We need 3 flip-flops to hold the current state of the counter QB Qc A+1 QB+1 QC+1 DA DB Dc 0 0 0 0 1 ? ? ? 0 1 1 0 ? ? ? 1 0 1 1 ? ? ? 1 1 0 0 ? 0 0 0 1 ? 0 1 1 0 1 0 0 0 1 1 X X QA 0 MIDDLE TENNESSEE STATE UNIVERSITY, 0 0 0 1 1 1 Extra credit 2: Mod 7 Counter using D flip-flop 1 0 0 1 1 1 0 X ? ? ? ? ? ? ? ? ? ? ? ? ? 101 110 100 C D 0 X 1 0 000 1 1 Q(t+1) Q(t) (no change) 0 (reset to 0) 1 (set to 1) D flip-flop excitation table Steps: 1. Generate the truth table using the excitation table of D flip-flop. 2. Figure out Boolean expressions input D in each D flip-flop (use Kmaps). 3. Draw the circuit diagram. 011 001 010 I AM true BLUE We need 3 flip-flops to hold the current state of the counter QB Qc A+1 QB+1 QC+1 DA DB Dc 0 0 0 0 1 ? ? ? 0 1 1 0 ? ? ? 1 0 1 1 ? ? ? 1 1 0 0 ? 0 0 0 1 ? 0 1 1 0 1 0 0 0 1 1 X X QA 0 MIDDLE TENNESSEE STATE UNIVERSITY, 0 0 0 1 1 1 Extra credit 2: Mod 7 Counter using D flip-flop 1 0 0 1 1 1 0 X ? ? ? ? ? ? ? ? ? ? ? ? ? 101 110 100 C D 0 X 1 0 000 1 1 Q(t+1) Q(t) (no change) 0 (reset to 0) 1 (set to 1) D flip-flop excitation table Steps: 1. Generate the truth table using the excitation table of D flip-flop. 2. Figure out Boolean expressions input D in each D flip-flop (use Kmaps). 3. Draw the circuit diagram. 011 001 010 I AM true BLUE