DS-FND-BSX-PC Xilinx Inc, DS-FND-BSX-PC Datasheet - Page 182

• Manufacturer Part Number: DS-FND-BSX-PC
• Description: FOUNDATION BASE SYS W/SYN EXPRES
• Manufacturer: Xilinx Inc
• Type: Foundation Systemr

Specifications of DS-FND-BSX-PC

• For Use With/related Products: Xilinx Programmable Logic Devices
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant
• Other names: 122-1185

Foundation Series 2.1i User Guide
Encoding Techniques
7-4
Symbolic and Encoded State Machines
Figure 7-2 Parts of a State Machine
The amount of logic used to calculate the next state varies according
to the type of state machine you are implementing. You must choose
the most efficient design approach, depending on the hardware in
which the design will be implemented.
The states in a state machine are represented by setting certain values
in the set of state registers. This process is called state assignment or
state encoding.
There are many ways to arrange, or encode, state machines. For
example, for a state machine of five states, you can use three flip-flops
set to values for states 000, 001, 010, 011, 100, which results in a highly
encoded state machine implementation. You can also use five flip-
flops set to values 00001, 00010, 00100, 01000, 10000, that is, one flip-
flop per state, which results in a one-hot-encoded state machine
implementation. State encoding has a substantial influence on the
size and performance of the final state machine implementation.
A symbolic state machine makes no reference to the actual values
stored in the state register for the different states in the state table.
Therefore, the software determines what these values should be; it
can implement the most efficient scheme for the architecture being
targeted or for the size of the machine being produced.
Inputs
Logic Gates
Feedback
Registers
State
Logic Gates
Outputs
Xilinx Development System
Outputs
X4635