I, too, am a big fan of the SparkFun kit. I bought the newer V2.4 (20-channel SiRFStar III) just a few weeks ago:
http://www.sparkfun.com/commerce/product_info.php?products_id=8237
Do yourself a favor and don’t waste money on the kit like I did. First, one of the wires came off the battery connector, and as far as I could tell, you cannot remove the pin without damaging it (so if you manage to put it back into the housing it may easily pop out). Luckily I had an extra connector. The included SD card is also a piece of junk; mine still works on a computer but is not recognized by the device.
I bought this to track my own road trips, because I refuse to pay for a device with a screen that has some stupid track log limit. I successfully tracked a 5 day trip with one sample per second (turning the unit off at night) without a hitch.
Since I also recently got a Nikon D200, I got excited about using GPS with that. Luckily SparkFun’s product exposes a serial port for reprogramming the device. I bought their CMOS to RS232 level converter and programmer (bootloader):
http://www.sparkfun.com/commerce/product_info.php?products_id=714
Unfortunately the TTL input of the camera is not CMOS (3.3V) compatible (I would be surprised if it was stupid of me to think it would be). So I built a little MAX232 circuit to splice off the RS232 out of the bootloader board.
The firmware provided by SparkFun is quite limited, and requires some (I reckon simple) modifications to be recompiled with something other than the expensive suite they used (Crossworks). The perfect solution for me was this guy:
http://gpslogger.blogspot.com/
I contacted him and he was more than willing to enable the serial port output and the logging at the same time (v0.94a). Just after that he corrected a few minor issues and released v0.94b, but I’m still using 0.94a (more about that later).
So the whole setup allows me to log my position, have one TTL out for the camera, and one RS232 out for whatever else. There’s obviously a quick and dirty way to take that RS232 out and turn it into bluetooth if you happent to have an adapter (I did), but it requires some wiring to power the adapter and I ended up not having enough time to do it.
Now for the bad parts. This is a kit, and thus is sort of uncomfortable to use. To safely turn off the device without losing data, both firmwares require that you hit a stop button before you turn it off, which is a bit annoying because the power switch on the board is tiny (and mine has an iffy contact) so it’s more comfortable to just disconnect the batteries. The board itself only has two mounting holes, and the component layout is such that you can’t put anything bigger than a 2-56 screw in there or the head will hit something. Nowhere around here has standoffs with that thread. Once you add the bootloader/level converter, it becomes a nightmare, really. I also had the terrible luck of not being able to find a plastic prototyping box of appropriate size anywhere around here, so mine became a horrific concoction of rubber bands, poster tacking compound, and batteries—but if fits nicely in a removable pouch that attaches to my camera bag. Since I couldn’t get it really to any nice small size I went ahead and put two battery holders on it (I’m already carrying about 40 pounds of cameras anyway).
Because of the annoying layout of the GPS logger board, turning it off requires first reaching under the logger unit (on the left where you can just make out “Sandisk”), hitting the stop button, then pulling the battery connector (I don’t want to touch that switch anymore). I turned it off every night during the trip to backup the tracklogs in case the SD card failed, but with those 8 AA batteries I’m sure I could leave it on for a long time.
Overall I’m very happy with the functionality, but disappointed with the packaging. I used GPSBabel (http://www.gpsbabel.org/) to translate the NMEA sentences to a variety of formats, including KML. Now that I found this site, I will see about contributing some with this little device.
