Synchronous Counter to go through sequence 1,2,5,6,3,4,7,0
If your teacher asked to design this with only D flip flop , I don't know is it possible of not, But using 3 D flip flop and a 2 half adder (or 1 full adder) , you can easily design it. if you look closely , your LSB bit ( "C" ) just flipped in every clock cycle and AB is just the value of "AB+C" bits. 







simulate this circuit &ndash; Schematic created using CircuitLab