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:
Installing a Bootloader on the MicroView
Fix your bootloader-less MicroView! This tutorial covers how to: disassemble the MicroView, wire it up to an assortment of programmers, program the bootloader, and test it out.
Night Sky Halloween Costume
Make a beautiful night sky costume using the LilyPad LEDs and the LilyTiny.
Qwiic Twist Hookup Guide
Take your volume knob beyond 11 with the Qwiic Twist digital RGB LED encoder via I2C!
SparkFun Qwiic Quad Solid State Relay Kit Hookup Guide
A Hookup Guide to get you started with the SparkFun Qwiic Quad Solid State Relay Kit (say that five times fast!).