Following up on restoring saved params after a firmware update because someone asked this question elsewhere.
"Para to SD" doesn't work for me. Nor does loading a .param file with anything except the IMU_* values. Not sure why. It works for Christof, so maybe it works for others as well. I haven't dug through the code to determine what exactly is going on with "para to sd" (not even sure if this is a QGC feature or if it is supposed to trigger configWriteFile() in config.c).
I came up with the following procedure... From QGC I use the Save File button (in the All/Onboard Parameters windows), which saves the current params to a text file. I then open that file in a plain text editor and edit it so it is just the parameter name and value, one per line (a quick search/replace does the trick). I also change the CONFIG_VERSION to something like 105 (needs to be higher than the current CONFIG_VERSION in the AQ ROM). I then save this as PARAMS.TXT onto my SD card. Then I can insert the card into the AQ and load the params from there.
As Menno described above, if you boot the AQ with the SD card inserted and a PARAMS.TXT file on there, then it will automatically load the params -- but only if the CONFIG_VERSION in the PARAMS.TXT is higher than the version currently in AQ ROM. I do this when flashing new FW version, so when AQ reboots it automatically loads my settings (I then have to reboot again for the radio settings to take effect).
There might be an easier method but I haven't found it yet. We actually need to put this in the docs, I'm just not sure what the best procedure is at the moment (one that works for consistently and for everyone). I realize that people who compile their own firmware often just change the values in config_default, but I don't like doing that for various reasons.
-Max