Copter-3.5 starts beta testing

Copter-3.5-rc1 is now available through the Ground Stations’s (i.e. Mission Planner’s) “Beta firmware’s” link.

The list of changes are copied below, in the Release Notes and in the Copter-3.5 category posting.

This is the first release candidate so please be careful when testing and report any issues in the Copter-3.5 support forum. I’ve created a preliminary Testing To-Do List so we can track what’s been tested.

Warning #1: the FRAME_CLASS parameter must be set depending upon your frame type (1:Quad, 2:Hexa, 3:Octa, 4:OctaQuad, 5:Y6, 7:Tri)

Warning #2: The EKF/GPS failsafe is much less sensitive than AC3.4 which means that if flying in Loiter, PosHold, Guided, Auto, RTL and the compass goes bad, the vehicle will not automatically switching to LAND mode but instead the vehicle will flying erractically. This will be fixed in -rc2.

Copter 3.5-rc1 28-Jan-2017
Changes from 3.4.4

  1. Multicopter firmware consolidated into single binary, users must set FRAME_CLASS parameter (1:Quad, 2:Hexa, 3:Octa, 4:OctaQuad, 5:Y6, 7:Tri)

  2. PixRacer specific items:

  • board LEDs supported
  • ESC calibration start problem resolved (was sometimes not detecting high throttle from pilot)
  1. Relaxed compass calibration and compass consistency checks

  2. Sensor and Optional Hardware Improvements:

  • IMU sampling rate for MPU9250, ICM20608 IMUs to 8kHz for improved vibration resistance (Pixracer, Pixhawk2)
  • Onboard Display (
  • Here+ RTK GPS (UBlox M8P RTK) support
  • LightWare I2C drivers usable on Copter (thanks to in-tree drivers below)
  • MaxBotix sonar with serial interface now supported
  • Bebop optical flow (but sonar not yet operational making this feature currently impossible to use)
  1. Precision Loiter using IRLock sensor (set CH7_OPT to 39)

  2. Delivery improvements:

  1. Pozyx support for Non-GPS flight (

  2. EKF improvements:

  • adjust for user defined sensor offset from IMU
  • improved blending of optical flow and GPS
  • EKF3 added in ride-along. Enable by setting EK3_ENABLE=1
  • improvements when using range finder as primary height reference
  1. Object Avoidance improvements (
  • uses mini-fence
  • accepts MAVLink distance-sensor messages
  • simple avoidance in AltHold mode
  1. Other improvements:
  1. Technical improvements (users may not see a functional change):
  • in-tree drivers lead to improved sharing of drivers with Linux boards
  • copter arming checks consolidated with other vehicles
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