I've been trying to make a timer that starts from 0 then counts down at 9 to 0. I've been struggling to make it, i made state tables and diagrams and for the flipflops but when implementing to a simulator it just doesn't give me the output i want.

I've tried making the don't cares (10-15) as 0 but still doesn't work.

Heres the state diagram:
[![enter image description here][1]][1]

Heres the state table
[![enter image description here][2]][2]


I followed the kmap results in the simulator but still can't get it to work.

  [1]: https://i.sstatic.net/ejU77.jpg
  [2]: https://i.sstatic.net/gCmFG.jpg