Tag Archives: motorized locks

ATtiny85 operates (fingerprint) garage door opener

A high school sophomore known by the Instructables handle “nodcah” recently designed a DIY fingerprint scanning garage door opener powered by Atmel’s popular ATtiny85 microcontroller (MCU).

Fortunately, the DIY project isn’t limited to just garage doors, allowing Makers and tinkerers to create various types of simple motorized locks by modding the initial Instructables.

Aside from Atmel’s ATtiny85 microcontroller (MCU), key project components include:

  • 

Fingerprint scanner and JST connector
  • Serial LCD kit with Atmel’s ATmega328 MCU
  • 
PNP transistor
  • Buzzer
  • Speaker wire
  • 3D printed case
  • Copper tape
  • 5V voltage regulator
9V battery and connector
  • SPDT limit switch

“The serial LCD kit sold by Sparkfun comes with an ATmega328 MCU to control the LCD. The ATmega has extra processing power to be used for other tasks besides controlling the LCD. Because of this, we can use it as an Arduino to communicate with the fingerprint scanner, send an ATtiny85 commands, control the LCD and use a buzzer to play tones,” nodcah explained in a detailed Instructables post.

“To prevent the module from running continuously, I’ve added a limit switch to detect when the case is closed. If it’s closed, power will not be supplied to it (saves battery power).”

After gathering the above-mentioned materials, drawing the circuit and assembling the serial LCD kit, nodcah builds the circuit boards, programs the ATmega328 and ATtiny85, configures the fingerprint scanner, writes the sketch and 3D prints a basic case.

“To open the garage door I wired my module to the button that normally opens the garage. Instead of a physical connection being made, the module uses a NPN transistor to ‘press’ the button. The wires should first be measured and cut to size, leaving a little extra wire just to be safe,” nodcah added.

“Then, the hard part: soldering the wires from the button to the FPS module. The wires should next be wrapped with a generous amount of tape. To get the signal from the ATmega outside of the garage to the ATtiny inside the garage, three wires (power, ground and signal) will need to be fed through the wall. On my garage, there was a piece of wood that I just drilled right through.”

Last, but certainly not least, nodcah notes that the module’s built-in enroll feature can be used to open the garage and create personalized messages for each profile.

Interested in learning more? You can check out the project’s official Instructables page here.