Finite State Recognizer

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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.

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• 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
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FSR Example

• A FSR for the pattern 1101 (non overlapping)

States A havent 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
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FSR Example

• A FSR for the pattern 1101 (overlapping
  patterns)

0/0
0/0
A havent 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
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FSR Example

• A FSR for the pattern 0110 (Overlapping patterns)

0/0
1/0
A havent 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
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Your next lab project

• 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 10
• 00 A
• 01 B
• 10 C
• 11 - D

7
Use pushbutton switch B to signal that data has
arrived.
You may choose to use SW0-7 for the data bit
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Lab project continued

• Document your project in your lab notebook.
• 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 (630pm MW classes)
• December 16, 630pm-830pm

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High-Level Design Suggestions
Push Button Pressed