ArduPilot simpleRTK3B Heading configuration

Ardupilot Septentrio Heading Mosaic

Get high precision GNSS based heading to your ArduPilot project with the simpleRTK3B Heading receiver, based on Septentrio Mosaic-H, with this easy tutorial.

Important things before start:

  • This tutorial is based on the simpleRTK3B Heading, if you have a different hardware you may need to apply some changes in this tutorial.
    We have prepared another tutorial for the simpleRTK2B+heading kit.
  • The configuration of the GNSS receiver will set it at an output rate of 10Hz, with NMEA GGA, RMC and HDT sentences sent to the autopilot.
  • We have validated the tutorial with these autopilots:
    • Holybro Pixhawk4
    • mRo Pixhawk Flight Controller (aka Pixhawk 1)
  • We have validated the tutorial with these firmware versions:
    • ArduRover 4.1.0-dev
    • ArduCopter 4.1.0-dev
    • ArduPlane 4.1.0-dev
  • Do not connect the GNSS receiver with the autopilot yet, we will configure everything independently and connect everything afterwards

Step 1: configure simpleRTK3B Heading

  • Connect the simpleRTK3B Heading to your PC via the POWER+GPS USB C connector
  • Open a browser and type http://192.168.3.1/
  • Go to NMEA/SBC Out > New NMEA stream > Serial port (Next) > COM3 (Next) > Interval (100msec), select GGA, RMC, HDT (Finish)
  • Click Ok
  • On the lower right corner of your browser, this window will appear:
Clik Save button
  • It is important to have both GNSS antennas connected and with a good view of the sky.
  • Go to GNSS > Attitude window
  • Set the Attitude Offset > Heading offset value to match your antenna configuration respect to your platform.
    This means that you should adjust the value until the reported heading value matches the heading of your vehicle (Heading offset will be typically 0, 90, 180 or 270deg, unless you have a rare antenna setup).
  • Click Ok and the click the Save button on the lower right corner window.

Step 2: load ArduPilot configuration file
Since the firmware versions may be different to yours, here is a list of all the parameters modified with respect to the default configuration:

COMPASS_ENABLE,0
COMPASS_USE,0
COMPASS_USE2,0
COMPASS_USE3,0
EK3_MAG_CAL,5
EK3_SRC1_YAW,2
GPS_AUTO_CONFIG,0
GPS_AUTO_SWITCH,0
GPS_RATE_MS, 100
GPS_TYPE,16
SERIAL1_BAUD,115
SERIAL1_PROTOCOL,5

Step 3: reset your autopilot

  • After saving all the parameters make sure you remove the power from your autopilot

Step 4: connect the heading kit to your autopilot

  • Use the JST connector on the simpleRTK3B Heading and connect it to the Telem1 port.
  • Power the autopilot, wait a few seconds and check the AHRS heading value, it should match the direction between your antennas.
  • As an additional check to see if it is working, the heading value of the AHRS should be the same as the one in CTRL+F > MAVlink inspector > GPS_RAW_INT > yaw
  • Notice that the EKF will take into account the gyroscope readings so if you turn the autopilot without turning the whole vehicle frame where the antennas are mounted the heading will change, although after a few seconds it will go back to the GNSS calculated heading.