2 mid-air crashes using v1.8.2

Hi everyone,

I have encountered 2 mid-air crashes on last Thursday & Sunday. In both cases, the log file (at least according to my understanding) ends abruptly.

I couldn’t find any hardfault logs on the sdcard, but I also doubt both cases were battery disconnect or something like that (I can’t rule that out completely, but I’m pretty sure it isn’t the case)

I would appreciate any help on figuring out what happened, or at least what should I do in order to provide more information if those crashes happen again.

  1. Flight log #1 (Thursday): https://review.px4.io/plot_app?log=cacc99f6-5d04-4742-a5f6-f18c79e7c2d0
  2. Flight log #2 (Sunday): https://review.px4.io/plot_app?log=0861c9ed-2f5a-476f-97b8-7f97653b2dc2

Some information on the configuration:

  1. I am running v1.8.2 on Pixhawk4 with a slight modification in mb102xx (just changed the BUS_ID)
  2. I was running using EKF2_HGT_MODE=2, and I increased the LOCAL_POSITION_NED mavlink rate to 200
  3. I doubt those changes are the root cause, but just mentioning them.

I wasn’t able to find anything suspicious in the logs, appreciate your help.


We’re currently investigating an I2C issue in the NuttX OS. Do you have particularly long I2C wires?

I am using 2 I2C devices as far as I understand:

  1. ublox n8m gps + compass - the compass is connected to the GPS port using a ~20cm I2C cable.
  2. mb12xx sonar - connected to the I2C-A port using a ~10cm cable

Is there a way to validate / rule out this assumption? Any particular logs I can add?

Thanks for the help!

Do any of the I2C cables go close to ESCs, switching regulators or power cables? Even with the NuttX issue fixed you could still have data corruption issues.

Not really, they are not bound together…

Any reference to the nuttx I2C issue you were mentioning? Any indications I can look for to be sure this is what I’m hitting?