MatrixClock

Building it up

Setting time

Arduino sketch

What I did

LEDs are cool and so are grids! I bought an 8x8 red LED matrix online a while ago and determined to make a clock with it. 

The challenge was to come up with a way of displaying the time with so few pixels. I use the outer LEDs to show the minutes (to the nearest 5) and I designed a 4x4 pixel "font" to show the hour on the inner LEDs. 3:50 is shown on the left (3 in the middle, 3 quarters + 5 minutes). 
Having played with accelerometers in my SleepyTimer project I decided to use them here too: the clock has no buttons. The various display modes are selected based on orientation.
Changes in the orientation are used to set the time.

There are more photos, videos and details on flickr.

Demo mode

Display modes