the sky and that the GPS was
facing up. After a bit of tinkering, I
gave up and sat down to read
through the documentation.
The thing I had missed was
that the GPS will not be powered
if the flight controller is only
powered by the USB connection.
After connecting the flight
controller to the flight battery, I
was able to get a lock pretty
quickly. When doing the steps that
follow, I found it really nice to
have a long USB extension cord. I
ended up with a 15 ft ( 4. 6 m)
cable. This let me put the quad on
my patio table while sitting
comfortably at my desk inside and
experimenting with the
configuration.
Once you’ve opened the
LibrePilot Ground Control Station (GCS) software, click on
the hardware configuration icon. You’ll see a view of the
flight controller printed circuit board (PCB) with a drop-down
selection box by each hardware connection port. Find the
main port and select GPS. Set the baud rate to 38400
(Figure 3). Once all of the boxes are correctly set, click save.
If you now go back to the flight data tab and look in
the lower left, you will see a panel of virtual annunciators.
These are those status lights you see in cockpits and
industrial control rooms. The GPS annunciator tells you if
you have communications with the GPS unit and its lock
status. If you have your quad outside with the GPS upward
facing in a clear sky view, the annunciator should turn
green in a minute or two (Figure 4). Hovering the mouse
over any annunciator gives a more detailed description of
its status. If you don’t get a GPS lock, make sure that the
green LED on the underside of the GPS is lit, double-check
that you saved the settings to the flight controller, and
make sure you’ve got a good view of the sky.
When I was first playing with this, I was frustrated that
the maps did not seem to load in the GCS. It turns out the
application programming interface (API) LibrePilot uses to
download the maps from Google has been modified and
they have corrected the code for the next release. For now,
you can click on “Edit Gadgets Mode” in the “Window”
menu (Figure 5) and set the map widget to use maps from
SERVO 09.2016 33
Figure 3. Configuring the GPS is as simple as setting up the
main port as a 38400 GPS unit with the UBX interface. This
page is under the hardware tab in the LibrePilot interface.
Figure 4. The annunciator panel shows the status of all the important systems on the
quad. Wait for the GPS indicator to become green to confirm your flight controller
has a positive lock with enough satellites.
Figure 5. The layout of the flight data tab is very
customizable. Selecting “Edit Gadgets Mode” from the
“Window” menu will let you swap in and out various
information displays.
