Atto84 with Arduino Bootloader

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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.

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.

There are very tiny silkscreen pin labels on the top of the board (which correspond to the Arduino pin numbers, not the IC pin numbers) and larger labels on the bottom side of the board. A reset button allows you to put the board into bootloader mode for programming and an on-board LED attached to pin 8 makes for a handy status indicator for your project. Thin pcb construction and castellated headers make the Atto84 very low-profile but the addition of 0.1" pin headers turns it into a handy, breadboard-friendly, package.

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  • Only 28x11mm and 3.5mm tall!
  • Upload Arduino code via USB
  • 12 position, 0.4 x 0.1" DIP package
  • Flat bottom and castellated headers for surface mounting

Atto84 with Arduino Bootloader Product Help and Resources

Atto84 Hookup Guide

June 26, 2018

A bare minimum Arduino compatible breakout using a ATtiny84 for integration into your small projects!

Customer Comments

  • I had to install IDE and drivers on two computers before I could get it to load code without getting an error. Now it works! However, I tried a simple blink program to blink the built-in led. No luck. The diagram in the Atto84 hookup guide shows the built-in led as pin 8. I finally probed out the board with an led and found the pins were labeled differently than I expected. Writing to pin 2 blinks the built-in led. Here is what I found: Pin2 actually is located at pin 8 in the diagram - Writing to Pin0,Pin1, and Pin3 did not match any pins on the board diagram - Writing Pin7 is Pin3 in the diagram, Pin8 is Pin2, Pin9 is Pin1, Pin10 is Pin0, Pin 4 is PIn6, Pin5 is Pin5, Pin6 is Pin 4. GND is GND and VCC is VCC (5V on USB). The board is tiny!

  • Thanks for the excellent answers here, PickledDog. You got to them before I could!

  • Do you have any power consumption data to share? Id guess around 5ma or less powered by 5v

    • Sounds about right. You’re gonna have a constant 3mA draw from the USB D- 1.5K/Zener combo (which is unavoidable with 5V software USB), plus whatever the MCU uses. You would have to rip the USB parts off to go any lower, and they’re kinda the whole point of this board :)

  • Having not worked with the ATtiny84 yet, I have a simple question. Is it possible to connect both an I2C device and an SPI device at the same time? Specifically, I would like to attach a Nunchuck (I2C) and and NRF24L01 (SPI). These make up a simple robot remote control.

    • Sadly, it can’t. This family of Attiny chips implements SPI and I2C via a peripheral called USI (essentially the guts of a serial peripheral that provides everything you need, but doesn’t implement any specific protocol). There’s only one USI, so it can only implement one or the other. You can probably get away with bit-banging SPI for the nRF chip, though.

      • After looking at the data sheet for these, I had come to the same conclusion, but had to ask just in case. Thanks PickledDog!

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