You are to design a 4-bit BCD up/down counter. Depending upon the value of the up/down bit, the circuit follows one of the two count sequences, respectively. 

0000-0001-0010-0011-0100-0101-0110-0111-1000-1001-000

 Or

 1001-1000-0111-0110-0101-0100-0011-0010-0001-0000-1001

4 bit BCD up counter has been designed 

Step-by-step explanation

Solution "- we are designing 4-bit BCD Up counter - Truth Table : - CLK 93 92 O 0 O D - 2 0 1 3 O 1 4 0 0 0 5 O 1 1 0 7 D - 1 1 0 - 10 0 Termination count Here "10 10" is the count at which we need to clear all the flip- flop , so that Counter again comes back to "oooo"

In this design we will be using 'I' blip - blop which is also know as toggle - flip - flop, whose next state equation is given as Qnti - - On T = QnT + QnT T= 1 then Anti = On =) so when ever a flip-blop gets a negative edge it will toggle 13 Q 1 12 T, To go OD 4 3 Q 2 Q , CLEAR CLER CLER CLER CLK AND

Please see the attached file for truth table