Multiplex7Seg4Digit is an Arduino library that allows you to display numbers on the 7-segment 4-digit display (12 pins) connected to 2 multiplexors. So you can use only 3 Arduino pins instead of 12 if you connect a display directly to Arduino board.

Known problems and limitations:

• only 1 display;
• only positive decimal values;

Dependencies:

• MsTimer2 library

Components

• 2 x 8-Bit Shift Registers SN74HC595N
• 1 x 7-Segment 4-Digit 12-Pins Display with common Cathode (like 3641BH or analogs)