No signals to topside

Hi all,

we have been building the BlueROV2 over the last few weeks… and thanks the bluerobotics team for that, it is a great fun!

We did all steps successfully and we have now a pretty much complete system. Just notice we had some final doubts about the topside structure as we initially wired directly the tether to the laptop using a rj45, before to realize that an other fanthom-x should be used instead… indeed we have been wondering before on why we had a spare one (!).

Anyway, it seems now that all is place and we indeed get all “the right” LEDs on. The topside fathom-x board is also powered and the link is green. However we do not get any signals on QGC. We had no problem with QGC during calibration and we used the image file on the SDcard for the raspery-pi. Firmware was also updated on the pixHawk sometime in September and the latest QGC version was also installed at that time.

So we are wondering where the problem could likely be… Further check the connections or we should focus on rasperi-pi and ardusub?

Thanks for any advice on this!



well, we went down the route of checking raspberry-pi and we find out that the SDcard is damaged. We do not know at this point if the raspberry-pi itself is damaged as well. We get the power on and we tried to have other SDcards with the image boot file on. Nothing happen even when we direct the video output to an external screen.

Anyone experienced something similar?


Hi Patrizio,

Thanks for the post. I’m glad you narrowed this down to the SD cards. On rare occasions they can become corrupted during the flashing process. We realized this recently and started testing every single one, but yours may not have been included in that. I would recommend reflashing with the Ardusub-Raspbian image as described here.

If you’re using Windows, the flashing instructions are here: Raspberry Pi Documentation - Getting Started

In either case, make sure you download the most recent ArduSub-Raspbian image file:

Let me know if that helps.


Hi Rusty,

thanks for the reply. Unfortunately I cannot read the original SD card on my mac (I get an error message that the card cannot be read) and we only have 64 Gb available at the moment, which apparently has some issue with the formatting to be used as boot. Hence we decided to buy a new 8 Gb and try again tomorrow. Meanwhile do you know if even in the absence of a SD card, we can get some video output message from the rapspberry-pi? I am concerned that the raspberry is just dead and we need to replace it (although we do get the red power led on).


Hi Patrizio,

Okay. The SD card (and the Linux on it) actually use a file system type that the Mac can’t see. There’s probably not anything wrong with it. You can follow the instruction here to flash it:

There is no video without the SD card, unfortunately. You can plug the Raspberry Pi into an HDMI cable and screen with an SD card to see if it’s booting up at all.


Hi Rusty,

thanks for the advice. We did flash again the SD card and we do indeed see now the raspberry-pi booting.

I have also installed the latest QGC again, but still we do not get the ROV visible from the laptop (a MacBook air).

When the laptop is directly connected to the pixhawk it works fine (all summary, joystick, etc. are there). On the topside the green LED light for the link is on (on the fathom-X) or off when the tether is unplugged (and actually transmission on the ethernet cable increases when the ether is connected). Looking at the activities on the raspberry-pi we do see running at between 15 - 20% of the CPU. So what can it be? Any more suggestions to fix this issue?

Thanks a lot for the assistance on this.




ok we found out… IP address on the laptop. Now we are up and running ready for the next issue!

Thanks again