How to Install an ATtiny Bootloader With Virtual USB
Contributors:
Shawn Hymel
Shawn Hymel 
Resources and Going Further
While this is a lot of information to take in, it shows how to hack the Arduino IDE to load custom board definitions. These steps should work for other ATtiny devices that are supported by the micronucleus project, such as:
You might have to modify the pins_arduino.h file, however, if you plan to use a different ATtiny.
ATtiny84 Pinout
If you need additional support, please check out the following resources.
If you want to go further with the ATtiny, please check out our additional tutorials that showcase the ATtiny:
Qwiic Keypad Hookup Guide
If you are tired of taking up GPIO pins, wiring a bunch of pull up resistors, and using firmware that scans the keys taking up valuable processing time... check out the new Qwiic Keypad.
Electronic E-craft Terrarium
A guest tutorial on an Electronic Terrarium from the Performative Sculpture class of Parsons DT.
Qwiic MP3 Trigger Hookup Guide
Playing MP3s has never been easier.
SparkFun Qwiic Button Hookup Guide
A Hookup Guide for the SparkFun Qwiic Button (Red) and SparkFun Qwiic Button Breakout. Goes over connecting the Qwiic Button to an Arduino microcontroller and using it with the Qwiic Button Arduino library.