Add documentation for new Septentrio-specific driver

As the Septentrio driver has moved from the PX4 GPS drivers repository
into the main codebase and received new parameters and features, the
documentation needs to be updated to reflect them.

en/SUMMARY.md

@@ -274,7 +274,8 @@
       - [Holybro H-RTK Unicore UM982 GPS](gps_compass/rtk_gps_holybro_unicore_um982.md)
       - [Locosys Hawk R1](gps_compass/rtk_gps_locosys_r1.md)
       - [Locosys Hawk R2](gps_compass/rtk_gps_locosys_r2.md)
-      - [Septentrio AsteRx-RIB](gps_compass/septentrio_asterx-rib.md)
+      - [Septentrio GNSS Receivers](gps_compass/septentrio.md)
+      - [Septentrio AsteRx-m3 Pro](gps_compass/septentrio_asterx-rib.md)
       - [Septentrio mosaic-go](gps_compass/septentrio_mosaic-go.md)
       - [Trimble MB-Two](gps_compass/rtk_gps_trimble_mb_two.md)
       - [CubePilot Here+ (Discontined)](gps_compass/rtk_gps_hex_hereplus.md)

en/gps_compass/septentrio.md

@@ -0,0 +1,190 @@
+# Septentrio GNSS Receivers
+
+PX4 autopilot supports Septentrio GNSS receivers based on the mosaic-X5 and mosaic-H receiver
+modules. It has [parameterized](../advanced_config/parameter_reference.md#septentrio) automatic
+configuration to fit different use cases. The output is processed by the Septentrio driver in PX4
+autopilot and made available to the rest of the system like the MAVLink and EKF modules. Certain
+receivers are recommended for autopilot applications because of their physical or technical
+properties, including:
+
+- [AsteRx-m3 Pro](https://www.septentrio.com/en/products/gps/gnss-boards/asterx-m3-pro)
+
+Dual-antenna, ultra-low-power GNSS rover receiver with support for heading.
+
+- [AsteRx-m3 Pro+](https://www.septentrio.com/en/products/gps/gnss-boards/asterx-m3-pro-plus)
+
+Dual-antenna, ultra-low-power versatile GNSS rover and base receiver with support for heading.
+
+- [mosaic-go](https://www.septentrio.com/en/products/gps/gnss-receiver-modules/mosaic-go-evaluation-kit)
+
+Single-antenna evaluation kit with support for L5 frequency band, based on the mosaic-X5 GNSS
+receiver module.
+
+- [mosaic-go heading](https://www.septentrio.com/en/products/gps/gnss-receiver-modules/mosaic-h-evaluation-kit)
+
+Dual-antenna evaluation kit with support for heading, based on the mosaic-H GNSS receiver module.
+
+## Supported Features
+
+- RTK positioning using corrections over MAVLink from a ground control station
+- Dual-antenna heading with mosaic-H-based receivers
+- Moving base heading with two single-antenna receivers
+- SBF logging to internal storage on the receiver
+- Logging of all communication with the receiver to internal storage on the flight controller
+- Automatic baud rate and port detection
+- Automatic, parameterized configuration for all features
+- Status and health monitoring from a MAVLink console
+
+## Quick Start
+
+For the physical connection between Septentrio GNSS receivers and flight controllers, have a look at
+the hardware-specific guides for [mosaic-go receivers](septentrio_mosaic-go.md) and [AsteRx-m3
+receivers with a robotics interface board](septentrio_asterx-rib.md).
+
+A few things are required for PX4 autopilot to support Septentrio receivers. First of all, the
+firmware you load on your flight controller needs to contain the Septentrio driver. This should be
+the case for most available official builds. You can confirm this by opening QGroundControl,
+connecting to the flight controller running the firmware you want to use and checking whether the
+"Septentrio" parameter group is available in the parameter configuration screen.
+
+![Septentrio Driver Parameters](../../assets/hardware/gps/septentrio_sbf/septentrio_driver_parameters.png)
+
+Next up, you need to tell PX4 autopilot which serial port the receiver is connected to. This is
+often indicated by a label above the port on the flight controller you are using. If you plugged in
+the receiver into the port labeled "GPS 1", you need to set the `SEP_PORT1_CFG` parameter to `GPS
+1`. You also need to make sure no other driver is configured to use this serial port. By default,
+the `GPS` module will be configured to use the `GPS 1` port, so **make sure to set `GPS_1_CONFIG` to
+`Disabled`**.
+
+After those two steps, the flight controller should automatically configure the connected
+receiver(s) using the parameters you set, after which the position will become visible in
+QGroundControl and the GPS icon will display general status information.
+
+## Serial Configuration
+
+Septentrio GNSS receivers make use of a serial connection to the autopilot. There are two types of
+parameters available to configure this connection. First there are the parameters under the
+"Septentrio" group which can be used to select the physical port the receiver is connected to. If
+for example one receiver is connected to the port labelled "GPS 2", then you need to set
+`GPS_1_CONFIG` to `GPS 2`, meaning the main receiver (hence the 1 in `GPS_1_CONFIG`) is connected to
+the second GPS port (therefore `GPS 2`).
+
+The baud rate used for the serial connection is also configurable. It can be set to any of baud
+rates supported by Septentrio GNSS receivers. The driver will always detect the baud rate of the
+receiver and if a baud rate is set, it will configure the receiver to use this one. If none is set,
+the driver will use the current baud rate of the receiver. Higher values make for a faster
+connection, but may fail if there is lots of interference or the cabling is of poor quality. Using
+other baud rates will not work and the driver will fall back to a default of `230400`. When using
+RTK positioning or higher receiver output rates, values above `460800` are recommended. Supported
+ones are:
+
+- `57600`
+- `115200`
+- `230400`
+- `460800`
+- (`500000`)
+- (`576000`)
+- `921600`
+- (`1000000`)
+- (`1500000`)
+
+> Baud rates between parentheses are non-standard and should be avoided.
+
+## Automatic Configuration
+
+Normally the driver automatically configures the connected receivers as long as the ports have been
+set correctly. Some users may wish to perform additional changes to their configuration, in which
+case the driver should not automatically configure it. This can be changed using the
+`SEP_AUTO_CONFIG` parameter. Keep in mind that the driver always detects the baud rate and receiver
+port to ensure correct operation. When the baud rate parameter is configured the baud rate will also
+be configured, regardless of whether automatic configuration is disabled.
+
+Multiple parameters are available to change how the receiver is configured. `SEP_CONST_USAGE` can be
+used to choose which constellations to include/exclude from PVT computation. `SEP_OUTP_HZ` changes
+the frequency of PVT data output to the flight controller. `SEP_STREAM_MAIN` and `SEP_STREAM_LOG`
+change which streams are used for the main and logging output from the receiver. These can be
+changed when you already use the default streams for other purposes. Make sure to use two different
+streams. Using the same one for both will prevent logging from starting correctly.
+
+## GNSS-Based Heading
+
+Heading determines the orientation of the vehicle. GNSS-based heading allows for heading without
+relying on an internal compass, which might encounter interference from the motors and other factors
+on a vehicle. There are two methods to use Septentrio GNSS receivers for GNSS-based heading. The
+first is to use a receiver based on the mosaic-H receiver module, like the mosaic-go heading,
+AsteRx-m3 Pro and AsteRx-m3 Pro+. Heading will work automatically when one of these is connected and
+has two antennas attached. The other is to use two separate receivers attached to two ports, each
+with one antenna. In that case the `SEP_HARDW_SETUP` parameter has to be set to `Moving base` and
+the main receiver (set by `SEP_PORT1_CFG`) will act as the rover. To switch rover and base in the
+moving base setup, switch `SEP_PORT1_CFG` and `SEP_PORT2_CFG` or physically swap the connected
+receivers.
+
+It is important that the antennas are positioned at least 30 cm apart for a stable heading result.
+In a normal setup, the main antenna is behind the auxiliary one. If another setup is used, the
+`SEP_YAW_OFFS` value needs to be changed accordingly. If the antennas are not at the same height,
+the `SEP_PITCH_OFFS` value needs to be changed.
+
+## Logging
+
+There are two ways to log data for Septentrio GNSS receivers. The first is to log certain SBF
+(Septentrio Binary Format) blocks internally on the receiver. The second is to log incoming,
+outgoing or all communication between the flight controller and receiver on the internal storage in
+the flight controller.
+
+### Internal Receiver Logging
+
+The driver can configure the receivers to log their data to internal storage. That data can be
+valuable for troubleshooting in case something goes wrong. There are three parameters to change the
+logging configuration. `SEP_LOG_HZ` sets the frequency of the internal logging. It also allows to
+disable logging. `SEP_LOG_FORCE` decides whether the driver overwrites existing messages on the
+logging stream (`Enabled`) or adds to them (`Disabled`). `SEP_LOG_LEVEL` sets the verbosity of the
+internal logging. There are four levels:
+
+| Level   | Blocks                                                     |
+|---------|------------------------------------------------------------|
+| Lite    | Comment+ReceiverStatus                                     |
+| Basic   | Comment+ReceiverStatus+PostProcess+Event                   |
+| Default | Comment+ReceiverStatus+PostProcess+Event+Support           |
+| Full    | Comment+ReceiverStatus+PostProcess+Event+Support+BBSamples |
+
+### Flight Controller Logging
+
+The driver can also log all communication from and to the receiver. That can be configured using the
+`SEP_DUMP_COMM` parameter. See [the logging guide](../dev_log/logging.md) for more information about
+reading those files.
+
+## MAVLink Console Usage
+
+The Septentrio driver can be fully used from the MAVLink console. This allows for driver startup and
+shutdown, receiver resets, status monitoring and parameter changes. It may also help when
+encountering problems as the console may print related error messages, pointing to the source of the
+problem. **Error messages are only displayed when the driver has been started from the console.**
+
+```sh
+# See help
+septentrio -h
+```
+
+```sh
+# Get current health and statistics
+septentrio status
+```
+
+```sh
+# Start the driver with a receiver connected on port `/dev/ttyS0` and
+# automatically configure it to baud rate 115200. Also use a receiver on
+# port `/dev/ttyS7` and use its current baud rate.
+septentrio start -d /dev/ttyS0 -b 115200 -e /dev/ttyS7
+```
+
+Three reset types are supported:
+
+- `hot`: Reset the receiver firmware but preserve the current configuration
+- `warm`: Reset the receiver firmware, preserve the current configuration but remove cached PVT data
+- `cold`: Reset the receiver firmware and use boot configuration, also remove satellite data like
+ephemerides
+
+```sh
+# Perform a hot reset on the connected receivers
+septentrio reset hot
+```