Is there a known issue with HERE 3 CAN on ardupilot?


I’m wondering if there is a known issue with CAN on ardupilot?
Or somebody that can help figuring out why we lost our GPS midflight?

We are using the Cube Orange + HERE3 (CAN) and have a fleet of these configured.
They fly very good (using RTK). Though we just had an issue mid-flight.
Mid-flight we suddenly loose our GPS, but our compass keeps working.

We think it cannot be the connection since:

  • compass keeps working

We think it cannot be GPS that broke, since:

  • Repowering the drone gives us back our GPS

We don’t think that CANbus restarted (error or power?)

  • Since the compass kept working and goes over the same data bus

Is it possible that the GPS restarted for some reason and didn’t initialize or something?
Still seems very strange. Any other thoughts what it could be ?

This is very scary, since we have 100+ drones in the air at the same time. We don’t want to loose GPS on those drones. Our older drones use RX/TX instead of CAN and we haven’t had such issues yet. Could this be related?

what firmware version is on the ublox module?

gps version

How are you providing power to the CAN bus?

VCC from the cube is connected to the CAN GPS. (4.69v - 4.74v)

We did the test to find the issue.

So we pulled the RESET pin of the UBLOX chip to GND. As a result resetting the UBLOX GPS.

We loose the GPS for max. 2 seconds after which it starts working again. And amazingly already with fix and very good accuracy.

Using CAN:
We loose the GPS signal and it never recovers. We have to powerdown/reset the full here+ gps, before we get connection again.

So that means that for any reason if the GPS resets on CAN we don’t recover. Which is quite bad. It doesn’t happen a lot (3 times in over 10000 minutes accumulated flight time, but it is very bad in our case.)

I would take steps to improve the Vcc, get it up around 5.1 volts. That low Vcc might be the source of the unrecoverable reset.

the cube power brick is normally around 5.2v. the voltage you have indicated does concern me a little, i would improve that.