The downside is that micronucleus uses 2k of the available flash, leaving us with only 6k of flash for our program! A bootloader like micronucleus allows us to upload firmware to the microcontroller over a 'virtual' USB (V-USB) connection rather than using a separate microcontroller for programming. The ATtiny84 and 85 have 8k of flash memory (compared to 32k in the ATmega328p, the most commonly found microcontroller on Arduino platforms). The ATtiny microcontrollers are fantastic little chips but often suffer from low programming space. Upload example firmware from Arduino IDE to the ATtiny84.

Create a new board definition in Arduino for the ATtiny84.Manually change fuses in the ATtiny84 to allow USB programming.Install the micronucleus bootloader on the ATtiny84.Load Arduino ISP (In-System Programmer) on an Arduino.Do this at your own risk! SparkFun takes no responsibility if you brick/smoke/blow up your ATtiny. Note that this is out of spec for the ATtiny84! We're essentially overclocking/hacking the ATtiny to do something it's not supposed to do. This tutorial shows how to do that with the internal RC clock at 3.3V. Warning: To make this work, we'll need to run the ATtiny84 at 12MHz during the bootloader phase.

Arduino wire library set timeout