3-Digit Odd Counter Using D-FLip Flops IC's, Digital Logic Design Project

In this digital logic design project, I have made a 3-digit odd counter using D-Flip Flops. This counter has features like:

1. User desired input
2. Pause option
3. Reset option

Warning/Note

Note: always use resistors to apply active ground at pins of the ICs which require active low logic or at all the inputs to provide zero. Otherwise, ICs will put out garbage values.

Note: please use a proper 5V power supply that has plenty of juice in it so that all the logic ICs perform as intended. I used a bread board power supply to provide power.

Things required for this project are:

1. D-Flip Flop ICs
2. AND Gate ICs
3. OR Gate ICs
4. NOT Gate ICs
5. 555 timer IC
6. Resistors for generating Clock and for providing active ground
7. Capacitors for generating Clock
8. 4-bit Bit Switches
9. 7-Segment Displays
10. Binary to Seven Segment Decoder ICs
11. BCD Counter ICs
12. Push Button (toggle)
13. ON/OFF slide Button
14. Jumper Wires
15. Bread Boards
16. Bread Board Power Supply

Note: You can use 3-way AND & OR gates, they weren't available for me so i use the 2-input ones.

First of all we will write down all the states for our counter. That is how our odd counter using D-Flip Flops will initiate and continue. To make a 3-digit odd counter we only need to change the 1st digit on ones decimal place to odd number. That is the counter starts from 0 and then goes to 1,3,5,7,9 and then again at 1 not zero i.e. because its an odd counter. Now for the tens and hundreds decimal place we will use simple BCD counter IC to count from 0 to 9, the clock for this IC will come from the odd counter, basically we will cascade 2 BCD counters with the ODD counter.

Now the next step is writing the truth table and logic to make the ODD counter work. We achieved this goal as shown in the picture above. Now we know what the inputs for the D-Flip Flops should be.

In this next step we will use the truth table to write down the Karnaugh map to get the logic gate equations so that we can implement our counter using the ICs. K-map is solved in the picture above.

The best way to check if we have done the above calculation right is to implement this circuit on simulation software, also it's a good practice to check working behavior of our circuit design before moving to hardware. I used Proteus 8 for this purpose. As you can see in the schematic. Once the simulation works, you can go ahead and implement it on a PCB or Bread Board.

Note: always use resistors to apply active ground at pins of the ICs which require active low logic or at all the inputs to provide zero. Otherwise, ICs will put out garbage values.

Note: please use a proper 5V power supply that has plenty of juice in it so that all the logic ICs perform as intended. I used a bread board power supply to provide power.

The simulation file and other data can be found on this GitHub link:

https://github.com/fahadqalbi/3-Digit-ODD-counter-using-D-flip-flop