PITS Raspbian Update

We’ve identified a Pi software issue in Raspbian Stretch, and we strongly recommend that customers update to the latest (Buster) release.

The fault causes RTTY telemetry to stop (just sends carrier) and LoRa and APRS to stop also.

What Makes It Happen?

The triggers for the fault are:

  • Raspbian Stretch (specifically kernel 4.14.344 but others may well be affected)
  • Pi V2 camera (Sony)
  • Taking full-sized images

The fault normally only happens during flight, because with the default configuration PITS only takes full-sized images when above a set GPS altitude (default 2000m).

What Happens?

When the fault occurs, the Pi ACT LED is solidly on and all SD access locks up. Only processes that do not access the SD continue. Since the tracker RTTY, GPS and LoRa threads normally write logs to the SD card, then those lock also hence the lack of telemetry.

Does It Affect Me?

If your tracker does not take images then it is not affected. Or, if it uses a webcam or a GoPro instead of the Sony camera, then it is not affected. In our testing, a Pi V1 camera is also unaffected but if you use one we recommend updating the OS anyway.

We know that current Raspbian (Buster) is fine, so if you’re already using it, then relax.

We don’t know exactly which previous releases are affected. You can test your own installation by running a soak test. First edit pisky.txt, edit the “high=” line and set it to zero or any altitude below your location, thus forcing the camera to take large images. Restart the tracker (e.g. reboot) and leave for a few hours; if you are affected then within 1-2 hours the tracker will stop sending telemetry, stop taking images, and the SD ACT light will be on solidly.

How To Fix?

We recommend following the usual instructions to build a fresh SD image from the latest Buster release.