Keyless Unlock System

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1212 Views Posted on: 06/16/2021

Keyless Unlock System Header Image

Overview:

This project is designed to keylessly lock and unlock the door by knocking. The device makes it convenient for the user since the user does not need a key to lock the door especially when the user is racing against time. Users can unlock the door by using a secret knock, the secret knock pattern can easily be changed by a user.

Supplies

In order to achieve this project, the essential components are shown below:

Step 1: Setup Piezo Sensor

Setup Piezo Sensor

Piezo sensor converts press or squeeze into measurable electrical charges. By observing the value of the electrical charges, the knocking pattern can be extracted. The circuit of the piezo sensor shows above, the piezo sensor connected parallelly with a 1M Ohm resistor and to the ground and analog pin on the Arduino UNO.

Step 2: Setup Push Button

Setup Push Button

The function of the push button is to change the knock password, when the push button is pressed and held, the system will erase the existing knock password, meanwhile, the system records the knocks pattern until the button has been released. The system records the new knock pattern and saves it as a new password. The circuit of the button shows above, the resistance used in this circuit is 100K OHM.

Step 3: Setup Solenoid

Setup Solenoid
Setup Solenoid

To lock and unlock the door, a 12V solenoid is used. The solenoid is a normally closed device, the latch unlocks when the solenoid is activated by a 12V power and vice versa. Arduino Uno can only output 5V and 3.3V which cannot activate the 12V solenoid. To solve this problem a 12V relay module shown is needed.

The figure above with a red board is the structure of the relay module (PID: 18405), DC+ and DC- connect to the 12VDC power. The pin IN controls the connection of the output pins (NO, COM, and NC), NO and COM connect together when pin IN receives 5V and vice versa. In this project, the pin IN is controlled by the Arduino UNO and the circuit shown above.

Step 4: Coding: Part 1

Posted in: Projects, Starter Projects

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