I have been dreaming of building a flight computer that will not only control the flight sequence, but also log data aboard a model rocket. But I do need to walk before I can run, so I started with a simple GPS data logger (GPSDL) that is just a piece of my future flight computer idea. This GPSDL will sit in a payload bay or nosecone of a rocket during flight.
My finished GPSDL weighs 62 grams with the power supply and has a 1.5 inch W x 3 inch L x 1 inch D footprint. The weight of the data logger can be further reduced by .25 to .75 oz. by using a simpler GPS antennae than the one I used. Cost can run from $100 to $200 depending on how careful a shopper you are. My cost was $200 for the parts used in this article.
The design is simple consisting of three major parts: a 5.5g accelerometer switch, a BS2p microcontoller and a GPS receiver. A parts list, pictures, source code and a schematic are included in this article.
The GPSDL records the date, time, latitude, longitude, altitude, speed, heading in degrees and number of satellites that are in communication with the receiver every second for a total of 5 minutes. The source code provided will record two 5 minute flights before you have to download the data. This is completely customizable for any number of flights or a single 12 minute flight. The comments in the source code explain not only how to make this flight time change, but also what the program is doing throughout its runtime. The source code was split into two programs to maximize the amount of data that could be stored, negating the need for a separate EEPROM. The first program parses the GPRMC and GPGGA GPS sentences for the data points and writes them to memory. Post flight, the second program is downloaded to read the data points stored in memory and prints them to your PC screen. The data points are finally copied/pasted into a spreadsheet for conversions and graphing.