Monthly Archives: July 2012

Really Small(s) GPS

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Hi peeps, I have been wanting to make a small GPS device (GPS receiver and some sort of screen) that I could carry around for a while now, but I didn’t want it to be too big, so I made this. Mission accomplished.

This unit is explained in the video above, but is basically a GPS receiver, 1 CR1220 battery for the RTC on the GPS breakout, one of my Square Inch of Goodness boards, one 128×32 OLED display, three 6mm buttons, and a 400mAh Li-Po Battery (from Sparkfun). It even has FTDI headers on it so I can update the firmware with ease (with my own FTDI adapter!). The awesome part is that all of those things fit in an Altoids Smalls tin, measuring 2.15″ (W), 1.35″ (L), and .56″ (H), or 55mm (W), 34mm (L), and 14mm (H).

The GPS breakout board is from Adafruit and uses the MTK3339 GPS module, and man does it work well. I have had other GPS modules that worked, but it was a fight. If you’re thinking about putting GPS in a project, use this. They also have a great library for it. They even have the raw MTK3339 GPS module if you want to use your board. Read the Adafruit product page for all the features, there are many.

The 128×32 OLED display is also from Adafruit, it works well and has the typical OLED crispiness. Very easy to read, even in sunlight, for the size and you can even multiply the text size if you want to.

So I’m going up to NY in a few days, and I wanted a new and exciting way to talk with the TSA folks, so I figured this would work. (kidding) If only Hollywood had not trained everyone to think a gadget with a few wires and a flashing red LED, that they didn’t understand, was a bomb.. ugh. (not kidding)

*UPDATE – there is a set on Flickr for this with teardown pictures.

*UPDATE #2 – Oops, I forgot to put the link to the code on Github. 0_0

Fast Voltage Switching FTDI Adapter

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I have been working more with 3.3 volt projects lately and wanted to make programming them with an FTDI adapter as easy as possible. Sure you can switch most FTDI adapters from 3.3 to 5 volts (the FT232RL chip has a built in 3.3 output as well as logic level selection), but it involves scratching a jumper wire and soldering pads. This isn’t bad to do once, but to go back and forth is time consuming and rough on the boards.

So, I made my own FTDI adapter with an easily changed jumper for voltage selection. I also added a power LED to let me know that it’s plugged in and ready to go, threw in some RX and TX indicator LED’s and all required caps (read the data sheet), and mini USB jack. I ordered the boards from OHSPark.com, and as always, they were great.

Eagle files are on my Github page, or you can grab just the schematic in PDF format here.

Adafruit has an FTDI Friend and Sparkfun has an FTDI Basic if your not up to soldering 28 Pin SSOP packages, or just want one. 🙂

Homemade Flux Remover

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I was inspired by a video by Jeri Ellsworth that showed her using homemade flux remover. This is super simple a combo of alcohol and acetone. In this video, I use a 50/50 combo of the two. So that’s 32 oz. of flux remover for $3. I Googled flux remover and it ranges from $10 to $25 for 12 oz. So that a savings of at least about $70. I have been using this on about every board I can find and it has worked great on all of them. I heart saving money. 🙂

One Square Inch of Goodness

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So a while ago I discovered that I needed a microcontroller in a really tight space. I tried an ATmega328P PU (DIP package), but try as I may, It would not fit. The answer? The ATmega328P AU (TQFP) this is a much smaller package, and for an added bonus, it has 2 extra ADC’s. This a great little board to squeeze in various projects, and opens the door to some very cool stuff I have coming up. Some of you might remember I put this board in a project I did a while ago when space was very limited. It’s just a handy little board to have on hand. 🙂

In the video above, I show some soldering with TQFP packages, as well as a little soldering with hot air. I need to figure out a way to record video from my brain. It would make things so much easier..

Oh, I almost forgot, the flux pen I used, found at Sparkfun.

The Eagle files for this board are on my Github page. Or just the schematic PDF.

Serial or Speed..

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This video above demonstrates the speed difference between serial enabled/disabled on an Arduino Uno while toggling a pin output. Just a really simple test of how fast it can pull a pin high and low (without using direct port manipulation), with and with out serial enabled. I think that was the smallest Arduino sketch I ever wrote..