How the Circuit Works

The Arduino Nano is programmed to communicate with a Servo and Fingerprint Sensor. The Fingerprint sensor is preprogrammed with a library of Fingerprints that you want to be able to unlock the Diary Door.

The door lock button is used to actuate the locking mechanism when the lid is closed. An infrared sensor is used to detect that the door is closed.

I have used WS2182 LEDs which have a built-in IC which enables them to be addressed by the Arduino using three separate wires however a broad range of colors and brightnesses color can be created by sending a command to the LED. This is done through a special library loaded into the Arduino IDE covered in the testing section.

Build and Test the Fingerprint Reader Circuit

Assemble the circuit on a Breadboard following the circuit diagram provided.

The following Libraries need to be downloaded and added to the Arduino IDE before loading the program into the Arduino Nano

FastLED.h

Adafruit_Fingerprint.h

Load the Adafruit_enroll_fingerprints.INO file and follow the prompts to enroll 10 new fingerprints in the first 10 locations. My advice is to use two separate fingers 5 times so that you can be sure of a reliable unlock of the unit.

Test the Unit

Load the Biometric_Personal_Diary.INO file and load the code into the Arduino Nano. Test the door lock button is operating the locking mechanism when the infrared sensor is blocked simulating the lid being is closed. On power up the blue LED startup sequence occurs. The Servo should be stable and not be chattering after initial powerup.

Once powered up, with the Infrared Sensor Blocked the green Light within the Finger Print Sensor should turn on. At this point, the unit is ready to read a fingerprint. Place your previously scanned and recorded finger on the sensor and hold until the LEDs indicate a reading has been completed. If the LEDs are red then the fingerprint is not recognized and the unit will try to continue to read. If the LEDs are green then the fingerprint has been recognized and you should see the Servo actuate. (See the video clip of the test above)