Easy As Pie GPS Datalogger

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Introduction: Easy As Pie GPS Datalogger

This project came out of a very simple need; the need for speed. The night before I was leaving on my road-trip across the Grand Canyon, I realized I didn't have my Garmin with me. So I hacked this together. However, I have since realized I absolutely love the simplicity of this thing. There's a certain freedom in just pushing a button, being sure that your tracks will be recorded and dealing with everything else later on.

I know what you're thinking. Isn't there an app for that? Well, my three part answer to that is that apps crash, phones die and A-GPS(the kind of GPS used in phones) doesn't work everywhere. I learned this lesson the hard way.

The idea is pretty simple. I have two main components, a GPS unit that sends the current GPS location over serial and Openlog from Sparkfun which takes a any incoming serial data and writes it to a microSD card. To access the data, just pop the microSD card into your computer and open the file using Google Earth. Easy as pie!

Step 1: Get Set!

Here's what you need:
* OpenLog datalogger
The easiest way to log serial data!!
* GPS unit
Selected for it's small size
* AA battery holder
* AA Batteries
* Slide switch
* microSD card formatted to FAT16/32 (not in picture)

Step 2: Make It!

There really isn't much to describe. I removed the 4 pin connector as it was taking too much space. Then, using some jumper cable I soldered the following connections:

GPS OpenLog Battery
+V------------------------+V--------------------------+V
Gnd---------------------Gnd-----via switch-----Gnd
Tx------------------------Rx

I drizzled entirely too much hot glue over everything to make sure it was (slightly) water resistant.

That's it! Put a formatted SD card in OpenLog, flick the switch and you're in action. Switch it off and there's no battery drain. Every time you switch it on, OpenLog creates a new file in the misroSD card, storing all the data the GPS is sending.

Step 3: Use It!

When you first switch on the unit, you will note that a blue LED blinks on the OpenLog, this indicates that the unit is functional and recording data. If it stops biking, it's time to replace the batteries. I measured the current draw to be 55mA on average. With a 2000mAh AA battery, that would be just over 36 hours of continuous use.

When you first switch on the GPS it can take a solid 15-20 minutes to get a fix on the location. I would suggest powering on the GPS and leaving it outdoors for an hour the first time you use it. Then verify that you did indeed get a fix on your location. After this, as you use it normally, it would get a fix within 10-15 seconds.

The logs are stored as numbered .txt files "LOG00001.txt", "LOG00002.txt" so on. But the data is actually in NMEA format. So, to open the data in Google Earth you have to rename the file to ".nema". So "LOG00001.txt" becomes "LOG00001.nmea". You can then open it in Google Earth by just going to File>Open and browsing to the file.

You can get creative with it and use tools like MapBox to make some amazing roadtrip scrapbooks!

2 People Made This Project!

  • MikeD279 made it!

  • Crucio made it!

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40 Comments

Hi! I built it and have a .TXT file that I renamed .NMEA but Google Earth doesn't recognize it as a GPS file. I can't even select it from the "open" drop down...

Any idea?

Thank you for the fun project BTW!

Actually, that's not necessary. If you do the TXT -> nmea rename, there's a dropdown to open nmea data in the open dialog of Google Earth. I just did that and it worked without problems.

Currently only breadboarded, but I used a tiny $16 SparkFun GP-20U7 GPS, a 3.3v regulator, 3xD cell batteries, a switch, and of course the openlog. Works great! Planning to take it on a long sailing trip next year. Thanks again, tinkrmind!

Found a smaller GPS. it works well!

So glad you got it working! Thanks for sharing!!

I want to make a smaller version of this, powered by a single AA battery. I also want the GPS antenna to facing upwards when I have it in my pocket, but I am having problems finding a suitable GPS receiver. I want an antenna such as this one: http://tinyurl.com/h5f74e9 but the receiver board is too large.

Can anyone recommend a smaller receiver? The antenna needs to be small enough to be placed along the shortest edge of the case.

If you want to power it off of a single AA battery, you'll need a DC-DC converter. That will decrease the efficiency quite a bit as well.. But here's the smallest GPS module I could find. Here's a small 5V step up module as well.

thank you. I am actually now looking into making my own pcb with all the neccesary components embedded. Why do you say that a voltage regulator/booster will make the system less efficient? I only need to provide 3.3V, which limits the gap between Vin and Vout. I bet I could find a regulator that does that pretty efficiently. In addition, some boosters can operate with voltages as low as as Vin=0.5V, making it possible to extract more power from the battery than without a booster. Overall, the power supply could be more efficient with a regulator than without.

I only meant to point out the losses in DC-DC conversion, which would be significant if, say, you took an off the shelf converter module-those things get hot!. But hey, if you're spinning your own board, nothing is stopping you! I'm sure you can convert 0.5-1.5V to 3.3V with >90% efficiency. And
you might be able to get the last 10-20% juice from the battery when it
goes below 1V. So there's a marginal gain in power there. But can decrease the power consumption further by moving to say an attiny instead of the Atmega328 and using the lowpower library cleverly. Go for it man! Looking forward to the results :D