000 to 999 Display in Quad 7-Segment Display with AVR ATmega16 Microcontroller

In this project, we will learn How to display from 0000 to 9999 in four common anode 7-segment displays with AVR ATmega16 microcontroller. The four 7-segments are connected to the AVR ATmega16 microcontroller using multiplexing technology to save 20 I/O pins of AVR ATmega16 microcontroller. For detail see the circuit diagram. The microcontroller selects one 7-segment at a time to display one digit of the four digit number. But, the speed at which the microcontroller selects the 7-segment to display the digits is very fast. At this speed, the human eye cannot detect that; at any instant of time only one 7-segment is displaying one digit of the number and the other 7-segments are not displaying anything. The microcontroller displays the numbers from 0000 to 9999 in the four 7-segment displays and the microcontroller uses its compare match interrupt of Timer Counter feature to give a time delay between two consecutive numbers (delay functions cannot be used to give time delay between two consecutive numbers).. When the display reaches 9999, it will restart the display from 0000 and the above process continues forever.