What is sequence detector in digital electronics?

Answer 1

Sequence detection is the act of recognizing a predefined series of inputs. In our case, we are

looking for very simple things very slowly. We are looking for a series of ones and zeros similar to

1011. The overwhelming beauty of programmable logic is its ability to work with DSP (digital

signal processing). The capability of processing a great deal of information quickly can not be

overemphasized. Suppose you were working at the VLA in Socorro and you wanted to scan

thousands of bits of digital information looking for a series of bits that represents an RF signal

from a distant galaxy. Or, suppose you wanted to scan a digital image of a human lung looking for

a digital signature that could represent a cancerous cell. These are very broad interpretations but

I believe you can see where the benefits come in with being able to recognize a specific

sequence.

A sequence detector is a sequential circuit which is basically a circuit that can store information

between operations. There are two main models for sequential circuits: Mealy and Moore model.

A Mealy model circuit the output depends on the inputs and the state of the system, in a Moore

model, the output of the system only depends on its state. Please review your class notes on

state diagrams for sequential circuits.

Design a Sequence Detector

For this lab we’ll need to create a sequence detector with the following characteristics:

• Serial input X

• The sequence to be detected is 10010.

• Five bits wide output Z with value 00000 when no sequence is detected, 00001 when the

first bit of the sequence is detected, 00010 for the second bit, 00100 for the third bit,

01000 for the fourth and 10000 when the whole sequence is detected.

• If input Y is one, the system is reset to output 00000.

This is a sequential circuit; therefore we will need a clock. Since the XCR board we are working

with does not include a clock, we will use the slowest clock we have: your finger!