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Zubax GNSS can be set up for use with any other UAVCAN-enabled system in a very similar way.
Aside from Zubax GNSS itself and the Pixhawk it will be connected to, the following parts are needed:
Also, in order to configure the board, either of these tools are needed:
The parts listed above in bold font can be purchased from Zubax distributors. Alternatively, customers can choose to manufacture the needed cables/plugs on their own in order to suit some custom needs, in which case they should refer to the relevant documentation for details.
If you’re using APM, the default configuration should be changed manually as follows:
uavcan_node_idneeds to be set to an appropriate unique value to avoid Node ID conflicts
Connect the interface, open CLI, then execute:
cfg set uavcan.node_id 50
This command will set the Node ID to 50.
Save the configuration into the non-volatile memory:
An error like
ublox: Invalid checksum may appear,
which is expected because non-volatile memory IO disrupts other IO operations.
Now, restart the device in order to apply the new parameters:
Configuration is complete.
UAVCAN is supported in the following APM firmwares:
UAVCAN driver is enabled in APM by default, but it is necessary to change some configuration parameters to make APM listen to external UAVCAN-connected sensors. The following chapters assume that Mission Planner is installed on the user’s computer, and that Pixhawk is otherwise properly configured.
Remember that it may be necessary to restart Pixhawk before the changes take full effect.
In order to make APM receive measurements from an UAVCAN-interfaced GNSS receiver, set the parameter
GPS_TYPE to 9.
In order to make APM receive measurements from an UAVCAN-interfaced compass, open the tab
Mandatory Hardware →
Compass. On the displayed page:
ROTATION_NONE. You may need to select a different rotation if the arrow printed on Zubax GNSS is not aligned with vehicle’s longitudinal axis.
Don’t forget to perform compass calibration when done.
APM does not have proper support for external barometers, so proposed solution is a bit hackish, but it still works. This modification is not required if external barometer is not needed. Also, make sure that the barometer is enabled on Zubax GNSS.
Power off the Pixhawk, extract its microSD card and mount it on a computer.
Create a file
etc/rc.txt on the card and put the following script in it:
# uORB will be started again by the main init script later, it's OK if uorb start then echo "ext: uORB started" if uavcan start 1 then echo "ext: UAVCAN started" else echo "ext: Could not start UAVCAN" fi else echo "ext: Could not start uORB" fi # This delay allows UAVCAN to pick external sensors before internal ones sleep 8
Insert the card back into Pixhawk.
Done, now the Pixhawk will be using barometer installed on Zubax GNSS, provided that Zubax GNSS was connected to the bus at the time of boot; otherwise it will fall back to internal barometer.
Set the configuration parameter
UAVCAN_ENABLE to 2, then reboot.
Please refer to the Pixhawk documentation for extra info.
Since Zubax GNSS can be powered directly from the bus, the electrical connections are quite simple:
Now the setup is ready to work.