Copter firmware for px4 hkpilot32 FMUv2?

Which firmware is the correct firmware for px4 hkpilot32 based off FMUv2?

I went to the copter stable px4 firmware. http://firmware.ardupilot.org/Copter/stable/PX4/
Is arducopter-v1, v2, v3, or v4?

Also does the firmware have to match up with the mission planner version?

If I update the firmware will it delete my previous parameters?

Thanks

Check Chris answers to my questions. He has link to newest stable V3.6.7. It is not the one in MP. Ed

THanks, would you happen to have a link?

I don’t know your system behaves, but when I launch MP and click Initial Setup > Install Firmware all three of my Win10 computers (one desktop and two laptops) immediately find AC 3.6.7.

The easiest way to find out exactly which FMU you have is to use qGroundControl to update the bootloader: https://docs.px4.io/en/advanced_config/bootloader_update.html

I did this on 2 2.4.8 Pixhawks. One is an FMU2 and the other is an FMU3.

If you do this it will wipe all of your settings, so make a backup.