7. Combinational Logic - Date_of_Birth Circuit

Project Description: Design a combinational logic circuit that has three inputs and seven outputs. When inputs (X,Y, and Z) create a count from 000 to 111, the seven outputs (a through g) generate the logic required to display your date of birth on a seven segment display.

Procedure: In this project we had to use our previous knowledge on Seven Segment Displays to create a combination of inputs that will allow us to display our birthdate. This specific assignment used a common cathode SSD which means that the SSD itself is connected to ground, and for each of the segments to be on, the logic expression must give an output of 1. I first started by creating a truth table, or a table listing all values for each component, which allowed me to plan out my project by giving me the outputs I needed for the circuit to work. After getting values for each component, I made a k-map which allowed me to group up outputs and create a simplified logic expression for each of the components (a,b,c,d,e,f,g). Using these equations that I derived, I was able to create logic circuits for each component on Multisim. We had to make one circuit with only NOR gates and one with only NAND gates, the rest can just be normal AOI circuits (AND, OR, Inverter gates). This part of the project took the most time since I had to make sure each component matched the outputs I derived from my logic expression. After I was done, I ran my circuit for the first time. The inputs were changed 8 times (from 000 to 111) so that each character of my date of birth would be displayed in the form mm/dd/yy. This project has significantly improved my understanding of SSDs and combinational logic.

Video of my circuit: