the GPS_STATUS message is a massive waste of bandwidth, but it is the
only message that tells us the number of visible satellites. So only
send it if that information changes.
This makes MAVLink work better at low baud rates
the 128 byte serial transmit buffer was causing significant problems
with queueing of mavlink messages. With 256 bytes we can fit a lot
more messages out in each pass of the code, which makes telemetry more
efficient
As we discussed on the dev call, we now have enough free ram for this
to be worthwhile
when MANUAL_LEVEL is set to 1, we don't do accelerometer levelling at
startup, and instead used the values saved in the EEPROM. This makes
it easier to do levelling on the bench, or once for a series of
flights for the day
this disables the compass in DCM if MAG_ENABLE is changed in
flight. Without this we would use a fixed yaw once the compass is
disabled
This also makes sure we don't pass the compass to DCM till we have
done a read. This ensures we have a good compass fix for the initial
DCM heading
when we are in the final stages of a landing (less than 2 seconds from
landing waypoint, or less than 3m above landing altitude) we switch
the navigation to use a fixed course. The code previously used the
crosstrack_bearing for this, but this can lead to a large nav_roll in
this final stage of the approach, which can put a wing into the
runway. In autotest we were seeing a nav_roll value of -45 degrees as
we crossed the transition point for the landing, which often led to a
crash.
This changes the code to use the current yaw_sensor value instead,
which is much less likely to lead to large rolls in the final landing
stages.
hold_course is either -1 (for disabled) or a course to hold for
takeoff/landing. This makes the code a bit clearer.
It also resets hold_course in all non-auto modes, to ensure it isn't
used
If you include airspeed, throttle or groundspeed changes in a mission
then those should not be saved to EEPROM, as otherwise if you restart
and re-fly the mission you will be starting with different parameters
to the ones you used for the first flight.
This is particularly important for setting the target airspeed when
coming in for a landing. You typically set a low target, but if you
fly again the next day I think it would be a real surprise to find
that your loiter airspeed has then changed to the value from the
landing part of your last mission.
This one can be argued either way, but I think that not saving these
changes is the more conservative choice, and better fits the
'principal of least surprise'
Andrew Tridgell
Michael Oborne
Amilcar Lucas
Adam M Rivera
Pat Hickey
rmackay9
Phil