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:
Hack Your Roshamglo Badge
Learn how to customize and program your Roshamglo badge.
Night Sky Halloween Costume
Make a beautiful night sky costume using the LilyPad LEDs and the LilyTiny.
Qwiic Quad Relay Hookup Guide
SparkFun’s Qwiic Quad Relay is a product designed for switching not one but four high powered devices from your Arduino or other low powered microcontroller using I2C.
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.