Читать книгу Digital System Design using FSMs - Peter D. Minns - Страница 15

A finite state machine (FSM) is a digital sequential circuit that can follow a number of predefined states under the control of one or more inputs. Each state is a stable entity that the machine can occupy. It can move from this state to another state under the control of an outside world input.

Figure 1.1 Block diagram of an FSM‐based application.

In Figure 1.1, we see an FSM with three outside world inputs (p, q, and the clock) and three outside world outputs (X, Y, and Z). Note some FSMs have a clock input; those that don’t belong to a type of FSM called ‘asynchronous FSM’. However, this chapter deals with the more usual synchronous FSM, which do have a clock input. Only Chapter 4 and Chapter 6 will look at asynchronous FSM.

Synchronous FSM can move between states only if a clock pulse occurs.

Task: Draw a block diagram for an FSM with five inputs (x, y, z, t, and a clock) and with two outputs (P and Q).

When you have done this, turn to Frame 1.2.