Jacket Positioning System: JPS
Well, as titles go, I guess this one is strange. But I shall digress and jump right in anyway.
A while ago, one of my friends and I came up with a silly idea while night orienteering (challenging enough in the day). We couldn’t see anything, so we had a person walk out ahead of the compass man and wave around a chem stick like a silly person until they were properly aligned with the compass bearing. This spawned the concept of embedding a few LEDs into a jacket for reading maps and showing position. Our minds didn’t stop there, however, and we quickly advanced to the idea of having an entire GPS system integrated into the jacket. Thus, the Jacket Positioning System, or the JPS.
It took me a while to get started on it, as my friend isn’t technologically gifted. I immediately knew where I was going to source my parts, from SparkFun.com (you will see their logo all over most of the stuff), however, it took me forever to compile a list. Finally, it came down to this:
- Straight pin headers
- Serial White-on-black screen (3.3v)
- FTDI Basic 3.3v
- Arduino pro-mini 8MHZ (3.3v)
- 6Ah 3.7v LiPo battery (1s3p)
- Wombat Proto-board
- Awesome 66 channel GPS reciever (3.0-4.2v)
- And other assorted bits
You’ll quickly notice one thing about this list of parts. All things on this list can operate directly off the nominal voltage range of a LiPo battery. Why, you ask? Well, I didn’t want any of the stupid inefficientness of voltage boosters/regulators. As good as they have become, they aren’t 100% efficient. And since I was going for max battery life, I went for max efficiency. So, that’s the partslist, how’d I go about it?
Well, I hadn’t ever really done anything like this before (I had tinkered with Arduinos a bit, but that’s about it), so I just started building. I started with the Wombat proto-board (a wholly awesome product) by putting down the buttons and JST connector for the battery. It dawned on me right after that happened that my current soldering iron (a “wonderful” RadioShack iron) just wouldn’t cut it. So I fired more money at SparkFun and ordered their advanced tool kit. I don’t mean to sound all SparkFun fanboy-ish, but really, it is an awesome list of parts all of which you do need to get started.
BOOM! Funny side story time. Just about the most useful tool in there so far has been the pair of tweezers. They have literally saved me almost $100. They brought back an Arduino UNO from the dead by pulling out a 0.1″ pin from the RX header, and they saved my screen when a solid-core wire broke off in one of the terminals. Tangent done, back to the main story.
So, I got it all built, eventually, after discovering a few useful things about perfboards, like how awful solder trails look. Seriously, don’t do it. Anyway, the final result was actually quite interesting. I had a working little GPS thingy that could fit in a jacket (however the buttons cannot be reached at this point, it is still all on one board) and display Lat/Long, Speed/heading, Altitude, time/date, and RAM free (that was just for fun, the last one). Enough talking, Pics or it didn’t happen, right?
Right now, it’s pretty simple. It only does those functions, but with the help of the truly fantastic TinyGPS library, I have a destination function in the works. It goes for almost a week on one 6Ah LiPo battery… with the backlight on. If you were to turn off the backlight… It would probably run for almost a month.
My future plans for this device are pretty simple, actually. I hope to design and manufacture a few PCBs for it, and get an actual case for the screen (waterproof, shock resistant, the whole 9 yards) and a 5 position joystick for the control input. I also want to build a solar charging station for it — a portable one, mind you. Then I hope people will buy them, but I doubt it.
Anyway, thanks for reading, I know it was long and rambling, but whatever — I do my best.