An ATTiny24 controls all aspects of this device. It scrolls up to 5 unique, 18 byte long messages on its charlieplexed LED matrix display. The display is driven directly by the ATTiny using 7 pins, with no other supporting hardware. It is powered by a 3V coin cell, and uses an average of 8 mA during normal operation, and 5 uA while sleeping. The button is used to switch between displayed messages, and to enable/disable sleep mode.