Difference between revisions of "Knock Knock, Who's There?"

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= Timeline =
= Timeline =

Revision as of 22:39, 21 January 2016


Project Overview

This project will provide door security using a knocking pattern as encryption. A piezoelectric device will detect physical knocking on the door (or separate device). An op-amp or other amplifier and filtering will distinguish the knocking signal from noisy signals. An Arduino or similar AVR device (like the ATtiny) will interpret the pattern of knocking. An electric door lock (or other indicator for the demo, e.g. LED or solenoid) opens with a correct knocking pattern.


During the project, we will try to achieve the following:

  • Amplification/filtering of piezo signal
  • Wiring auxiliary circuitry (battery, solenoid, piezo, Arduino, etc.)
  • Successful pattern recognition using programming


Most projects run into unexpected issues. Challenges we foresee for this project include:

  • Obtaining significant amplification on piezo signal
  • Obtain a sample piezo signal using an oscilloscope
  • Using Multisim to simulate amplification and filtering
  • Coding the pattern recognition. This will require us to determine a way to save the pattern and use probability to ensure access without totally perfect knocking pattern timing
  • Using Matlab to code for minimal viable product. Then implementing on hardware.
  • Posting the system on an actual door
  • Peer management (of course)


  • Piezo-electric device ($5)
  • Op-amp or other amplifier circuitry ($20)
  • Arduino or AT-tiny ($20)
  • Battery (+holder) and voltage regulator ($10)
  • Electric door lock (or solenoid) and relay ($10)
  • Misc ($15)

Total: $80

Gantt Chart


Knock Knock Timeline.png