Finite State Machine

Ports:

Port Name	Type	Usage	Description	Comments
Data	I	Required	Data input	Vector, LPM_WidthIn wide
Clock	I	Required	Clock for State transitions	Positive edge triggered
State	O	Optional	Current State Vector	Vector, LPM_WidthS wide. Note 1
Result	O	Required	Result of Logic Function	Vector, LPM_WidthOut wide. Note 2
Aset	I	Optional	Asynchronous set control	Note 3
TestEnab	I	Note 4	Test clock enable input
TestIn	I	Note 4	Serial test data input
TestOut	O	Note 4	Serial test data output	TestOut = StateLPM_WidthS-1

Note 1: The state vector is always present inside the FSM. It may be brought out if needed elsewhere in the design by using the State port.

Note 2: The Result vectors are asynchronous. The outputs may be purely a function of the internal state vector (a Moore machine) or may be a function of both the internal state vector and the Data inputs (a Mealy machine).

Note 3: Aset will set the count to the value of LPM_Avalue, if that value is present. If no LPM_Avalue is specified, then Aset will set the count to all ones. Aset affects the outputs (Result and State ) values before the application of polarity to the ports.

Note 4: Either all of the Test ports must be connected or none of them.

Properties:

Property	Usage	Value	Comments
LPM_WidthIn	Required	LPM Value > 0	Width of input vector
LPM_WidthOut	Required	LPM Value > 0	Width of output vector
LPM_WidthS	Optional	LPM Value > 0	Width of the State vector
LPM_File	Required	String File Name	Name of file containing Truth Table file.
LPM_Pvalue	Optional	LPM Value	Power-up value of State Vector
LPM_Avalue	Optional	LPM Value	Value of State Vector when Aset is asserted.
LPM_TruthType	Optional	F | FD | FR | FDR	Default is FD

Functions:

Result = f(State)	Moore machine
Result = f(State, Data)	Mealy machine
StateT+1 = f(StateT, Data)

Example:

The file FSM1.txt contains:

.start	Kiss
.I 4
.o 3
.p 5
1 ­ ­ ­	dc	idle	1 1 ­
0 1 ­ ­	idle	reading	1 0 ­
0 0 1 ­	idle	writing	0 1 ­
0 ­ ­ 1	reading	idle	1 1 ­
0 ­ ­ 1	writing	idle	1 1 ­
.code	dc	­ ­
.code	idle	0 0
.code	reading	0 1
.code	writing	1 0

This can be better understood by considering the ninth line form the FSM1.txt file:

0 ­ ­ 1	reading	idle	1 1 ­
Data (input)	From state	To state	Result (Output)

Although all LPM_FSMs have a valid state encoding, the fitter is free to re-encode the states. Care must be taken in re-encoding if the state is brought outside the LPM_FSM.