System Description (SR)

The three shift registers are used as the column control unit. Connecting the serial in port to the serial out port of the previous shift register. The three 8 bit shift registers combine to make a 24 bit serial in parallel out shift register. The first in the series has the serial input connected to the micro controller.

To send in bits serially, one bit is shifted in at each clock pulse. Each of the 24 parallel out pins provide a HIGH or LOW to the corresponding LED column depending on the series of bits.