This is fully backwards compatible: If the throttle trim is set to
the minimum then it's the legacy calibration and gets
interpreted such that there is no trim and behavior remains as before.
If the trim is set to a different value than the minimum then it gets
used like with all other channels which was unsupported before.
Using mixers on the IO side had a remote benefit of being able to
override all control surfaces with a radio remote on a fixed wing.
This ended up not being used that much and since the original design
10 years ago (2011) we have been able to convince ourselves that the
overall system stability is at a level where this marginal benefit,
which is not present on multicopters, is not worth the hazzle.
Co-authored-by: Beat Küng <beat-kueng@gmx.net>
Co-authored-by: Daniel Agar <daniel@agar.ca>
Matthias Grob