So I'm working on Designing a decade counter. I saw a previous post made about this same problem and thanks to Mr. Chips got started headed in the right direction.

So here's where I am at.

Truth table for Decade Counter

D C B A D+ C+ B+ A+ (D+ indicates the next state of D)
0 0 0 0 0 0 0 1
0 0 0 1 0 0 1 0
......
.....
1001- 0000
1010-xxxx
....

Then simplifying the K maps for A+, B+, C+, and D+ you get:

A+=A'
B+=BA' + D'B'A
C+ = CB' + CA' + C'BA
D+ = DA' + CBA

Now it's time to put this into a circuit. I'm not really sure how to even start going about this. Besides the fact that it will require 4 Flipflops. Any help would be greatly appreciated

 

Fed the logic of each into a D flip flop. Works well. Guess I didn't need help. Just had to think a little.

 

Glad we were able to help. Good luck on your studies.

 

Good job on figuring it out and good job of searching the forum to get started on your work.