Sub $50 10Hz GPS Receiver
 

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)

http://i62.tinypic.com/2yv9mon.jpg

http://i59.tinypic.com/23jnxog.jpg

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.

Not to be a dick, and it's a little more than $50, but have been available for ages (Qstarz BT-Q818XT). But that includes a more cave-man-proof concept.
The sensitivity of the antenna and more importantly the processing of the data will give different results when it comes to positioning and mounting.
I never had a problem with a Qstarz unit duck-taped to the cage (even on the A-pillar tube, with the A-pillar and the glass in the way), when using Racechrono. The frequency makes the positioning on track good enough (it's always better when you have some extra satellites and crisper data of course).

That RT DL1 have problems when there is any minor flaw in the data falls in their way of working, fix the sensors, and let the unit/software show the sensor data as-is (even create some smoke when the input voltage is off). Filtering and protection is for sissies.

Was hoping for a $50 10Hz subwoofer...

Got a couple of these in the mail today. Need to do some testing to see how much power it will consume.

http://i57.tinypic.com/etwoap.jpg

Case will be designed similar to this.

https://www.miataturbo.net/attachmen...ine=1423760093

Got my second chip in the mail today. I like this one better. Cheaper, larger antenna, simpler connections.

I took it outside to get a fix and once it had it I was able to go back in my house and keep the fix. I need to take it for a drive still but good so far.

http://i61.tinypic.com/33y029d.jpg

Updates, got everything connected, currently designing a case. Testing will happen today or tomorrow:

http://i58.tinypic.com/10e0e9v.jpg

http://i58.tinypic.com/97jsiq.jpg

http://i58.tinypic.com/j7fgix.jpg

I am excite!

I've seen that one. But cost of materials right now is 25 dollars. Which is almost a 4th of the cost of the Qstarz one.

I so want one of these. A comparison between RaceChrono with built-in GPS (Galaxy Nexus) vs transponder at Hallett showed times anywhere from dead accurate to somewhere around a second off. Not exactly a reliable means of measurement. These times are from my 3rd, and final, session of Friday at Miatas@Hallett. That last lap was the death of my poor little IHI.

Sounds about right, the gps on your phone only polls once per second (1Hz).

Case printed and cut:

Attachment 234392

I zee
1 bluethoot module
1 GPS module
1 mini USB for power suply

Is that all?
No extra arduino to translate the GPS code because the output trok GPS is what Android neer
Only set the baut and code of the bluethoot module and your good to go?

So the chip that Schuyler linked doesn't have flash memory so the 10hz setting doesn't stick. Because of this I switched to a different chip that has flash, but that won't be here for another couple weeks.

D: I already ordered it. #YOLO. It gets an atmeta chip to program it errytime I guess.

EDIT: it's 3am and i'm cramming for a test, but I went and got a double 1/4 pounder with cheese and I think something of that magnitude deserves a break. Look through the manual at the Electrical Programmable Fuse (eFUSE). My understanding is you set it up the way you want it, send the binary code, and it burns the current settings to the chip. One time use, hence the "fuse" part. Worth looking in to. http://www.reyax.com/Module/GPS/RYN25AI/RYN25AI.pdf

Already did. eFuse is cant set the refresh rate, only the baud rate. I even confirmed with the manufacturer.

Good luck in your test. The flash chip is only 18 dollars btw.

These GPS modules output serial (as well as i2c), so you dont need anything else. Youre just transmitting serial over bluetooth.

this tread now becomes more intresting
thanks for the reply Tom

Just got off the phone with ublox, and there is definitely no way to set navigation rate in eFuse. Oh well.

Meh I'll cost me $2 to add an ATMEGA328 chip to it, just more work. I think I have 4-5 them somewhere, so I'll probably just do that since I already have the chip. Props (but I'm mobile and don't know how) for digging in to that though, good to know.

I have the command for changing the rate somewhere written down too, but its pretty simple. I'm buying the flash chip just for science. Funny how this has cost me more than the Qstarz module.

R&D isnt cheap, and your time too...

at least you got some back braces out of the deal lol

Very true. I am picking up some suction cups this morning and designing a way to mount this to the windshield, or zipties. It will most likely have a replaceable bottom for however you want to mount it.

self adhesive hook and loop. thats how i mount my Q818XT where ever i want on the car

That would work too, but I have unlimited access to a laser cutter, so this is gonna get fancy.

Sean yours will be ready as soon as the new chip with flash memory comes in. After that I will probably post up a for sale ad. The rules at my work are if I make cash off the 3d printing I have to pay for it, but if its for friends then its free. So I can sell all the parts separate at cost, and if you want it assembled it will be a few extra bucks of my time.

like i said im in no hurry. i have the qstar, this one will just be for toying around with, and i was going to see if i could integrate it with another droid app for my dirt bike expeditions, hard wired into the headlamp circuit. i can assemble it myself, just give me a clue on what to do.

edit- now that im thinking about it, hook and loop probably wont hold on my bike, so a solid mount is a good option. ill probably machine a handlebar mount for it.

Eh, yours is already assembled lol. I just need to test the new chip. I posted some pictures earlier, but the chips are just stacked up in a way that fits perfectly inside the case.

What's the latest on this project?

Any links to recommended hardware to replicate this?

Waiting for another gps chip to come in. Eta another 2 weeks. Then I will have a writeup, cad files, and a little group buy.

Sounds good. I'll probably be in for the group buy :bigtu:

Lol I glued a harbor freight magnet to the battery door.

I will probably have magnet, zip tie, and suction cup mounting. With switchable faces.

I'd love to try to build one, but will get in on the group buy as well. Damn man, thanks for doing all this :bigtu:

They are honestly really easy to put together. Group buy will just be parts+shipping+a little for my time to put them together/3d print stuff. I don't plan on getting rich off this. All files will be open sourced too if you have your own 3d printer and whatnot.

I would be interested in one for sure.

I'll take one.

So because I'm lazy and don't want to have this 10hz gps laying around, I bought a $2.50 arduino nano to set the gps to 10hz on boot up.

Nano V3 0 ATMEGA328P Improve Controller Board Xtwduino USB Driver for Arduino | eBay

That should work, right?

Yeah, make sure that you only have the TX line on the GPS connected to the Bluetooth, and the RX to the arduino. Otherwise you will get errors with the serial data. It will make it impossible to program the GPS chip over bluetooth but will allow you to program with the arduino and read from the bluetooth chip. I personally am firmly anti arduino, so I would have used something else but either way it should work.

You also have to find the string to send that programs the GPS. I can look that up sometime but my board is at work right now.

Holy hell China can make some damn cheap clones.

Why anti Arduino? I'm not an EE/CS guy so that's just about the only think I can program by stealing a bunch of code snipts from all over the interwebs.