For Christmas 2014, a good friend of mine bought me a Raspberry Pi and I immediately searched the web for projects I could use it for. Skipping past the usual (and boring) media servers I found several mentions of “High Altitude Ballooning” and “Near Space Flights” and was immediately hooked. What I found mentioned electronics, radio, coding and much more which really appealed to the techy side of me, so I thought I'd give it a go. This page tells the story of my journey from complete novice, to still being a novice but having launched (and recovered) my maiden HAB flight. I won't attempt to replicate or replace all the existing excellent advice already available, but will add my own tips based on my experiences.
If you're reading this, you've already found the U.K. High Altitude Society (UKHAS). Their website has a ton of useful information, most of which is in the wiki and I used this site extensively for research. Secondly I strongly recommend visiting the IRC channel #highaltitude to speak with UKHAS members and ask questions. Everybody is really friendly and without them I would've made many mistakes. Thirdly, I found Dave Akerman's website a great resource too and Dave is often on IRC giving advice. Some of the most useful links I found as a novice are shown below:
From day one I decided I would always try to “build my own” rather than buying off the shelf. To me, the journey was just as important as the end goal so I wanted to enjoy the process of designing and building most things myself. So I discounted pre-built tracking devices immediately. I started by listing my primary objectives:
I have hardly any electronics experience other than wiring the odd plug so decided I should brush up a bit. I bought an “electronics for dummies” book and found it an excellent way to learn the basics. There are many free websites with similar content. When building your own tracker you need a basic knowledge of things like voltage, current, resistance, Ohms law and circuit diagrams. I also taught myself how to solder as this is needed for both the tracker and also some antenna work. Being new to electronics I needed to invest in several pieces of equipment such as a soldering iron, solder, breadboards, wire etc.
I decided to first focus on my tracker, the thing that would report the position of my flight and hopefully allow me to find it again once landed. My tracker would comprise of:
I quickly realised that the Raspberry Pi I had been bought wasn't best suited to the job. Whilst it would work, it was a bit big and heavy and also operated at 5V which meant a bigger battery pack would be needed. I decided on using an Arduino based solution that could operate at 3.3V and eventually chose the Arduino Mini Pro 8MHz 3.3V as my microprocessor. I could now look for components to work alongside my microprocessor and needed to choose items that worked at 3.3V. I also need to ensure any components worked ok at low temperatures as payloads can go down to -30 or lower when up high! My final shopping list for my tracker looked like this:
I ordered the GPS and radio items from HAB Supplies (Now Uputronics) and the rest from SparkFun, both of which provided great customer service with fast shipping.
My main piece of advice is to download and read the datasheets for all your components before you start wiring things up. They contain vital information about voltage/current requirements and what pin is used for what. As with most hobby projects, I started with an empty breadboard and my first job was to get the Arduino microprocessor onto the breadboard. I soldered 2 strips of header pins onto the Arduino board and pushed it into my breadboard. I then connected the FTDI breakout board to the Arduino to allow me to connect my laptop via USB.