GPS Data Logging Continued
Once the code is finished uploading, you should see the LED on the TinyDuino blink once every second. This is an indication that the TinyShield GPS is doing its job and polling its location every second and writing that point to the microSD card. Now is the time to venture out into the world and capture some data. Do this by unplugging the GPS Data Logger stack from your PC and powering up the board by a CR2023, JST connected battery, or via the TinyShield USB & ICP like I have done. If you placed the TinyShield USB & ISP board on top of the stack, you will need to remove it now to ensure that the GPS antenna gets a strong signal. If you need this board to power your stack, then move it to a position between the TinyDuino and TinyShield GPS.
When you are finished recording data, head to your nearest PC and open the SD card to view the files stored inside. If you correctly formatted the SD card, then you should only see one file that is titled gps.txt. Make sure you have extensions visible if using Windows, and then rename the file to gps.nmea. The current SD library can only write extensions up to three characters in length and is why the file is saved as a .txt instead of nmea.
Once you have the file renamed, open Google Earth and navigate to Tools>GPS and click GPS. There will be an option to upload a gps file. You can simply browse to the gps.nmea file you renamed, upload that file, and Google Earth will plot the exact path that your GPS Logger took when it was gathering data. There are several other programs that can be used to visualize this data, but I will not list them here as a simple Google Search will give you pages of information on them.
Now that we have the GPS Data Logger working, we need to secure the stack together using the TinyDuino Mounting Kit. This will ensure that the stack stays securely connected during any impacts that might occur during flight.
With everything secure, we also need to enclose the stack inside the case so that it is safe from static discharges, moisture, and debris. You can head over to Thingiverse or Github to download the custom enclosure I designed to house this project.
It is designed to be affixed to a quad-copter or any other half-inch surface using nothing but Velcro straps that are commonly used to bind computer cables together. It could also be secured using zipties as well.
I know that not everyone will have a 3D Printer on hand, and this enclosure could easily be built out of foam board or card board or even polymer clay. For those who do have the option of 3D Printing the enclosure, here is how it works.
The GPS Data Logger fits slightly loose inside the case I printed, and to stop it from rattling around, I used a piece of foam mounting tape to add some pressure. Just a single piece of tape is enough.
Place the tape in the center of the lid and firmly press it into the 3D printed surface. This will ensure a strong bond between the tape's adhesive and the plastic lid.
Now place one end of the lid into the top opening of the enclosure. I designed this case to secure its lid via a friction fit. With the lid aligned correctly, press down and snap the lid onto the enclosure's top.
With everything buttoned up, now would be a good time to use an extra piece of clear tape or electrical tape to add additional protection to the lid. I do not think it will come loose during flight, but it's always better to be safe than sorry, especially when dealing with $100 worth of electronics that is the same size as a quarter.
Now thread some common Velcro PC Cable Ties through the holes in the mounting tabs and secure it to one of the copter's wooden dowel arms. That will finish up this installment of Project M.A.R.V. Next time, we will tackle building the copter's frame and readying things for the electronics. Stay tuned to TweakTown for more awesome Maker and DIY guides just like this one.
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