Make Your Own Smart Watch

SmartWatch

Wearables are all the rage lately. Have you been eyeing the Pebble or one of the new smart watches lately but are not sure if it’s for you? With [GodsTale's] “Retro Watch” you can now build your own, allowing you to try out a smart watch without making a huge investment.

This smart watch uses very common and easy to obtain parts: Arduino Pro Mini, HC-06 Bluetooth module, Adafruit’s 0.96’’ OLED display, and a lithium battery. It is amazing how few parts can be used to make such a functional project. While the example packaging shown is a bit rugged around the edges, it gets the job done. Having such simple hardware allows [GodsTale] to focus on the software. One of the coolest aspects of this project is the Android app [GodsTale] provides. The app provides basic functionality, such as viewing RSS feeds and Android notifications. Check out the GitHub and a more detailed write-up for more information.

It would be great to see this project evolve in the future, it has so much potential. We would love to see a custom circuit board, or a model for a 3D printed case for this awesome smart watch. See a video of the Retro Watch in action after the break. If you thought this was cool, check out a few of these recent hacks.

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nrf24l01+ using 3 ATtiny85 pins

attiny85_nrf_2

[Ralph] wasn’t satisfied with the required 5 control pins to drive his nrf24l01+ transceiver module, so he used this circuit needing just 3 pin using an ATtiny85.

One of the key components was to effectively drive the chip select (CSN) line from the clock (SCK) line. The nrf24l01+ needs the CSN line to transition from high to low on the beginning of a communication.  [Ralph] put the SCK line behind a diode, put a capacitor in parallel with the CSN line and altered the arduino-nrf24l01 library to encode extra delays for the clock line.  This allowed the CSN line to be driven by the SCK line. Subsequent line transitions during transmission happen too fast to charge the capacitor, leaving the CSN line in a low state.

After tying the chip enable line high and dropping the 5V power line to 1.9-3.6V across a red LED, [Ralph] had an ATtiny85 controlling a nrf24l01+ module.

Though deceptively simple, a very cool hack that opens up a couple more lines on the ATtiny85.

Generating Embroidery with an Arduino

Arduino Embroidery Generation

Want a nifty way to combine the craft of embroidery with electronics? The folks working on the open source Embroidermodder demoed their software by generating an embroidery of the KDE logo using a TFT screen and an Arduino.

Embroidermodder is an open source tool for generating embroidery patterns. It generates a pattern and a preview rendering of what the embroidery will look like when complete. It’s a cross-platform desktop application with a GUI, but the libembroidery library does the hard work in the background. This library was ported to Arduino to pull off the hack.

While generating pictures of embroidery with an Arduino might look neat, it isn’t too useful. However, since the library has been ported it is possible to use it to control other hardware. With the right hardware, this could be the beginning of an open source embroidery machine.

After the break, check out a video of the pattern being generated.

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An Android Controlled Arduino Drone

Drone

Who among us has not wanted to create their own drone? [Stefan] wrote in to tell us about a project for high school students, where a Styrofoam glider (translated) is converted into an Android (or PC) controlled drone.

[Stefan] tells us that the inspiration for this project comes from 100 years ago, when “steam-engines were THE thing” and children became introduced to modern technology with toy engines. “Today, mechatronic designs are all around us and this is an attempt to build the equivalent of the toy steam engine.” This project showcases how modern tools make it easy for kids to get involved and excited about hardware hacking, electronics, and software.

At the heart of the glider is an Arduino Pro Mini which communicates with either a computer or an Android phone via Bluetooth. It is especially interesting to note that the student’s used Processing to create the Android app, rather than complicating things by using Eclipse and Android Development Tools (ADT). While the more detailed PDF documentation at the end of the project page is in German, all of the Processingand Arduino code needed to build the project is provided. It would be awesome to see more Bluetooth related projects include a simple Android application; after all, many of us carry computers in our pockets these days, so we might as well put them to good use!

Do you have any well documented projects that introduce young and budding engineers to hardware or software hacking? Let us know in the comment section or send us a tip!

A Clock That Plots Time

plotclock

[Johannes] just sent us a tip about his small plotter that plots out the current time.

[Johannes] small clock plotter uses a dry wipe pen to write out the time on a small piece of dry erase board. The design is Made of three small 9g servos, with one to lift the pen off the writing surface and the other two to control a pair of connected jointed arms for the x and y-axis.

The little robot painstakingly wipes away the previous time before scrawling the current time in its place (with minute accuracy).

[Johannes] had hackability in mind when creating this project, making sure to keep to standard parts and making the code and design files available. The hardware for the build can be laser cut or 3D printed. The Arduino sketch can be found on GitHub and the design files can be found on Thingiverse. There are more detailed build instructions on Nuremberg’s FabLab page (translated).  [Read more...]

Arduino Powered ECG Informs Users of Their Death

ekg

Just when you thought you’d seen an Arduino do everything, [birdyberth] built an Arduino powered Electrocardiogram (ECG or EKG). Electrocardiography is a non invasive method of studying the heart. For many of us that means a 10 minute test during our yearly physical exam. Medical grade ECGs can use up to 10 electrodes. To keep things simple [birdyberth] went the route of a few circuits we’ve seen before, and reduced it to two electrodes and a ground reference. [birdyberth] makes note that the circuit is only safe if battery power is used.

The “heart” of any ECG is an instrumentation amplifier. Instrumentation amplifiers can be thought of as super differential amplifiers. They have buffered inputs, low DC offset, low drift, low noise, high open loop gain, and high impedance among other favorable characteristics. The downside is cost. A typical op amp might cost 0.50 USD in single piece quantities. Instrumentation amplifiers, like [birdyberth's] INA128 can cost $8.30 or (much) more each. The extra cost is understandable when one thinks about the signals being measured. The ECG is “picking up” the heart’s electrical signals from the outside on skin. On commonly used ECG graph paper, a 1mm square translates to about .1 mV. High gain and clean signals are really needed to get any meaningful data here.

Electrodes are another important part of an ECG. Medical grade ECG units typically use disposable adhesive electrodes that make a strong electrical connection to the skin, and hurt like heck when they’re ripped off by the nurse. [birdyberth] was able to make electrodes using nothing more than tin foil and paper clips. We think the real trick is in the shower gel he used to make an electrical connection to his skin. While messy, the gel provides a low resistance path for the tiny currents to flow.

The actual processing in [birdyberth's] circuit is easy to follow. The signal from the instrumentation amplifier is sent through a low pass filter, through a 741 op amp, and then on to the Arduino. The Arduino uses a 16×2 LCD to display heart rate in beats per minute, along with a friendly message informing you if you are alive or dead. The circuit even provides audible feedback for heart beats, and the classic “flatline tone” when the users either disconnects the electrodes or expires. [birdyberth] has also plugged in his pocket oscilloscope just after the low pass filter. As his video shows, the familiar ECG waveform is clearly visible. We’d love to see a more complex version of this hack combined with [Addie's] heart simulator, so we could know exactly which heart malady is killing us in real time!

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From vacuum cleaner hacking to weather station reverse engineering

spectrum

[Spock] wanted to do a little reverse engineering of his Miele brand remote control vacuum cleaner, so he broke out his DVB-T SDR dongle to use as a spectrum analyser. Sure enough, he found a 433.83Mhz signal that his vacuum cleaner remote control was using, but to his surprise, he found a stray QAM256 signal when he expected an ASK  only one.

After a little detective work, [Spock] eventually tracked it down to a cheap weather station he had forgotten about. The protocol for the weather station was too compelling for him to go back to his vacuum cleaner, though. After downloading an rc-switch Arduino library and making a quick stop at his local radio shack to get a 433.92 radio receiver to decode the signal, he reverse engineered the weather station so he could digitally record the temperature output. The Arduino rc-switch library proved unable to decode the signal, but some Python work helped him get to the bottom of it.

With software defined radio becoming more accessible and common place, hacks like these are a nice reminder just how wired our houses are becoming.