There are two scripts one for PINs with 4 or 5 digits and one for PINs with 6 to 8 digits. The scripts are made for the ATTiny85 however the logic can be applied to any HID (Human Interface Device) ...
You can free up a few pins on the ATtiny85 by foregoing an external crystal oscillator in favor of the ATtiny's internal oscillator. However, the internal oscillator is much less accurate than an ...