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State Diagram, State table, State assignment, Excitation table and maps
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written 2.2 years ago by |
mod-6 synchronous counter using T f/f
mod - 6 counter has 6 states.
Hence, the number of f/f's is,
$2^n \gt N \gt 2^n-1$
$\therefore 2^3 \gt 6$
$\therefore$ Number of flip-flops required = 3
Step 1: State Diagram.
Step 2: State table.
present state (Ps) | Next state (Ns) |
---|---|
a | b |
b | c |
c | d |
d | e |
e | f |
f | a |
Step 3: State assignment.
a = 000, b = 001, c = 010, d = 011, e = 100, f = 101.
Step 4: Excitation table of Tf/f and truth table of T f/f
Truth table.
T | $Q_n+1$ |
---|---|
0 | $Q_n$ |
1 | $Q_n$ |
Excitation table.
$Q_n$ | $Q_n+1$ | T |
---|---|---|
0 | 0 | 0 |
0 | 1 | 1 |
1 | 0 | 1 |
1 | 1 | 0 |
Step 5: Excitation table and maps.
| Present state (Ps) | Next state (Ns) | Excitation inputs | |----|----|----|
q2 | q1 | q0 | Q2 | Q1 | Q0 | T2 | T1 | T0 |
---|---|---|---|---|---|---|---|---|
0 | 0 | 0 | 0 | 0 | 1 | 0 | 0 | 1 |
0 | 0 | 1 | 0 | 1 | 0 | 0 | 1 | 1 |
0 | 1 | 0 | 0 | 1 | 1 | 0 | 0 | 1 |
0 | 1 | 1 | 1 | 0 | 0 | 1 | 1 | 1 |
1 | 0 | 0 | 1 | 0 | 1 | 0 | 0 | 1 |
1 | 0 | 1 | 0 | 0 | 0 | 1 | 0 | 1 |
1 | 1 | 0 | x | x | x | x | x | x |
1 | 1 | 1 | x | x | x | x | x | x |
Step 6: Simplifying logic expressions.
$T_2 = q_1 q_0 + q_2 q_0$
$T_1 = q_2 q_0$
$\therefore T_o = 1$