If you are compiling the ardupilot code then the IO code will automatically be built and stored in ROM FS. it will automatically loaded to the IO Board at power up
and was wondering if it needed to be loaded. I see there is 2 files for the px4io now I remember there used to be only one I would put on the sd card then hold the arming button when powering to load it on the px4.
so if I understand correctly, I would just need to download a file, for example “ArduCopter-v2.px4” from here
Ok, I found the answer, right under my nose (either that or it has just been updated in the wiki) i see it is that after 3.1.0 that both files load from one. I see on the px4 you still have to hold the button while powering but do not have to load the file on the SD chip first.
I am not exactly sure, but it looks like on the pixhawk it is not necessary to hold the arm button while powering at any point?