I have a strange issue with Pixhawk 4. This happened the first time when I stalled a servo until it melted . The brownout caused the Pixhawk to power off (fine), however, even after the melted servo stopped smoking and no current was going through it, Pixhawk wouldn’t boot back up itself. After disconnecting and reconnecting the battery, it booted up as usual and everything worked fine.
Why do I care then? - If this had happened in the air, I would have lost the plane. The desired reaction would be that the Pixhawk boots back up when it detects enough power available.
This made me investigate a bit more into what is going on, and I can say that this is not a sole incident. I can reproduce it with about 50% success rate if I short the power board on purpose with a smoke-stopper connected, or if I just short it with a 6A polyfuse directly, you could think about other ways to achieve this. After you remove the shorting, Pixhawk won’t boot up. Instead, very tiny ticking sound is coming out of it, I suppose similar as when you try to power it with something under 5V.
I tested this on two different Pixhawk 4 and PM07 board sets. Firmware PX4 1.9.2. To test if it is not a power distribution board issue, I powered the Pixhawk using a second battery-pdb set to the second power port while the ticking was still going on and then removed the first pdb. Still ticking, no reboot.
My question is, is this a feature or a bug? What can be done? I don’t want a single burned servo to turn off the whole plane mid air. EDIT: (for no longer than necessary)
Can anyone say if this happens with other controllers too, like the Cube or Durandal?