Читать книгу Digital System Design using FSMs - Peter D. Minns - Страница 16

The FSM with five inputs (x, y, z, t, and a clock) and two outputs (P and Q) is shown in Figure 1.2.

If you did not get this answer, go back and re‐read Frame 1.1. Don’t worry about using a mixture of both upper‐ and lower‐case letters here; the only thing that matters is that the same letters are used.

Each state of the FSM needs to be identifiable. This is achieved by using a number of internal flip‐flops within the FSM block. An FSM with four states would require two flip‐flops since two flip‐flops can store 2² = 4 state numbers.

Figure 1.2 Block diagram with five inputs and two outputs.

Each state has a unique state number, and states are usually assigned numbers, such as s0 (state 0), s1, s2, and s3 (for a four‐state example).

As you can see, the rule here is 2^{number of flip‐flops}.

So an FSM with 13 states would require 2⁴ flip‐flops (i.e. 15 states of which 13 are used in the FSM and states 14 and 15 remain unused.

How many flip‐flops would be required for an FSM using 34 states?

What would the state numbers be for this FSM?

When you have answered these questions, turn to Frame 1.3.