Chris, I have been able to use QGC to upload the px4 control stack with no problem, but it can’t upload from MP, and all I have is the .apj file which QGC can’t use. I’ll play around more with this tomorrow…
John, yeah, I’ve got the right com port selected. With the px4 control stack installed on the Pixhawk 4, I am able to connect to the Pixhawk 4 from MP on COM3, but it fails whenever I try to upload firmware to that port.
Does it give you that error with or without the pixhawk 4 connected to your pc?
Good call, John… The result is identical either way. For some reason, Mission Planner is willing to connect to the device as a MAVLink interface through COM3, but not to do a firmware update.
I don’t know what the com port issue is about. I think that’s a Windows issue as linux doesn’t use com ports. Master is broken this morning as tridge has a WIP on updating some stuff for ChibiOS. So I reset HEAD to the build from a couple days ago and ran a build - try the arducopter.bin file (this one is for multirotors) with QGC from this link
https://drive.google.com/open?id=1u9rXAVcZjz99TjtO5y78KMTO_x9lBfRt
The build is in the FMU v5 folder
Thanks, Chris… That seems to have done it. I uploaded the bin file using QGC and it seems ok. Now I have some new learning to do…
I probably read it all wrong, or missed something obvious. 
I’ve been able to successfully install Arducopter on the Pixhawk 4 via Mission Planner, but I’ve ran into an issue: Changes made to any parameters are not being saved, hence all parameters are defaulting upon power cycle. I can make parameter changes, write those changes, verify changes by refreshing the parameter list, but as soon as I power cycle those changes are lost.
Any advice would be much appreciated 
Hello everyone,
I know this topic is dead for nearly 3 months, but I think my question fits here nicely. I hope I will receive some answers
Some fellow students and me are currently developing an airborne windenergy system in university. Therefore we plan to use a modified version of the ArduPlane source code on the new Pixhawk4 with FMU-V5.
I managed to upload a prebuild version of ArduPlane(V3.9.3) with Mission Planner to the pixhawk4. On the first view it seems to work fine.
Now the question: How can I upload an modified version of ArduPlane to my pixhawk4? I can build it with the ./waf command, but the target board I would need, px4-v5, is not available yet. With the target px4-v4 it does not work. Is there a way to add px4-v5 to my list of boards? Or any other way to build modified code and load onto the new pixhawk4?
Thanks in advance for any help,
Happy developing,
Kevin
Target is fmuv5, not px4-v5.
With our build system the “px4-vN” targets are all built on nuttx, and will be deprecated soon, whereas “fmuvN” is on ChibiOS. Pixhawk4 (and many other of the recently added boards) are only supported on ChibiOS.
Great project!