I happened to be digging through Google searches a couple weeks back, and I stumbled upon an amazing looking hack of the Coobro Geo. A regular here at Adafruit, Stephanie, has done some nice work with a custom Chronodot library, and other hacks of Adafruit products. Using the open source schematic of the Coobro Geo, Stephanie managed to strap on an Adafruit OLED, and a lipo battery she had laying around to create her own GPS tracking device. Here is how Stephanie describes it:

In a nutshell – I was thinking of making an arduino/gps device to help me track walks. I wanted to know the time and distance I was walking. When I saw your Coobro Geo project I realized that would be a perfect platform to build on.

For the LEDs, I’m using them to indicate the GPS accuracy – if there’s no signal or it’s too poor to use, the three LEDs flash. As the signal gets better, it goes to two, then one, then if the signal is excellent, none of the LEDs blink. The OLED screen displays some basic stuff on the top, like lat, long, UTC time. The push-button toggles the ‘track’ mode, so once it’s on and has a fix, one push starts it tracking – so it starts counting time, and every 10 seconds it checks how far it’s travelled. This info is displayed on the lower half of the screen. A second push of the button stops the tracking, so you can see the total distance covered, the time, and the calculated average speed. And finally, a long-push of the button clears the data.

I haven’t finished working on it yet, I was also planning on having it save the readings to the EEPROM, like every 10 seconds (or once a minute or whatever) I’d have it save the lat lon and utc stamp. Then I could dump that info at home and play it back over a map or something.

I am using a LiPo for power, I had one I’d pulled out of a dead handheld gaming device which was almost exactly the same size as the Coobro PCB. I added a JST connector so I can just unplug the battery and plug it in to a charger when I need to top it up.

I left off one of the distance LEDs because I wanted to keep the I2C pins available “just in case” and left the other LED off because… it had to be symmetrical! hehe. To connect the OLED I used several of the directional LED pins, but I did wire three of the direction LEDs up – they’re just hidden beneath the screen. The screen is held on by the wires that I used to connect it, most of which are on the left-hand side. On the right hand side there’s two wires that are not used, other than to hold the screen down. So if I needed to access the uC for any reason, I only have to desolder two wires and the OLED will fold away to one side.

Finally, I wired the power switch for ‘always on’ and replaced the jumper with the power switch, so switching it to ‘battery’ turns it on and switching it to the ‘ftdi’ side turns it off (unless you have the ftdi plugged in of course). The downside is that this means the GPS does not get that backup power to keep its settings. But I realized it would lose that every time I unplugged the battery to recharge it, so I figured it wouldn’t matter if it had to coldstart each time. It only takes about 2 minutes to get a lock and solid signal even indoors.

I totally love that gps module by the way. It’s my first experience working with a gps and it blows me away how sensitive it is. I found it was ‘too talkative’ though so I figured out how to send it the NMEA control info to have it only send the two sentences I required.

I’ve pasted my sketch info below. Like I said, it’s a work in progress…

Cheers!

-Stephanie

p.s. Just remembered I had to modify the tinygps library. For ‘signal quality’ I am actualy using HDOP (horizontal degree of precision) but the tinygps library was ignoring that value. It’s a bit of an arbitrary thing, but the lower-the-better and I figured i’d want to know if it was accurately tracking my walk or not.  I’ve included my modified library as well as the sketch… I also increased the buffer in the new soft serial library, as I found it was having trouble keeping up with the gps.

p.p.s. I think there’s a bug in the speed calculations, but haven’t had time to finish analyzing that – work has been crazy busy the last few weeks.

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Coobro Geo owner and active user Gerard (call sign DL8SEL) has been pumping out updates to the Coobro Geo code and he is finally ready to show it off.  We are blown away with what Gerard has done here.  Just listen to this long list of new features he has developed:

1. 32 breadcrumb coordinate storage in eeprom
2. 32 geo coordinate storage in eeprom
3. Active geo and breadcrumb coordinates shown on the distance LEDs in binary
4. Activity logging: every time you turn on the device it logs the date/time/location of your start (10 revolving data logs)
5. Read and write coordinates and breadcrumbs via serial communication
• a write command allows to store breadcrums lat/lon in a specific location in the table
• a read command shows all non-zero breadcrums lat/lon
• structure to write: w b17 +00.000000 +00.000000 *
6. When you turn on the device, it will flash the software version in binary
7. When you turn off, then turn on the device, it will return to the last coordinate you were navigating to
8. The close up distance display can be changed easily with a #define macro (from 5 to 10 or xx meter if you want to use it in a car)
9. When you turn on the device, it will transfer all wp of the program code into the corresponding eeprom wp storage area if the corresponding storage field is empty

A special thanks to Gerard for all of his hard work on the code!  This is exactly why our kits will always be open source.  Download Gerard’s updated code on GitHub.

Watch the video below to see the official unveiling of the Coobro Geo on the Adafruit.com show and tell.  Definitely watch the whole video if you haven’t seen one of Adafruit’s show and tell’s before.  If you want to fast forward to me showing off the Coobro Geo, skip ahead to the 7:20 mark.  Make sure to check out the show and tell every Saturday night at about 8:30PM CST.

The Coobro Geo is a project that started off as a way for me to learn more about designing and building Open Source Electronics.  First, let me explain what the Coobro Geo is, then after the the jump, I will give a little explanation of the process that I went through to get to where the project is today.

The Coobro Geo is an easy to assemble GPS navigation kit.  Upload coordinates, turn it on, and the Coobro Geo will help you navigate to any destination on earth by using LEDs to show you the correct direction and distance remaining.  Before you leave on your quest, press and hold the breadcrumbs button and the Coobro Geo will remember your location and help you navigate back.  Store up to five pre-entered destination coordinates and five breadcrumbs, or modify the open source code and store as many coordinates as you want.

Use the Coobro Geo to help you find geocaches, store and navigate between hot fishing spots, complete a scavenger hunt, or simply help you find your car after a hike.  You can pick up a Coobro Geo of your own here.

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