1.2 Methods for Implementing State Machine

There are multiple ways to implement state machines. State machines can be implemented in firmware, hardware, or a combination of both. Each method of implementation has its pros and cons.

To understand the various methods of implementation, let’s refer back to the General State Machine block diagram. There are four aspects to any state machine that need to be implemented:

State of the Machine
Next-State Function
Output Function
State Time

These aspects of a state machine can be implemented using firmware or hardware. The following sections provide a detailed explanation of each implementation method, while Table 1-2 summarizes the differences between them.

Table 1-2. Summary of Firmware and Hardware-based State Machines
State Machine Function	Firmware Implementation	Hardware Implementation
State	Variables	Flip-Flops
Next-State Function	Written code for logic	Discrete logic elements (such as gates and look-up tables
Output Function	Written code for logic	Discrete logic elements (such as gates and look-up tables
State Time	Software or hardware counters	Hardware timer/counters