Atto84 Hookup Guide

Contributors: Nick Poole
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Introduction: The Littlest 'Duino

Arduino and Arduino compatible dev boards are an awesome tool for developing an idea quickly but, being development boards, they're often a little more bulky and full featured than you really need. Having a USB interface and a bootloader is so nice, though, so we put together the bare minimum Arduino compatible breakout for integration into your small projects. We call it the Atto84.

Atto84 with Arduino Bootloader

Atto84 with Arduino Bootloader


The Atto84 is essentially a breakout board for the absolutely minute WQFN ATtiny84, but we've done some work to make it easier to program. First off, we've added a micro-USB connector and a firmware-based USB driver for the ATtiny that allows you to program the chip over USB. In addition, we've created an Arduino board profile that combines this bootloader with an extremely full-featured ATtiny Arduino core.

Simply install the USB drivers on your computer, select the board profile from Arduino's Board Manager, and upload code to this board like any other Arduino style development board. In this hookup guide, you'll learn how to do exactly that!

Suggested Reading

If you aren’t familiar with the following concepts, we recommend checking out these tutorials.

Serial Peripheral Interface (SPI)

SPI is commonly used to connect microcontrollers to peripherals such as sensors, shift registers, and SD cards.


An introduction to I2C, one of the main embedded communications protocols in use today.

How to Solder: Castellated Mounting Holes

Tutorial showing how to solder castellated holes (or castellations). This might come in handy if you need to solder a module or PCB to another PCB. These castellations are becoming popular with integrated WiFi and Bluetooth modules.

How to Install an ATtiny Bootloader With Virtual USB

With this, you will be able to upload Arduino sketches directly to the ATtiny84 over USB without needing to use a programming device (such as another Arduino or FTDI chip).