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