eda lab. dept. of computer engineering c. n. u. 1 fsm structures mealy, moore and combined...

EDA Lab. Dept. of Computer Engineering EDA Lab. Dept. of Computer Engineering C. N. U.C. N. U.

FSM Structures

• Mealy, Moore and Combined Mealy/Moore outputs

• Figure 8.3

Bad FSM Model

• State Diagram

VHDL Code

Cont’d

Problems of FSM1 – BAD

1. no reset, no next state value defined for the unused state.– 2bits FFs: 3 states used, one unused state.

2. Read and Write output assignment infer extra two FFs.– To avoid extra FFs, use separate combinational process.

3. variable initialization– Ignored by the synthesis tools.

FSM1_GOOD

Synthesized Circuit

• State Diagram

VHDL Code (Bad)

Cont’d

• Output Y– Assigned under clock’event … statement.

– Extra FFs are inferred.

Good Model 1 (1 sequential process, 1 combination process, selected signal assignment for Y)

Cont’d

Sequential process & Combinational process

• Sequential process– Description with respect to the edge point

– Input sampled just before the edge

– Output

• Combinational process

input output

FSM 2_GOOD2

• Combined current state and next state logic

• Separate output logic

Separate output logic

Cont’d

Synthesized Circuit

FSM 2_GOOD3

• Combined next state and output logic

• Separate current state logic

VHDL Code

FSM 2_GOOD4

• Combined current state, next state and output logic

VHDL Code

Car Speed Controller FSM

• State Diagram

Input primary branch directives

State value primary branch directives

Cont’d

Angular Position FSM using Gray and Johnson state encoding

• State Diagram

Cont’d

• Input– Physical Position: asynchronous input(loaded when reset = ‘1’)

– MOVE CW: 45˚ clock wise move

– MOVE CCW: 45˚ counter clock wise move

• Two ways of representing state encoding1. Use a signal of an enumerated type for which a single synthesis

specific “attribute” is applied. Attribute name is specific to the synthesis tool, not portable, needs to be changed.

VHDL Code

Cont’d

2. Use constants to represent the individual state values. It is directly portable to other synthesis tools.

Angular position FSM

Cont’d

Black Jack Game Machine

• Blackjack Game– Blackjack is the most popular of the card games played at the tables in

casinos. It is played with a standard deck of 52 cards. The four suits; spades, hearts, diamonds and clubs have no significance and are ignored. The Jack, Queen and King all have a value of 10. The ace is the most powerful card having a value of 1 or 11 depending upon what the player chooses.

– Blackjack is also known as pontoon or “21” because 21 is the highest rated total card value a player can hold. Blackjack is the name given to the strongest hand consisting of an ace and a 10 valued card.

– The object of the game is to beat the dealer. The dealer has no object other than to follow the rules of the casino, which is to stand(hold) on hands of 17 or more, and to draw another card on hands of 16 or less.

– A player looses if his or her total card value is less than the dealer’s total, or, he or she has over 21 and so has bust. If a player wants to improve his hand he can ask the dealer for another card. This is called drawing or hitting. If satisfied with the total card value he can stand(hold).

VHDL package defining four enumerated state encoding data types

FSM with selectable state encoding – Blackjack game machine

Cont’d

FSMs with a Mealy or Moore output

• State Diagram for FSMs with a Mealy and Moore output

FSM modeled with “NewColor” as a Mealy type output

Cont’d

FSM modeled with “NewColor” as a Moore type output

Cont’d

FSM modeled with a Mealy and a Moore Output

Cont’d

• Moore Output– Dependent only on the current state, early output.

FSM with sequential next state logic

• Extra FF in the next state logic.

• State Diagram– BeenlnState3B (extra FF)

FSM with sequential next state logic

Cont’d

• Inferred FSM Structure with an additional FF in the next state logic

FSM with sequential output logic

• FSM with sequential output logic– State machine with an embedded counter

• Counter: parts of the state machine’s output logic.

– State diagram implying sequential output logic

State diagram implying sequential output logic

FSM with sequential output logic

Cont’d

“Tried to use a synchronized value” 에러 발생

Inferred FSM Structure with embedded counter

FSM with sequential next state and output logic - Blackjack

• Figure 8.12 State Diagram– VHDL coded with one single process statement.

VHDL Code

Cont’d

Interactive State Machine

1. Unidirectional

Interactive State Machine

2. Bidirectional

Unidirectional interactive FSMs

• Three different ways of controlling data path with unidirectional interactive FSMs

Data Path

• Data Path– Accepts three or four 4-bits values on the input.

– Processes them, to provide sequences of either two or three, 9-bits values on the output.

– Input data: A, B, C, D

– Output data: Y1, Y2, Y3, (Y4)• When ThreeOnly = 0

Y1 = A.B + A.C

Y2 = A.D + B.C

Y3 = B.D + C.D

• When ThreeOnly = 1

Y1 = A.B + A.C

Y4 = B.C

– Data Path controlled from Control Path 1, 2, 3

Control Path 1

• Control Path– FSM master

• send Start FSM1, Start FSM2, Start FSM3

– FSM 1• Dedicated to provide four enable signals used to clock the serial input

data into the appropriate holding register.

– FSM 2• Send select signals which of the two held inputs to multiply together.

• Provide enable signals used to clock the multiplied result into the appropriate state register.

– FSM 3• Simply provide the select lines used to select which result to output.

Cont’d

• Control Signals in control path 1

Cont’d

• Master FSM state diagram and FSM1, FSM2, FSM3 state diagram

Cont’d

Control Path 2

• Three state diagram

Cont’d

• Control Path state diagram

1. Data path(VHDL Code)

Cont’d

2. Control Path 1(VHDL Code)

Cont’d

3. Control Path 2 (VHDL Code)

Cont’d

4. Control Path 3 (VHDL Code)

Cont’d

Two Interactive FSM Controlling rotors

• Two Interactive FSM Controlling rotors– To control two mechanical interlocking rotors, which rotate in 90˚

increments in a clockwise or counter clockwise.

Cont’d

• Two Interactive FSM Controlling rotors– FSM1(FSM2) controls the rotor R1(R2)

– Four states(Ang0, Ang90, Ang180, Ang270)

– Inputs: CW-R1, CCW-R1, CW-R2, CCW-R2

– Two rotors should not be in the same position

– Primary drive, Secondary drive• Cannot be in or moved to some where if it is not occupied by the

primary drive

– R1_R2b = 1: R1 is drive

R1_R2b = 0: R2 is drive

VHDL Code

Cont’d

eda lab. dept. of computer engineering c. n. u. 1 fsm structures mealy, moore and combined...

computer engineering

contd slide

y slide

good slide

vhdl code slide

synthesized circuit

angular position fsm

vhdl code bad slide

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