Copter-3.5.4 has been released as the official version for multicopters and traditional helicopters. You should be able to download it through the Mission Planner (and other ground stations) from the Install Firmware screen.
The changes vs Copter-3.5.3 are in the ReleaseNotes.txt and also copied below:
- Compass improvements:
- support added for QMC5883L, LIS3MDL, IST8310
- COMPASS_TYPEMASK parameter allows enabling/disabling individual compass drivers
- LightWare and MaxBotix range finders supported on both I2C buses
- Serial port 5 can be used for telemetry or sensors (previously was only for NuttX console)
- px4pro flight controller supported
- TradHeli fixes:
- motor runup check applies to all flight modes (previously only loiter, poshold, althold)
- swashplate behaviour changes when on ground in acro, stabilize and althold
- servo test function fixed
- direct drive fixed pitch tail fix
- Z-axis Accel P gain default lowered to 0.3
- EKF origin set using SET_GPS_GLOBAL_ORIGIN mavlink message instead of SET_HOME_POSITION
- Intel Aero supports 921600 baud rate between main flight controller and companion computer
- Bug fix to I2C race condition on Pixhawk that could occasionally cause I2C device to not be detected
Perhaps the most important change is the first one mentioned above, the additional compass driver. The popular Honeywell compass (HMC) has become nearly impossible to find so manufacturers of the Pixhawks are moving to other brands of compasses.
Thanks to our beta testers for their help getting this release out!