Release 3.1.0, 22 December 2016
===============================
The ArduPilot development team is proud to announce the release of
version 3.1.0 of APM:Rover. This is a major release with a lot of
changes so please read the notes carefully!

A huge thanks to ALL the ArduPilot developers.  The Rover code
benefits tremendously from all the hard work that goes into the Copter
and Plane vehicle code.  Most of the code changes in this
release were not specifically for Rover however because of the
fantastic architecture of the ArduPilot code Rover automatically gets
those enhancements anyway.

Note that the documentation hasn't yet caught up with all the changes
in this release. We are still working on that, but meanwhile if you
see a feature that interests you and it isn't documented yet then
please ask.

The PX4-v2 build has had CANBUS support removed due to firmware size
issues.  If Rover users want CANBUS support you will need to install
the PX4-v3 build located in the firmware folder here:
http://firmware.ap.ardupilot.org/Rover/stable/PX4/

EKF1 has been removed as EKF2 has been the long term default and is
working extremely well and this has allowed room for EKF3.

EKF3 is included in this release but it is not the default.  Should
you want to experiment with it set the following parameters:
AHRS_EKF_TYPE=3
EK3_ENABLE=1
but note it is still experimental and you must fully understand the
implications.

New GUIDED Command
------------------
Rover now accepts a new message MAV_CMD_NAV_SET_YAW_SPEED which has an
angle in centidegrees and a speed scale and the rover will drive based
on these inputs.

The ArduPilot team would like to thank EnRoute for the sponsoring of
this feature
http://enroute.co.jp/

COMMAND_INT and ROI Commands
----------------------------
COMMAND_INT support has been added to Rover.  This has allowed the
implementation of SET_POSITION_TARGET_GLOBAL_INT, 
SET_POSITION_TARGET_LOCAL_NED and DO_SET_ROI as a COMMAND_INT

The ArduPilot team would like to thank EnRoute for the sponsoring of
this feature
http://enroute.co.jp/

Reverse
-------
Its now possible in a mission to tell the rover to drive in
Reverse. If using Mission Planner insert a new Waypoint using "Add
Below" button on the Flight Plan screen and select from the Command
drop down list you will see a new command "DO_SET_REVERSE". It takes 1
parameter - 0 for forward, 1 for reverse. It's that simple. Please give
it a try and report back any success or issues found or any questions
as well.

The ArduPilot team would like to thank the Institute for Intelligent
Systems Research at Deakin University
(http://www.deakin.edu.au/research/iisri16) for the sponsoring of the
reverse functionality.

Loiter
------
This changes brings the LOITER commands in line with other ArduPilot
vehicles so both NAV_LOITER_UNLIM and NAV_LOITER_TIME are supported and are
actively loitering. This means for instance if you have set a boat to
loiter at a particular position and the water current pushes the boat off
that position once the boat has drifted further then the WP_RADIUS
parameter distance setting from the position the motor(s) will be
engaged and the boat will return to the loiter position.

The ArduPilot team would like to thanko MarineTech for sponsoring this
enhancement.
http://www.marinetech.fr

Note: if you currently use Param1 of a NAV_WAYPOINT to loiter at a
waypoint this functionality has not changed and is NOT actively loitering.

Crash Check
-----------
Rover can now detect a crash in most circumstances - thanks Pierre
Kancir. It is enabled by default and will change the vehicle into HOLD
mode if a crash is detected.  FS_CRASH_CHECK is the parameter used to
control what action to take on a crash detection and it supports
0:Disabled, 1:HOLD, 2:HoldAndDisarm

Pixhawk2 heated IMU support
---------------------------
This release adds support for the IMU heater in the Pixhawk2,
allowing for more stable IMU temperatures. The Pixhawk2 is
automatically detected and the heater enabled at boot, with the target
IMU temperature controllable via BRD_IMU_TARGTEMP.
Using an IMU heater should improve IMU stability in environments with
significant temperature changes.

PH2SLIM Support
---------------
This release adds support for the PH2SLIM variant of the Pixhawk2,
which is a Pixhawk2 cube without the isolated sensor top board. This
makes for a very compact autopilot for small aircraft. To enable
PH2SLIM support set the BRD_TYPE parameter to 6 using a GCS connected
on USB.

AP_Module Support
-----------------
This is the first release of ArduPilot with loadable module support
for Linux based boards. The AP_Module system allows for externally
compiled modules to access sensor data from ArduPilot controlled
sensors. The initial AP_Module support is aimed at vendors integrating
high-rate digital image stabilisation using IMU data, but it is
expected this will be expanded to other use cases in future releases.

Major VRBrain Support Update
----------------------------
This release includes a major merge of support for the VRBrain family
of autopilots. Many thanks to the great work by Luke Mike in putting
together this merge!

Much Faster Boot Time
---------------------
Boot times on Pixhawk are now much faster due to a restructuring of
the driver startup code, with slow starting drivers not started unless
they are enabled with the appropriate parameters. The restructuring
also allows for support of a wide variety of board types, including
the PH2SLIM above.

This release includes many other updates right across the flight
stack, including several new features. Some of the changes include:

 - log all rally points on startup
 - the armed state is now logged
 - support added for MAV_CMD_ACCELCAL_VEHICLE_POS
 - support MAVLink based external GPS device
 - support LED_CONTROL MAVLink message
 - support PLAY_TUNE MAVLink message
 - added AP_Button support for remote button input reporting
 - support 16 channel SERVO_OUTPUT_RAW in MAVLink2
 - added MAVLink reporting of logging subsystem health
 - added BRD_SAFETY_MASK to allow for channel movement for selected channels with safety on
 - lots of HAL_Linux improvements to bus and thread handling
 - added IMU heater support on Pixhawk2
 - allow for faster accel bias learning in EKF2
 - added AP_Module support for loadable modules
 - merged support for wide range of VRBrain boards
 - added support for PH2SLIM and PHMINI boards with BRD_TYPE
 - greatly reduced boot time on Pixhawk and similar boards
 - fixed magic check for signing key in MAVLink2
 - fixed averaging of gyros for EKF2 gyro bias estimate
 - added support for ParametersG2
 - support added for the GPS_INPUT mavlink message
 
 

Release 3.0.1, 17 June 2016
===========================
The ArduPilot development team is proud to announce the release of
version 3.0.1 of APM:Rover. This is a minor release with small but
important bug fix changes.

The two main motivations for this release
1. Fixing the arming for skid steering Rovers
2. Fix to the rover steering that should really improve steering of
all rovers.

Skid Steering Arming
--------------------
Fixed arming for Skid Steering rovers. You should now be able to arm
your skid steering rover using the steering stick. NOTE skid steering
Rovers - you will not be able to disarm. The reason for this is zero
throttle full left turn is a perfectly valid move for a skid steering
rover as it can turn on the spot. You don't want to be executing this
and have the rover disarm part way through your turn so we have
disabled disarming via the steering stick. You can still disarm from
the GCS.  Thanks to Pierre Kancir for working on this.

Improved Steering Control
-------------------------
For historical reason's the steering controller was using the raw GPS
data for ground speed without any filtering. If you have every graphed
this data you will see on a rover its very spiky and all over the
place. This spiky'ness was feeding into the lateral accel demand and
causing inaccuracies/jitters. Now we using the EKF GPS filtered data
which is much smoother and accurate and the steering control has
greatly improved.

Improved Cornering
------------------
Previously when corning we didn't take into account any "lean or tilt"
in the rover - we assumed the turns were always flat. We have changed
this to now take into account any lean so turning should be more
accurate. Boat users should really benefit from this too.

MAVLink2 support has been added
-------------------------------
See this post by Tridge -
http://discuss.ardupilot.org/t/mavlink2-is-in-ardupilot-master/9188/1


The other changes in this release are:

 - setting your sonar_trigger_cm to 0 will now log the sonar data but
   not use it for vehicle avoidance.
 - the throttle PID is now being logged
 - range finder input is now being captured (thanks to Allan Matthew)
 - added LOG_DISARMED parameter
 - merge upstream PX4Firmware changes
 - numerous waf build improvements
 - numerous EKF2 improvements


Release 3.0.0, 5 April 2016
===========================
The ArduPilot development team is proud to announce the release of
version 3.0.0 of APM:Rover. This is a major release with a lot of
changes so please read the notes carefully!

A huge thanks to ALL the ArduPilot developers.  The Rover code
benefits tremendously from all the hard work that goes into the Copter
and Plane vehicle code.  Most of the code changes in this
release were not specifically for Rover however because of the
fantastic architecture of the ArduPilot code Rover automatically get's
those enhancements anyway.

Note that the documentation hasn't yet caught up with all the changes
in this release. We are still working on that, but meanwhile if you
see a feature that interests you and it isn't documented yet then
please ask.

The 3.x.x releases and above DON'T support APM1/APM2
----------------------------------------------------
This release DOES NOT SUPPORT the old APM1/APM2 AVR based boards. The
issue is the amount of effort required to keep the new code ported to
the old platforms.  We are very sorry this has to occur and if there
is someone who is willing and technically capable of doing this work
then please let us know.
There will be a discussion created on ArduPilot forums where people
can request features in the new code be backported to the APM code to
run on the AVR boards and if it is reasonably easy and they are
willing to do the beta testing we will do our best to make it happen.

EKF2 - New Kalman Filter
------------------------
Paul Riseborough has been working hard recently on the new
EKF2 variant which fixes many issues seen with the old estimator. The
key improvements are:

  - support for separate filters on each IMU for multi-IMU boards
    (such as the Pixhawk), giving a high degree of redundency
  - much better handling of gyro drift estimation, especially on
    startup
  - much faster recovery from attitude estimation errors

After extensive testing of the new EKF code we decided to make it the
default for this release. You can still use the old EKF if you want to
by setting AHRS_EKF_TYPE to 1, although it is recommended that the new
EKF be used for all vehicles.

In order to use the EKF we need to be a bit more careful about the
setup of the vehicle. That is why we enabled arming and pre-arm checks
by default. Please don't disable the arming checks, they are there for
very good reasons.

UAVCAN new protocol
-------------------
The uavcan change to the new protocol has been a long time coming, and
we'd like to thank Holger for both his great work on this and his
patience given how long it has taken to be in a release. This adds
support for automatic canbus node assignment which makes setup much
easier, and also supports the latest versions of the Zubax canbus GPS.

Support for 4 new Boards
------------------------
The porting of ArduPilot to more boards continues, with support
for 3 new boards in this release. They are:

 - the BHAT board
 - the PXFmini
 - the QualComm Flight
 - the Pixracer

More information about the list of supported boards is available here:
http://dev.ardupilot.org/wiki/supported-autopilot-controller-boards/

Startup on a moving platform
----------------------------
One of the benefits of the new EKF2 estimator is that it allows for
rapid estimation of gyro offset without doing a gyro calibration on
startup. This makes it possible to startup and arm on a moving
platform by setting the INS_GYR_CAL parameter to zero (to disable gyro
calibration on boot). This should be a big help for boats.

Improved Camera Trigger Logging
-------------------------------
This release adds new CAM_FEEDBACK_PIN and CAM_FEEDBACK_POL
parameters. These add support for separate CAM and TRIG log messages,
where TRIG is logged when the camera is triggered and the CAM message
is logged when an external pin indicates the camera has actually
fired. This pin is typically based on the flash hotshoe of a camera
and provides a way to log the exact time of camera triggering more
accurately. Many thanks to Dario Andres and Jaime Machuca for their
work on this feature.

PID Tuning
----------
You can now see the individual contributions of the P, I and D
components for the Steering PID in the logs (PIDY), allowing you to
get a much better picture of the performance.

Vibration Logging
-----------------
This release includes a lot more options for diagnosing vibration
issues. You will notice new VIBRATION messages in MAVLink and VIBE
messages in the dataflash logs. Those give you a good idea of your
(unfiltered) vibration levels. For really detailed analysis you can
setup your LOG_BITMASK to include raw logging, which gives you every
accel and gyro sample on your Pixhawk. You can then do a FFT on the
result and plot the distribution of vibration level with
frequency. That is great for finding the cause of vibration
issues. Note that you need a very fast microSD card for that to work!

More Sensors
------------
This release includes support for a bunch more sensors. It now supports
3 different interfaces for the LightWare range of Lidars (serial, I2C
and analog), and also supports the very nice Septentrio RTK
dual-frequency GPS (the first dual-frequency GPS we have support
for). It also supports the new "blue label" Lidar from Pulsed Light
(both on I2C and PWM).

For the uBlox GPS, we now have a lot more configurability of the
driver, with the ability to set the GNSS mode for different
constellations. Also in the uBlox driver we support logging of the raw
carrier phase and pseudo range data, which allows for post RTK
analysis with raw-capable receivers for really accurate photo
missions.

Better Linux support
--------------------
This release includes a lot of improvements to the Linux based
autopilot boards, including the NavIO+, the PXF and ERLE boards and
the BBBMini and the new RasPilot board.

On-board compass calibrator
---------------------------
We also have a new on-board compass calibrator, which also adds calibration
for soft iron effects, allowing for much more accurate compass
calibration.

Lots of other changes!
----------------------
The above list is just a taste of the changes that have gone into this
release. Thousands of small changes have gone into this release with
dozens of people contributing. Many thanks to everyone who helped!

Other key changes
-----------------
- fixed the MAV_CMD_DO_SET_HOME (thanks salonijain12)
- fixed bug when reverse throttle would increase speed in AUTO
- fixed a bug going into guided and rover still moving
- loitering at a waypoint if Param1 is non-zero
- update uavcan to new protocol
- fixed reporting of armed state with safety switch
- added optional arming check for minimum voltage
- improved text message queueing to ground stations
- re-organisation of HAL_Linux bus API
- improved NMEA parsing in GPS driver
- improved autoconfig of uBlox GPS driver
- support a wider range of Lightware serial Lidars
- improved non-GPS performance of EKF2
- improved compass fusion in EKF2
- improved support for Pixracer board
- improved NavIO2 support
- added BATT_WATT_MAX parameter
- enable messages for MAVLink gimbal support
- use 64 bit timestamps in dataflash logs
- added realtime PID tuning messages and PID logging
- fixed a failure case for the px4 failsafe mixer
- added DSM binding support on Pixhawk
- added vibration level logging
- ignore low voltage failsafe while disarmed
- added delta velocity and delta angle logging
- allow steering disarm based on ARMING_RUDDER parameter
- prevent mode switch changes changing WP tracking
- fixed parameter documentation spelling errors
- send MISSION_ITEM_REACHED messages on waypoint completion
- enable EKF by default on rover
- Improve gyro bias learning rate for plane and rover
- Allow switching primary GPS instance with 1 sat difference
- added NSH over MAVLink support
- added support for mpu9250 on pixhawk and pixhawk2
- Add support for logging ublox RXM-RAWX messages
- lots of updates to improve support for Linux based boards
- added ORGN message in dataflash
- added support for new "blue label" Lidar
- switched to real hdop in uBlox driver
- improved auto-config of uBlox
- raise accel discrepancy arming threshold to 0.75
- improved support for tcp and udp connections on Linux
- switched to delta-velocity and delta-angles in DCM
- improved detection of which accel to use in EKF
- improved auto-detections of flow control on pixhawk UARTs
- added HDOP to uavcan GPS driver
- improved sending of autopilot version
- log zero rangefinder distance when unhealthy
- added PRU firmware files for BeagleBoneBlack port
- fix for recent STORM32 gimbal support
- changed sending of STATUSTEXT severity to use correct values
- added new RSSI library with PWM input support
- fixed MAVLink heading report for UAVCAN GPS
- support LightWare I2C rangefinder on Linux
- improved staging of parameters and formats on startup to dataflash
- added new on-board compass calibrator
- improved RCOutput code for NavIO port
- added support for Septentrio GPS receiver
- support DO_MOUNT_CONTROl via command-long interface
- added CAM_RELAY_ON parameter
- moved SKIP_GYRO_CAL functionality to INS_GYR_CAL
- new waf build system
- new async accel calibrator
- better rangefinder power control
- dataflash over mavlink support
- settable main loop rate
- hideable parameters
- improved logging for dual-GPS setups
- improvements to multiple RTK GPS drivers
- numerous HAL_Linux improvements
- improved logging of CAM messages
- added support for IMU heaters in HAL_Linux
- support for RCInput over UDP in HAL_Linux
- improved EKF startup checks for GPS accuracy
- added raw IMU logging for all platforms
- configurable RGB LED brightness
- improvements to the lsm303d driver for Linux


Release 2.50, 19 June 2015
==========================

The ardupilot development team has released version 2.50 of
APM:Rover.  This release is mostly a backend improvement to ArduPilot
but a few new features and bug fixes are included.

Re-do Accelerometer Calibration
-------------------------------
Due to a change in the maximum accelerometer range on the Pixhawk all
users must re-do their accelerometer calibration for this release.


Only 3D accel calibration
-------------------------
The old "1D" accelerometer calibration method has now been removed, so
you must use the 3D accelerometer calibration method. The old method
was removed because a significant number of users had poor experiences.


Changes in this release are:

        - CLI_ENABLED parameter added so the CLI can now be accessed
          in Rover
        - PID logging for the steering controller.  It its now
          possible to graph what the P, I and D are doing as your
          driving the rover around to enable much better tuning of the
          vehicle.
        - Transition from .pde file to .cpp files for improved
          development.
        - GIT Submodules created for PX4Firmware, PX4Nuttx and uavcan
          git repositories for improved development.
        - Followme mode now works for Rover
        - GUIDED mode significantly improved.  If you have a GCS which is in
          Followme mode if the user then changes mode with the RC transmitter to
          HOLD or anything else then the Rover will STOP listening to the
          Followme updated guided mode waypoints.
        - When going into GUIDED mode the rover went into RTL - this
          is fixed.
        - Added EKF_STATUS_REPORT MAVLink message
        - 64-bit timestamps in dataflash logs
        - Numerous EKF improvements
        - Added support for 4th Mavlink channel
        - Added support for raw IMU logging
        - updated Piksi RTK GPS driver
        - improved support for GPS data injection (for Piksi RTK GPS)
        - The SITL software in the loop simulation system has been completely
          rewritten for this release. A major change is to make it possible to
          run SITL on native windows without needing a Linux virtual
          machine. (thanks Tridge)



Release 2.49, March 4th 2015
----------------------------

The ardupilot development team has released version 2.49 of
APM:Rover.  This release is a bug fix release with two important bugs
found by Marco Walther - Thanks Marco!

The bug fixes in this release are:

    - fixed a sonar problem where objects to the left wouldn't be
      identified - thanks Marco Walther!
    - Fixed the ordering of the AP_Notify call so the main indicator
      light would be correct on startup - thanks Marco Walther!



Release 2.48, February 20th 2015
--------------------------------

The ardupilot development team has released version 2.48 of
APM:Rover.  This release is a bug fix release with some important bugs
found by the users of ardupilot.

The changes in this release are:

  - fixed a bug that could cause short term loss of RC control with
    some receiver systems and configurations
  - allowed for shorter sync pulse widths for PPM-SUM receivers on
    APM1 and APM2
  - fix an issue where battery reporting could be intermittent (thanks
    Georgii Staroselskii!)
  - fixed a mission handling bug that could cause a crash if jump
    commands form an infinite loop (thanks to Dellarb for reporting
    this bug)
  - improved support for in-kernel SPI handling on Linux (thanks to John Williams)
  - support UAVCAN based ESCs and GPS modules on Pixhawk (thanks to
    Pavel, Holger and and PX4 dev team)
  - Multiple updates for the NavIO+ cape on RaspberryPi (thanks to
    Emlid)
  - Lots of EKF changes
  - added support for MAVLink packet routing
  - added detection and recovery from faulty gyro and accel sensors
  - added support for BBBMini Linux port
  - increased number of AVR input channels from 8 to 11
  - auto-set system clock based on GPS in Linux ports
  - added SBUS FrSky telemetry support (thanks to Mathias)
  - Added AK8963 MAG support (thanks Staroselskii Georgii)
  - Added support for second battery
  - Auto formatting of SDCard if it cannot be accessed on startup
  - A number of significant performance improvements for the PX4 platform

The most important bug fix is the one for short term loss of RC
control. This is a very long standing bug which didn't have a
noticeable impact for most people, but could cause loss of RC control
for around 1 or 2 seconds for some people in certain circumstances.

The bug was in the the AP_HAL RCInput API. Each HAL backend has a flag
that says whether there is a new RC input frame available. That flag
was cleared by the read() method (typically hal.rcin->read()). Callers
would check for new input by checking the boolean
hal.rcin->new_input() function.

The problem was that read() was called from multiple places. Normally
this is fine as reads from other than the main radio input loop happen
before the other reads, but if the timing of the new radio frame
exactly matched the loop frequency then a read from another place
could clear the new_input flag and we would not see the new RC input
frame. If that happened enough times we would go into a short term RC
failsafe and ignore RC inputs, even in manual mode.

The fix was very simple - it is the new_input() function itself that
should clear the flag, not read(). 

Many thanks to MarkM for helping us track down this bug by providing
us with sufficient detail on how to reproduce it. In Marks case his
OpenLRSng configuration happened to produce exactly the worst case
timing needed to reproduce the issue. Once Tridge copied his OpenLRS
settings to his TX/RX he was able to reproduce the problem and it was
easy to find and fix.

A number of users have reported occasional glitches in manual control
where servos pause for short periods in past releases. It is likely
that some of those issues were caused by this bug. The dev team would
like to apologise for taking so long to track down this bug!

The other main change was also related to RC input. Some receivers use
a PPM-SUM sync pulse width shorter than what the APM1/APM2 code was
setup to handle. The OpenLRSng default sync pulse width is 3000
microseconds, but the APM1/APM2 code was written for a mininum sync
pulse width of 4000 microseconds. For this release we have changed the
APM1/APM2 driver to accept a sync pulse width down to 2700
microseconds.

Auto format of SD Card
======================
From time to time the SD cards in the PX4 autopilots get corrupted.
This isn't a surprise considering what we do to them.  Your all
familiar with the windows "please unmount or eject your SDCard before
removing" process.  Well we don't do that.  In fact normal operation
is to just pull the power on the SDCard - whilst its being written
too!!  Not to metion the horrible vibration rich environment the
SDCard exists in.  If the autopilot is setup in the internal innards
of your plane/copter/rover this can be a nightmare to get to.  To
resolve that problem Tridge has added code at startup so when
ArduPilot tries to mount to SDCard to access it - if that fails it
will then try to format the SDCard and if successful mount the card
and proceed.  If the format fails then you will get the usual SOS
Audio that makes most of us want to find the buzzer and rip its heart
out.

I mention this in case anyone has precious logs saved on the SDCard or
they are using the SDCard out of their phone with their wedding
photo's on it.  Probably best not to do that and assume any data on
the SDCard can be deleted.

We are also looking to add a parameter to control whether the card is
auto formatted on startup or not but it isn't in there yet.



Release 2.47, November 15th 2014
--------------------------------

The ardupilot development team is proud to announce the release of 
version 2.47 of APM:Rover. This is a minor bug fix release.  The most 
important change in this release is the fixing of the skid steering 
support but there have been a number of fixes in other areas as well.

Full changes list for this release:

  - add support for controlling safety switch on Pixhawk from ground station

  - prevent reports of failed AHRS during initialisation

  - fixed skid steering that was broken in the last release

  - report gyro unhealthy if gyro calibration failed

  - fixed dual sonar support in CLI sonar test

  - fixed Nuttx crash on Pixhawk with bad I2C cables

  - added GPS_SBAS_MODE parameter - turns on/off satellite based augemtation system for GPS

  - added GPS_MIN_ELEV parameter - specifiy the elevation mask for GPS satellites

  - added RELAY_DEFAULT parameter to control default of relay on startup

  - fixed bug in FRAM storage on Pixhawk that could cause parameters changes not to be saved

  - better handling of compass errors in the EKF (Extended Kalman Filter)

  - improved support for linux based autopilots

  - added support for PulsedLight LIDAR as a range finder

Many thanks to everyone who contributed to this release, especially
Tom Coyle and Linus Penzlien for their excellent testing and feedback.

Happy driving!



Release 2.46, August 26th 2014
------------------------------

The ardupilot development team is proud to announce the release of
version 2.46 of APM:Rover. This is a major release with a lot of new
features and bug fixes.

This release is based on a lot of development and testing that
happened prior to the AVC competition where APM based vehicles
performed very well.

Full changes list for this release:

  - added support for higher baudrates on telemetry ports, to make it
    easier to use high rate telemetry to companion boards. Rates of up
    to 1.5MBit are now supported to companion boards.

  - new Rangefinder code with support for a wider range of rangefinder
    types including a range of Lidars (thanks to Allyson Kreft)

  - added logging of power status on Pixhawk

  - added PIVOT_TURN_ANGLE parameter for pivot based turns on skid
    steering rovers

  - lots of improvements to the EKF support for Rover, thanks to Paul
    Riseborough and testing from Tom Coyle. Using the EKF can greatly
    improve navigation accuracy for fast rovers. Enable with
    AHRS_EKF_USE=1. 

  - improved support for dual GPS on Pixhawk. Using a 2nd GPS can
    greatly improve performance when in an area with an obstructed
    view of the sky

  - support for up to 14 RC channels on Pihxawk

  - added BRAKING_PERCENT and BRAKING_SPEEDERR parameters for better
    breaking support when cornering

  - added support for FrSky telemetry via SERIAL2_PROTOCOL parameter
    (thanks to Matthias Badaire)

  - added support for Linux based autopilots, initially with the PXF
    BeagleBoneBlack cape and the Erle robotics board. Support for more
    boards is expected in future releases. Thanks to Victor, Sid and
    Anuj for their great work on the Linux port. 

  - added StorageManager library, which expands available FRAM storage
    on Pixhawk to 16 kByte. This allows for 724 waypoints, 50 rally
    points and 84 fence points on Pixhawk.

  - improved reporting of magnetometer and barometer errors to the GCS

  - fixed a bug in automatic flow control detection for serial ports
    in Pixhawk

  - fixed use of FMU servo pins as digital inputs on Pixhawk

  - imported latest updates for VRBrain boards (thanks to Emile
    Castelnuovo and Luca Micheletti)

  - updates to the Piksi GPS support (thanks to Niels Joubert)

  - improved gyro estimate in DCM (thanks to Jon Challinger)

  - improved position projection in DCM in wind (thanks to Przemek
    Lekston)

  - several updates to AP_NavEKF for more robust handling of errors
    (thanks to Paul Riseborough)

  - lots of small code cleanups thanks to Daniel Frenzel

  - initial support for NavIO board from Mikhail Avkhimenia

  - fixed logging of RCOU for up to 12 channels (thanks to Emile
    Castelnuovo)

  - code cleanups from Silvia Nunezrivero

  - improved parameter download speed on radio links with no flow
    control

Many thanks to everyone who contributed to this release, especially
Tom Coyle and Linus Penzlien for their excellent testing and feedback.

Happy driving!
