The LED clock consists of 60 LEDs which are placed circular around a common analog clock. The LEDs are used to display the seconds. Essential part of this circuit is the LED driver MAX7219 from Maxim. A datasheet is available on Maxim s homepage. The clock is controlled by the microcontroller AT89C2051 from Atmel. This microcontroller is clocked at a frequency of 12 MHz from which results a time base of 1 microsecond. Via software dividers one clock impulse per second is generated which is used for updating the LED display.