This clock is built with wsduino (an Arduino compatible board with RTC that I designed), and a dual bi-color LED matrix shield (also designed by me). This basic clock has two buttons, for setting up the hours and the minutes. The RTC is the extremely accurate DS3231, with back up battery to hold the time even when not powered. The wsduino can be re-programmed with your own clock (or other) sketch, using the Arduino IDE. (The current clock sketch that I wrote is open source.)

Here are more details on the wsduino board.

The wsduino board can accept an XBee-footprinted device, like a GPSBee or a WiFiBee, which could make the clock synchronize with either the GPS or an NTP server, respectively. The clock can be customized with other devices like Bluetooth (e.g. display messages sent from your Android device), buzzer (to make it into an alarm clock), relay (to start/stop an appliance) etc,

As mentioned, setting up the time cannot be simpler: press one button to increment the hour, the other button to increment the minute. The display mode is changed by pressing both buttons simultaneously. The 4 display modes are:

• simple HH MM format, military (24 hour) time, all green;

• simple HH MM format, 12 hour time, all yellow;

• HH MM 12-hour format (in green), with red dot moving around the edges to indicate seconds (simulating a second hand on an analog clock);

• HH MM SS 12-hour format, with hours (in red) and minutes (in green) mixed on the left half, seconds (in yellow) on the right half.

More details on the software (video included) can be found here.

The enclosure is made of laser-cut 3mm plexiglass and standoffs. The two buttons are accessible from the top.

The clock is powered with 5V through the USB miniB connector.