Keep Your Valuable Possessions Secured with This Fingerprint Safe

from hackster.io

For a safe, keeping the items stored within it secured is its number one priority, but having to enter in a secret code or find a small key each time the safe needs to be opened can be a painstaking process.

This is what drove one Instructables user, Adi Miller, to take an old digital safe he had lying around and repurpose it into a modern device with a fingerprint reader. By creating this project, he could dramatically reduce the amount of time required to open the box and also give access for up to 126 others.

Perhaps the most important component of this project, Miller went with an R503 fingerprint sensor. It differs quite substantially from the traditional optical sensor in that it uses a capacitive pad which senses the ridges along a finger rather than scanning them with a light and camera.

To drive everything, an ESP8266 module was connected via UART to the fingerprint sensor in order to send commands and know when a print has been detected. To unlock the door, a solenoid was added that gets powered via a relay whenever power is applied. Lastly, the ten-digit matrix keypad was wired to seven digital pins along with a buzzer for signaling when an attempt to sign in was successful.

A safe as old as the one Miller used needed a few modifications in order to function as he intended. First, the cylinder which housed the physical key mechanism was replaced by the fingerprint sensor.

Next, the locking solenoid was attached just below the sliding bolt that moves it when the door is unlocked. The remaining electronics and power supply were all placed behind the front door and wired together.

Within an infinite loop, the program checks several things, including if the user wants to enroll a new fingerprint. If that is the case, a slot is chosen in which to either add new data or replace preexisting data. The final step of this process has the user place their finger over the sensor twice and then beeps to confirm it.

As seen in Miller's video demonstrating his project, the safe is able to successfully enroll new users, reject unknown ones, and opens when a known print is detected. And even though the ESP8266 supports WiFi connectivity, his code doesn't expose the current status of the safe, but it can certainly be added in the future.

You can read more about this DIY fingerprint safe conversion here in its write-up on Instructables, and the code can be viewed on GitHub.