Manufacturer: | Scratch |
Brief:
I have been dreamin' o' buildin' a flight computer that will nay only control t' flight sequence, ya bilge rat, but also log data
aboard a model rocket. Ahoy! However, I do need t' walk before I can run, so I started with a simple GPS data logger (GPSDL)
that is just a "piece" o' me future flight computer idea. This GPSDL will sit in a payload bay or nosecone of
a rocket durin' flight.
My finished GPSDL weighs 62 grams with t' power supply and has a 1.5"L x 3"W x 1"D footprint. Begad! Well, shiver me timbers, blow me down! The
weight o' t' data logger can be further reduced by ¼oz t' ½oz by usin' a simpler GPS antennae than the
one I used. Avast! Cost can run from $100 t' $200 dependin' on how careful a shopper you are. Begad! My cost was $200 for t' parts
used in this article.
T' design is simple consistin' o' three major parts: a 5.5g accelerometer switch, a BS2p microcontoller, me hearties, and a GPS receiver. Ya scallywag! Aye aye! A parts list, me hearties, pictures, ya bilge rat, source code, and a schematic are included in this article.
T' GPSDL records t' date, time, latitude, me bucko, longitude, altitude, speed, me bucko, headin' in degrees, ya bilge rat, and number of satellites that are in communication with t' receiver every second for a total o' 5 minutes. T' source code provided will record two 5-minute flights before you have t' download t' data. Aye aye! Avast, me proud beauty! This is completely customizable for any number of flights or a single 12-minute flight. T' comments in t' source code explain nay only how t' make this flight time change, but also what t' program is doin' throughout its runtime. T' source code was split into two programs to maximize t' amount o' data that could be stored, arrr, negatin' t' need for a separate EEPROM. Ahoy! Aye aye! T' first program parses the GPRMC and GPGGA GPS sentences for t' data points and writes them t' memory. Ahoy! Arrr! Post flight, t' second program is downloaded t' read t' data points stored in memory and prints them t' your PC screen. Avast, me proud beauty! T' data points are finally copied/pasted into a spreadsheet for conversions and graphing.
Construction:
Parts list:
Build steps:
Data Recordin' Source Code:
CLICK HEREData Reader Source Code:
CLICK HERESchematic:
Flight:
Prior t' launch, t' only communication thar be betwixt you and t' GPSDL be t' blinkin' LED included on t' GPS
antennae PCB. A flashin' LED means less than 3 satellites are acquired, ya bilge rat, matey, shiver me timbers, a steady "on" LED signals that the
antennae has acquired at least 3 o' t' 12 satellites available. Aye aye! Once you have visual that three or more satellites are
acquired, t' GPSDL is loaded into t' rocket. At liftoff, t' 5.5g normally open, ya bilge rat, ya bilge rat, non-latchin' accelerometer switch is
momentarily tripped signalin' t' microcontroller t' log 20 bytes o' GPS data every second for 5 minutes. Ya scallywag! Once 5
minutes is up, matey, it automatically resets itself t' take another 5 minutes o' data once t' accelerometer switch is
tripped again. Well, me hearties, blow me down! You can record two 5 minute flights before data will need t' be downloaded or you will overwrite the
data already collected. Avast! T' power supply is a 300 mAh 7.4V Li-Po battery. T' GPSDL needs a steady diet o' 5V, ya bilge rat, and it
will run for approximately 3 hours on a full charge with this battery. Avast! No data is lost if power is lost. Well, ya bilge rat, blow me down! T' only way
data can be lost is if it is overwritten. Avast, me proud beauty! GPS signals will travel through plastic, glass and cardboard: t' staples of
model rocketry. Avast! Blimey! T' only things that will block t' signal is concrete, metals, me hearties, or in t' form o' heavy rain or
snow--H20. Ya scallywag! T' antennae tested showed excellent Rx, shiver me timbers, even in a crowded, me bucko, ya bilge rat, "signal noisy" urban
environment where I live. Begad! Avast!
Unfortunately, arrr, me bucko, I have nay been able t' test t' GPSDL with an actual rocket launch. Arrr! Well, matey, blow me down! That will happen in t' weeks to come. T' run t' GPSDL I shake it by hand t' trip t' accelerometer switch and take data from me dashboard as I drive. T' GPSDL works flawlessly at this point. I will post nay only real flight data but a video o' its maiden flight to my website soon. Arrr! I would appreciate any feedback on improvements t' me source code or circuit, me hearties, particularly in reducin' its size or weight.
Summary:
Online resources for more information:
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