This rather simple post is about integrating the GPS and telemetry radio (often called a 3DR radio, which is a company that makes them. It's kind of like calling all telephones GrahamBells...).
I used a UART breakout board to do this, which made it spectacularly easy, if you ignore the silliness of me frying the VCC line to the serial connector.
You do not have to use a UART breakout board! You can simply modify the cable harness between your flight controller and your GPS & radio. I chose the easy way (UART breakout) for this prototype. Certainly you do not have to, but it was terrifically easy with it. When I got the proper power to it (5V), it was as simple as plug it in and wait for a GPS fix.
It was just as easy for the telemetry radio. It was super easy, as I had already supplied 5V to the connector via the bus wire from the I2C port. I had a concern about pulling so much power through one pin, but it's not on the Atmel AVR, so it should be fine. Anyway, I simply installed the driver for the 433 MHz telemetry radio on my Windows 7 laptop, told Mission Planner that I was using a 3DR, and tried to connect. I neglected to adjust the baud rate the first time, but once I set it to Autodetect, the baud rate adjusted and everything worked just fine. So suddenly, I am able to get a 3D GPS fix, and use remote telemetry with Mission Planner with minimal effort. I can move my quadcopter around and see the results on my laptop without a physical tether. We're getting somewhere. This is awesome.
Here's a picture I found somewhere on the web showing the overall idea:
The next step is to mechanically integrate the boards. See you next post.
