This particular smart watch by Jonathan Cook won the MAKE challenge this year and it's an interesting application in wearable technology. It's Powered by an ATmega644PA Microduino Core and an ATmega1284P microcontroller (MCU), the device features Bluetooth LE connectivity and a 3D-printed case. Apart from time, there are working on update which will give you Facebook or Twitter notification. It has an OLED screen which might be a little heavy on your wallet, along with vibrational motor and few LED sequins and general electronics.
The clock is Arduino compatible. It uses BLE112 library, Time Library, OLED Library and a Graphic Library all of which are available on the internet. There are two breakouts to allow the Arduino to be programmed via a FTDI friend, and the BLE112 chip to be reprogrammed by a CCDebugger. The battery includes a switch and an extra charging jack. The switch has 2 modes, either on, or charging. The Screen is connected to the microduino via predefined hardware SPI pins, providing the fastest graphical update. A small vibration motor is also there which is connected using a transistor.
Read the worklog here.