4-bit synchronous BCD up/down counter

[mehak]

sir i am making 4 bit BCD counter using D-flip flops for this i need just equations when x=1 and when x=0.. plz tell me is this rite or wrong???.... plz............
my sequnce is tha (D3), (D2) ,(D1), (D0) and flipflop inputs are shown as D4,D3,D2,D1. And outputs are D,C,B,A.
x=0,
D4=A'D+ABC
D3=B'C+A'C+ABC'
D2=A'B+AB'C'
D1=A'

x=1,
D4=B'C'D'
D3=B'C+C'B
D2=B
D1=A'

plz rpl me fast i have to submitt it tomorrow plz

 

[mehak]

plz help me plz... give me the state diagram and state table with characterstic table..... plz help me plz

 

[Grossel]

Hi.

I cannot see what the logic you provided above have to do with the working of a counter

It looks to me like you've provided a solution that has nothing to do with the original problem.

 

[mehak]

i just want to know that is this my working is right or wrong??

 

[mehak]

present state next state:
SRQP x=0 x=1
0000 0001 1001
0001 0010 1000
0010 0011 0111
0011 0100 0110
0100 0101 0101
0101 0110 0100
0110 0111 0011
0111 1000 0010
1000 1001 0001
1001 0000 0000

 

[mehak]

flip flop inputs

x=0 x=1
D4 D3 D2 D1 D4 D3 D2 D1
0 0 0 1 1 0 0 1
0 0 1 0 1 0 0 0
0 0 1 1 0 1 1 1
0 1 0 0 0 1 1 0
0 1 0 1 0 1 0 1
0 1 1 0 0 1 0 0
0 1 1 1 0 0 1 1
1 0 0 0 0 0 1 0
1 0 0 1 0 0 0 1
0 0 0 0 0 0 0 0

 

[mehak]

now what should be the equation??