This idea came up because GPS chips are cheap, and so are bluetooth chips, and I didn't feel like paying ~$100 for something I could do myself.

Deezums pointed me on to this chip (it took about 3 weeks to get here), and I used an HC-05 bluetooth module that I have from work, same one I used on my MS3. I thought that I would have to use a micro controller in the middle but the output of the GPS turned out to be exactly what most apps need. After a bit of configuration I was able to get it to work.

Also ordered this (thanks Schuyler) and will be testing it too.

I will be adding a small power supply mini-usb breakout and 3d printing a case. After I get that all done I will update this with a little how-to for people who want to follow suit.

Total cost so far:

$25 gps ($16 maybe)
$7 bluetooth
$2 mini-usb

$34 ($25 maybe)

 

Nice project. What are you using to log the data? Does it just send and log NEMA sentences? I think the GPS unit used on my project is the same one but I haven't gotten around to changing the refresh rate from the default 1Hz

 

It hooks up to any android app that supports NMEA protocols. So far tested with racechrono and harrys lap timer.

 

Got it. How long does it typically take you to get a satellite lock from a cold start?

Is there any support for an external antenna?

 

Haven't done a whole bunch of testing. Probably around 30 seconds.

No idea? Its a chinese gps breakout board with no datasheet. I only dug in far enough to find power and tx/rx pins. I'm going to make a case with a clear acrylic top and mount it to my windshield so I'm not to worried about the antenna.

 

hmm, i'm gunna order one of these and give the same plan a shot.

RYN25AI 10Hz UART Interface High Performance GPS Glonass Antenna Module Battery | eBay

Hoping i get just as lucky when it comes to microprocessor necessity.

 

Good find! I'm going to order one of them too. I'll compare the 2 and see if I notice any differences.

 

I'd pay $35 for that, provided it comes with caveman-proof instructions.

 

I don't want to commit to anything but if it works well and I don't run into any issues I will probably do a little group purchase. Gotta ask my boss what I would have to pay for 3d printing. Personal projects are free so I've never priced anything.

 

Hehe, thanks for being my guinea pig, I'm gonna go ahead and order one now :P

 

I'd use the ebay one. Bigger antenna. Better instructions.

 

which bluetooth module did you get? I'm thinking of doing a bluetooth accelerometer module.

 

HC-05. Phone accelerometers are a lot more accurate and fast than phone gps.

 

I was using the phones accelerometer, but now I have the phone mounted on a windshield mount. The vibrations make the data from the phone sensor pretty much useless.

 

Should consider not putting it in the windshield. You'll get lots of drops and shitty data if your roof goes between you and a couple satellites. This isnt noticable with 1hz phone gps, but its gets to be a problem when you're actually logging at 10hz. Best bet is on top of the hard top if you have one, or on the bit of metal just in front of the trunk.

 

Only phone is mounted on the windshield, the gps receiver is mounted on the roll bar, at the moment. So far no issues with gps reception encountered yet. But thanks for the tip, didn't think the soft top would mess with the gps signal so much.

 

GPS is typically line of sight. I will be testing out some options. So far once this module gets a fix its pretty hard to lose it.

 

Race Technologies tells you not even to put colored tape over the gps antenna for the DL1 because it can effect the signal. Black being the worse offender.

 

Ordered all the goodies. HC-06 and a 10hz GPS. Will update when I get it all soldered up and in an enclosure. Hopefully I can box it in and not have too big of an issue with signal.

 

Im going to use a 3d printed case with a clear acrylic laser cut top to keep the interference down.