Appendix B:
MAVLink support of MyFlyDream Crossbow AAT
Crossbow AAT
supports MAVLink V1.1 protocol.
The system requires at least these 2 MAVLink Messages with a 2Hz or higher update rate.
MESSAGE NAME
MESSAGE ID
MAVLINK_MSG_ID_GLOBAL_POSITION_INT
MessageID 33
MAVLINK_MSG_ID_GPS_RAW_INT
MessageID 24
When
you
set
menu
[Protocol->ALT=BARO],
the
Crossbow
AAT
uses
[
MAVLINK_MSG_ID_GLOBAL_POSITION_INT.relative_alt
] field for pitch tracking.
When you set menu [Protoco->ALT=GPS], the Crossbow AAT uses
[
MAVLINK_MSG_ID_GPS_RAW_INT.alt
] for pitch tracking.
Which specific ALT setting you need to use depends on the behaviour of your AutoPilot.
Due to the imperfect world of MAVLink you need to pay more attention about the Altitude
information of MAVLink. There are about 6~7 places allow the autopilots to send altitude data or
barometer data. It's difficult to tell which altitude is exact you need. There are altitudes based on
GPS (ASL), based on a baro-altimeter, or based on a combination result of
GPS+Baro+Accelerometer... etc. Different AutoPilots use these altitude fields in the way they
understand. That's why we offer this [Protocol.ALT] menu to allow users to choose a altitude field
to match their AutoPilot.
Appendix C:
How to update Firmware for the Crossbow