wearable

Sound Sensitive Earrings

I made these sound sensitive earrings as something blinky to wear while volunteering at the New York City Girls Computer Science and Engineering Conference. These earrings are a fun example of something interesting you can make with some basic computer science and electronics skills. This project is a mash-up of two Adafruit projects: the Gemma hoop earrings and the LED Ampli-Tie. They can easily be assembled in a few hours.

To start, you will need two Gemma microcontrollers, two NeoPixel 16 pixel rings,  two microphones, two small rechargeable batteries, some wire, some jewelry findings, double stick tape, electrical tape and soldering tools. Make sure that you also have a charger for the rechargeable batteries. It’s also a good idea to paint the front of the microphone board black so that it blends in better with the electronics.

earrings_soldered

These earrings are assembled similarly to the Gemma hoop earrings with the additional step of attaching the microphone. First, start by attaching the LED ring to the Gemma. Connect the IN pin on the LED ring to the Gemma’s D0 pin and connect the LED ring’s V+ and G pins to their respective 3Vo and Gnd pins on the Gemma. Next, attach the microphone. It’s a good idea to place black electrical tape on the back of the microphone board before assembly to help prevent any shorts. Connect the microphone’s OUT pin to the Gemma’s D2 pin and connect the microphone’s VCC and GND pins to their respective 3Vo and Gnd pins on the Gemma. Be sure to run the microphone’s GND wire under the microphone so that the wire is concealed. Solder everything in place.Once the earrings are soldered together, it’s time to program them! I used a modified version of the Ampli-Tie sketch (available on the Adafruit site). I made a few minor modifications, such as changing the pins, removing the tracer dot, and adding a reverse mode so that the earrings can light up in opposite directions.

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Next, attach the battery to the back of the Gemma with double stick tape. I also used a permanent marker to color the red battery wires black. Black electrical tape can be used to secure the battery and battery wires to the back of the LED ring and microcontroller.

Finally, attach the earring hooks to the LED ring. I simply attached small O-rings to the OUT pin of the LED ring and then attached the earring hooks with another small O-ring. And that’s it – turn on the Gemma and you are good to go! I found that my 150 mAh battery lasts for about four hours 🙂

Pulse Jacket

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This was one of my first Arduino projects. After some near misses with bicyclists while running at night, I decided to get some lights so people could see me in the dark. But why stop at boring plain lights? Wouldn’t it be cool if they could respond to my heart rate?

I looked at a number of existing heart rate sensors for Arduino, but most were optical and could not get accurate readings while I was running since they were constantly being jarred. Since I run with a Garmin GPS watch and heart rate monitor, I tried to hack into the information being sent between the heart rate monitor and the Garmin watch.

Reading a bit more about the technology, I learned that Garmin used the ANT protocol for communication between the watch and heart rate band. The good news was that SparkFun made an ANT transceiver breakout board. The bad news was that the board was discontinued and I could only get my hands on one board. I decided to move forward with this board for prototyping knowing that I would need to come up with a different solution when I made the final project.

The first step was to get the Garmin heart rate monitor and an Arduino communicating with each other. The ANT protocol documents are pretty thorough and they make great bedtime reading. Fortunately for those of us who are impatient, this thread on the SparkFun forums has sample code that already implements the protocol for the Garmin heart rate monitor.

Microcontroller with ANT breakout board

Now that I had the pulse rate information, it was time to add lights. I am a huge fan of Adafruit’s LED strips. These strips have weatherproofing so it would be possible to run outside in the rain. I trimmed the strips to the length of my arms and sealed the ends.

Microcontroller with lights

I added seven different light modes which increased in speed with the heart rate: rainbow, raindrop, range pulse, color shot, twinkle, circulatory and Cylon. Most of these modes are self-explanatory. The range pulse mode faded the strips in time with the pulse and also chose the color based on the current pulse rate (blue being low pulse, red being high). Here you can see a quick demo of the seven modes:

I then began building the final version. For this, I chose to use a Teensy 2.0 because of its low price and small size. I also had to revisit the ANT transceiver. Searching around, I found this ANTAP281M5IB  module with an on-board antenna. After some very delicate wiring and soldering, this proved to be a direct replacement for the SparkFun board.

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Once everything was working, it was time to put this into a portable package for running. The main concern was power. After a bit of research, I found these Energizer power packs that I could plug directly into the Teensy. The one amp power pack would power both LED strips for about an hour. After verifying that everything still worked, I placed the assembled project into a small project box.

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The last issue was how to attach the LED strips to my arms. I thought about embedding them into a jacket by sewing them in, but I decided against that as it would be a pain to clean. Finally, I just glued some cable clips to the back of the LED strips and used velcro straps to adjust them for the right fit.

Assembling the arm supports
Assembled Jacket

And after all that we were ready to go! My first real-world test was the Midnight Run in Central Park on New Years Eve 2013.

New Years Eve - 2013
New Years Eve - 2013

And now I can easily be seen in the dark!

Microcontrollers!

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Looking through some of my electronics stuff, I realized that I ten different kinds of microcontrollers! That’s not bad at all, considering that I only discovered my love of them last summer. There are five flavors of Arduino: Uno, Uno Ethernet, MEGA, MEGA ADK and Due. There are three flavors of Teensy: Teensy 2.0, Teensy++ 2.0 and Teensy 3.0. There are also two wearables: Lilypad Arduino and Adafruit Flora. So many microcontrollers, so little time!