common-external-ahrs: add Xsens External AHRS documentation

common/source/docs/common-external-ahrs-xsens.rst

@@ -0,0 +1,130 @@
+.. _common-external-ahrs-xsens:
+
+===================
+Xsens External AHRS
+===================
+
+`Xsens <https://www.movella.com/products/sensor-modules>`__ (Movella) MTi-series
+IMU / AHRS / GNSS-INS modules can be used as an External AHRS in ArduPilot. The
+Xsens module runs its own onboard sensor fusion and provides attitude, position,
+and velocity to ArduPilot, replacing the internally generated INS/AHRS
+subsystems.
+
+Supported Devices
+=================
+
+The driver communicates with the Xsens module using the Xbus protocol and
+supports the following GNSS/INS-capable products:
+
+=============  ====================  ============  ===============  ================
+Device         Type                  GNSS          Interface        Series
+=============  ====================  ============  ===============  ================
+MTi-7          AHRS / GNSS-INS       External      UART / SPI       MTi 1-series
+MTi-8          AHRS / RTK GNSS-INS   External RTK  UART / SPI       MTi 1-series
+MTi-670(G)     GNSS/INS              Internal      UART (RS232)     MTi 600-series
+MTi-680(G)     RTK GNSS/INS          Internal RTK  UART (RS232)     MTi 600-series
+MTi-G-710      GNSS/INS              Internal      UART             MTi 100-series
+=============  ====================  ============  ===============  ================
+
+The MTi 1-series modules (MTi-7 / MTi-8) support both UART and SPI interfaces.
+
+Connecting the Sensor
+=====================
+
+.. note::
+
+   The MTi 1-series modules (MTi-7 / MTi-8) require a **3.3V** supply. A 5V
+   supply will power the LED but the data link will not work. Power is
+   independent from the data interface; selecting UART or SPI does not change
+   how the module is powered.
+
+UART
+----
+
+Connect the module to a serial port on the autopilot:
+
+=================  ===  =============
+Autopilot          ->   Xsens module
+=================  ===  =============
+TX                 ->   RX
+RX                 ->   TX
+GND                ->   GND
+=================  ===  =============
+
+On the MTi 1-series, set the interface-select pins for UART:
+``PSEL0 = GND``, ``PSEL1 = GND``.
+
+The MTi 600-series (MTi-670/680) and MTi-G-710 use RS232 signal levels by
+default and require an RS232-to-3.3V-TTL level converter between the module and
+the autopilot serial port.
+
+SPI (MTi 1-series)
+------------------
+
+Set the interface-select pins for SPI: ``PSEL0 = GND``, ``PSEL1 = float``.
+
+=================  =============
+Signal             Xsens module
+=================  =============
+NCS (chip select)  SPI CS
+SCLK               SPI clock
+MOSI               data in
+MISO               data out
+GND                GND
+=================  =============
+
+Ensure the module, its power supply, and the autopilot share a common ground.
+
+.. note::
+
+   The Data Ready (DRDY) line is optional. When the board definition does not
+   provide a DRDY GPIO, the driver operates in polling mode.
+
+Configuration
+=============
+
+Set the following parameters and reboot the autopilot.
+
+:ref:`AHRS_EKF_TYPE<AHRS_EKF_TYPE>` = 11 (External AHRS)
+
+:ref:`EAHRS_TYPE<EAHRS_TYPE>` = 12 (Xsens)
+
+For **UART** connection, also set, on the serial port used:
+
+- :ref:`SERIALx_PROTOCOL<SERIAL1_PROTOCOL>` = 36 (AHRS)
+- :ref:`SERIALx_BAUD<SERIAL1_BAUD>` = 115
+
+For **SPI** connection (MTi 1-series), set:
+
+- :ref:`EAHRS_OPTIONS<EAHRS_OPTIONS>` = 16
+
+The ``EAHRS_OPTIONS`` bits used by the Xsens driver are:
+
+============  =====  ===================================
+Bit           Value  Meaning
+============  =====  ===================================
+3             8      Sensor mounted facing downward
+4             16     Use SPI instead of UART
+============  =====  ===================================
+
+For example, a downward-mounted sensor on SPI is ``EAHRS_OPTIONS`` = 24.
+
+.. note::
+
+   The External AHRS parameters may not be visible until ``SERIALx_PROTOCOL``
+   is set and the parameters are refreshed, or the autopilot is rebooted.
+
+Verification
+============
+
+After rebooting, the Mission Planner Messages tab should show the External AHRS
+initialising and the IMU and barometer being registered as external. Moving the
+sensor should cause the attitude shown on the HUD to follow in real time.
+
+Notes
+=====
+
+- The Xsens module performs sensor fusion onboard and provides the attitude
+  solution directly. Setting ``AHRS_EKF_TYPE`` = 11 configures ArduPilot to use
+  this external solution.
+- GNSS-enabled products additionally provide position and velocity to ArduPilot.

common/source/docs/common-external-ahrs.rst

@@ -16,6 +16,7 @@ Currently, ArduPilot supports these systems:
 - `Trimble PX-1 GSOF <https://applanix.trimble.com/en/hardware/trimble-px-1-rtx>`__
 - `VectorNav <https://www.vectornav.com/products>`__
 - `Kebni SensAItion <https://www.kebni.com/products/inertial-sensing/sensaition-imu-ins/>`__
+- `Xsens MTi Series <https://www.movella.com/products/sensor-modules>`__
 
 Setup and Configuration
 =======================
@@ -39,13 +40,16 @@ Refer to :ref:`common-external-ahrs-sensaition` for details.
 VectorNav
 ---------
 Refer to :ref:`common-external-ahrs-vectornav` for setup.
+Xsens
+-----
+Refer to :ref:`common-external-ahrs-xsens` for setup.
 
 MicroStrain
 -----------
 
     - :ref:`AHRS_EKF_TYPE<AHRS_EKF_TYPE>` = 11 (External AHRS)
 
-    - :ref:`EAHRS_TYPE<EAHRS_TYPE>` = 1 (VectorNAV), 2 (MicroStrain5), 5(InertialLabs), or 7(MicroStrain7)
+    - :ref:`EAHRS_TYPE<EAHRS_TYPE>` = 1 (VectorNAV), 2 (MicroStrain5), 5(InertialLabs), 7(MicroStrain7), or 12(Xsens)
 
 This will replace ArduPilot’s internally generated INS/AHRS subsystems with the external system.
 The MicroStrain system must be configured via `Sensor Connect <https://www.microstrain.com/software/sensorconnect>`__ before use.
@@ -111,3 +115,4 @@ With higher baud rates, MicroStrain7 should be suitable for Copter and QuadPlane
 
     common-external-ahrs-vectornav
     common-external-ahrs-sensaition
+    common-external-ahrs-xsens