We recently talked about how there really is nothing like the comforting glow of a Nixie tube. But what if you felt like building something that glowed (not necessarily red) and could be carried around in your pocket?
Well, that is exactly what a Maker named Frank did when he wanted a classy (and rather different) way of telling the time by designing an LED pocket watch around Atmel’s ATmega645P. As you can see in the video below, the watch features 132 LEDs for displaying the time, two buttons to activate and change modes, along with a vibration motor and buzzer.
As the folks at Hack A Day note, Atmel’s picoPower ATmega645P controls the LED pocket watch, which is equipped with enough pins to drive the expansive array of LEDs as well as an internal real time clock. The device – housed behind a laser-cut acrylic face – sits in a 3D printed case and sips power from a rechargeable lithium coin cell battery. The charging circuitry is based on an MCP73831, while a USB connector provides power to the board.
“One of the bigger challenges of the design is driving the large array of LEDs,” writes Eric Evenchick of Hack A Day. “[So] Frank uses Charlieplexing to group the LEDs and reduce the number of pins required. Another trick he used was offsetting the ISP header pins. This allows for programming the AVR without soldering a connector to the board.”
Additional details, such as schematics, PCB layout, software design and case plans can be found here on Instructables.