Adding a u-blox MAX-7 GPS module

• u-blox MAX-7 GPS breakout (we have one from HAP Supplies)
• KDE Marble built with Python bindings

These instructions are valid for Ubuntu 13.10 but similar steps should work with other distros.

• Attach the u-blox beakout to the expansion header by connecting the following pins (breakout → Crazyflie expansion header):
  • GND → DGND (pin 17)
  • VCC → VCC (pin 15)
  • TXD → TX (pin 5)
  • RXD → RX (pin 3)
• Since the Python bindings for Marble isn't built by default you will have to build Marble from source and enable these (instructions taken from here)

sudo apt-get install python-sip-dev python-qt4-dev kdelibs5-dev python-kde4

git clone git://anongit.kde.org/marble.git ~/marble/sources -b KDE/4.12
mkdir -p ~/marble/build
cd ~/marble/build
cmake ~/marble/sources -DCMAKE_BUILD_TYPE=Release -DEXPERIMENTAL_PYTHON_BINDINGS=TRUE -DCMAKE_INSTALL_PREFIX=/usr/local
make
sudo make install

• Make sure you have the correct firmware/software (the firmware is on the gps_ublox_dev branch and the client is on the gpstab branch)

There's no assisted GPS or battery backup so every time the Crazyflie is powered on the GPS module does a cold-start, which a while to get a fix. During ideal conditions it should be 42 seconds (according to datasheet) but during testing we have seen times closer to 4-6 minutes. The plan is to improve this in the future by implementing assisted GPS (downloading almanac on the PC and transferring via CRTP).

Getting a position fix will not be as easy as with your phone, so make sure to be outside (or at least stick the Crazyflie a couple of meters outside the window).

If you don't have a GPS module you can still use the DebugDriver which will send fake latitude/longitude/altitude to the UI.