A new GPS arrived today, all the way from 3DRobtics, as a replacement for my previously dead on arrival GPS unit. This time around the GPS worked as soon as it was plugged in and even started acquiring satellites from indoors.

For this project a constant data communication will be needed from the vehicle and its payload to a ground station. Therefore, a telemetry radio needs to be present. Fortunately, the APM 1 kit discussed earlier makes provision for a telemetry module. The telemetry modules I opted for was from 3DRobotics running at 433MHz 100mW. Due to ICASA regulations, these radios can only be used at 8mW maximum. This should be more than enough.

The flight controller is the brain of the vehicle and will contain most of the essential sensors.  To save time I opted for a Ardu-Pilot Mega 1.0. The main reason why I opted for the 1st generation and not the newer second generation is to have the option of replacing the 8 bit micro-controller with a 32 bit variant in the future.

Assembly of the APM 1.0 kit was rather easy, but took a while to solder all the connections. Hereafter, the flight controller was connected to its Mission Planner software, which confirmed proper working of the gyros, accelerometers and barometer. With some dismay the kit did not come with the magnetometer and will therefore still need to be acquired and tested later on.

One disappointment, however, was that the Mediatek GPS that came with the kit was dead on arrival. When connected to the APM board the 3D fix blue light came on and stayed on while the mission planner displayed no GPS. When going into the command line interface of the mission planner to test->GPS the only output was a constant string of G!G!G!G!. After confirming all connections from the GPS module on the adapter to the micro-controller as well as a 3.2V output on its regulator I used a FTDI cable to directly communicate with the GPS module. Hyper terminal showed that there was no data coming from the module itself. Thereafter I tried flashing the module with its own software which kept giving me a BROM_CMD_START_FAIL error. Luckily Carmen at 3DRobotics offered great support and shipped another module immediately.

The NXF-4 frame was bought from Netram in Durban (now in Cape Town), South Africa. It took 24 hours from order to delivery which I was quite impressed with. After it was delivered it took me a couple of hours to assemble with some spare parts. All in all the frame feels sturdy and has an interesting colour scheme. I will, however, be exchanging all of the nuts with some more reliable lock-nuts.