensively stressed the power module for it's 6A rating many many times, including over the full industrial temp range. Every unit also undergoes a "DUT Test" of 3A load during manufacturing testing.
The power module can certainly deliver a full 30W of Continuous power. 1A will barely make it sweat.

The more likely culprits can be either the power cable, which often get stressed easily by pulling on the cables during extraction/removal instead of the cable shroud. This will over time shred the cable junction at the pin contacts. We have a standing rule at HQ to replace the main power cable every few months.
Or, it might be some GPU linked trigger due to a 100% load, especially if you are not seeing any CPU issues.

If you wish to share a photo of your setup, we can help further.
Thanks!

Riccardo Franceschini

Hi,

after experimenting, we found that the problem was a RealSense external camera that we plugged in.

It was connected through USB via the 5G module. Probably, this was causing a short circuit or overload of the board. Anyway, modifying the connection cable so that only the data goes through the board while it is powered separately seems to solve the problem.

Alex Kushleyev

Great to hear you got it figured out!

Vinny

Hi @Riccardo-Franceschini
Our USB hubs have a smart power switch with a message feature that relays back to the host if there is an error/over-current condition on VBUS.
It might be that is what was causing the reset.
But yeah, glad you figured it out!!
Nice work!

Vinny

@Riccardo-Franceschini For future note, this page here lists all the VBUS capabilities in our designs so you know which port (if any) can support your high current use cases:
https://docs.modalai.com/expansion-design-guide/#usb-expansion-over-j3--j5

voxltester

@Vinny

I have the rebooting issue with a VOXL2 flight deck with Microhard radio.

I have tested with 5G board (M0090-3-01) as well. I connected a USB3 ethernet adapter on the 5G board to communicate with my laptop through ethernet cable. The same issue happened.

When I directly powered the system by using a power supply (5V) without a power module, it did not show any rebooting issue....
I am still figuring out, so please let me know what I need to try...

Vinny

Hi @voxltester
Please take a look at this old thread: https://forum.modalai.com/topic/1356/sentinel-drone-randomly-reboots?_=1673383475709

Let us know if that issue with J5 is what is happening.

It is unlikely you are pulling too much current in normal operations as you more than likely have a fault if you think the 5V is drooping.

Thanks!
Vinny

voxltester

@Vinny

I will have a look.

This is very randomly happening...
I changed power source (battery, wall power), but it is working well now...

Is there any way to check GPU usage on VOXL2?

Eric Katzfey

@voxltester voxl-inspect-cpu will show you GPU utilization and temperature

voxltester

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voxltester

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voxltester

@Eric-Katzfey @Vinny @tom
This is totally the power cable problem...
Is there any future plan to make it stable?
It is horrible to imagine the drone crashing due to a reboot issue caused by the power cable.....

Vinny

Hi @voxltester
Apologies you are having issues with the power cable.
We have expressed in several forum posts that care must be employed when removing and inserting any power cables to not tug on the cables themselves, but rather the large shroud/connector housing.
Pulling on any cable repeatedly will dramatically reduce it's service life as it results in frayed conductors at the pin crimp contacts. This is not an MCBL-00001 issue, but all cables in all electronics not just from ModalAI.
There are no plans to change this solution as it has been tried and true for over a decade. Some of my power cables are nearing 13 years old and every one can last that long if handled properly.
If needed, I can try to search through some forum posts where I think we have a picture showing the recommended methods of grabbing onto the plastic shroud instead of the cable conductors themselves. Our team is trained on this method as well.
Hope this helps.