Tag Archives: Biometric Fingerprint Sensor

Lock down your golf cart with ATtiny85

Some of us are lucky enough to live in communities where a typical commute is conducted within the breezy confines of a golf cart. Though, the security on a typical golf cart isn’t necessarily up to snuff.


A Maker by the name of “ramicaza” just happens to live within one of these communities and has a passion for technology. To enhance the security of his own golf cart, he installed a tinyAVR microcontroller-powered biometric fingerprint sensor that initiates his vehicle’s ignition.

Using an ATtiny85 MCU and a “GT-511C1″ fingerprint sensor from Sparkfun, the Maker created a system that enables a driver to simply scan their finger to start their cart. This simple Atmel-based controller then uses a relay to allow power to flow from the cart’s main battery to the motor. The system initiates when a custom-built switch cover is opened and then immediately displays a red LED light. Once the correct finger is scanned, the LED switches to green and the cart is ready to roll. To power down the cart, one more scan is needed and a relay powers down the vehicle. Cleverly, the circuit is designed so that if the cover is pressed while the power is on, the circuit remains active.

Ramicaza successfully replaced his cart’s ignition with home-brewed device and significantly bolstered the ‘cool factor’ of his four-wheeled ride! If you were planning on replicating this project, the Maker has shared his source code and sketches on GitHub that allows the ATtiny85 to communicate with the fingerprints scanner. “This is a sketch that allows the ATtiny line of microcontrollers to interface with the GT511-C1/3 fingerprint sensor from Sparkfun. The advantage of this sketch is that it requires no libraries and thus works on any board that can be programmed with the Arduino IDE. The sketch initializes the connection with the sensor, turns the sensors in-built LED on and continually attempts to capture finger scans. Once one is successfully captured it analyzes,” ramicaza notes.