Finite State Recognizer

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# Finite State Recognizer - PowerPoint PPT Presentation

Finite State Recognizer. In this project, we will use the MicroStamp to function as a Finite State Recognizer (FSR). A FSR is a type of Finite State Machine that is used to identify patterns in a stream of inputs.

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Presentation Transcript
Finite State Recognizer
• In this project, we will use the MicroStamp to function as a Finite State Recognizer (FSR). A FSR is a type of Finite State Machine that is used to identify patterns in a stream of inputs.
• One example is in data comm, where a frame or packet includes special characters – to identify the start of end of a frame, or other control purposes. The machine monitors the stream of incoming bits, and generates a signal or interrupt upon recognizing a control character.
• Another classic example is a drink machine, that counts coins until the price has been reached, then allows a drink to be released.

A

• Note: In a course on digital logic, the construction of a FSR is a classic lab exercise.
• A FSR can be represented with a graph of states, transitions, and inputs:

State

Transition

Input/Output

1/0

0/0

0/0

1/0

Start

A

D

C

B

1/0

0/0

1/1

0/0

1/0

FSR Example
• A FSR for the pattern 1101: (non overlapping)

States:

A: haven’t seen anything yet

B: have seen a “1”

C: have seen a “11”

D: have seen a “110”

Note that each state has two transitions leaving it (binary).

Check: 1100, 11101, 1101101

A

D

C

B

FSR Example
• A FSR for the pattern 1101: (overlapping patterns)

0/0

0/0

A: haven’t seen anything yet

B: have seen a “1”

C: have seen a “11”

D: have seen a “110”

This version recognizes 1101 twice in this pattern:

1101101

1/0

Start

1/0

0/0

1/1

0/0

1/0

A

D

C

B

FSR Example
• A FSR for the pattern 0110: (Overlapping patterns)

0/0

1/0

A: haven’t seen anything yet

B: have seen a “0”

C: have seen a “01”

D: have seen a “011”

This version recognizes 0110 twice in this pattern:

0110110

0/0

Start

1/0

0/0

1/0

0/1

1/0

• Write a program for the MicroStamp11 to recognize the sequence: 1011. Allow overlapping patterns.
• Use a switch for the arriving input bit.
• Use a pushbutton switch to signal the micro-controller that a new bit has arrived, that it needs to check.
• When the sequence is recognized, light LED 7.
• For debugging, and as a check, the current “state” of the machine will be displayed using LEDs 1&0:
• 00 – A
• 01 – B
• 10 – C
• 11 - D

Use pushbutton switch B to signal that data has arrived.

You may choose to use SW0-7 for the data bit

Lab project continued
• Include a FSR diagram for 1011.
• Include a initial flowchart for your first design.
• Include a final flowchart of your program that works.
• We will use Wed of this week, and Monday of next week for lab time.
• Last class day is Wed December 11.
• Final exam is: (6:30pm MW classes)
• December 16, 6:30pm-8:30pm

Start

Next State

Input Loop

Get Input

Display State Subroutine

High-Level Design Suggestions

Push Button Pressed