# Adafruit ATtiny816 Breakout with seesaw - STEMMA QT / Qwiic

**Type:** Product page · **SKU:** ADA5681 · **Brand:** [Adafruit](https://core-electronics.com.au/brands/adafruit-australia)
**Page:** https://core-electronics.com.au/adafruit-attiny816-breakout-with-seesaw-stemma-qt-qwiic.html ([markdown](https://core-electronics.com.au/adafruit-attiny816-breakout-with-seesaw-stemma-qt-qwiic.html.md))

This breakout board is a "three in one" product:The ATtiny816 is part of the 'next gen' of AVR microcontrollers, and now we have a cute...

## Pricing

- **Price:** $8.80 (inc GST) — $8.00 AUD, exc GST
- **Quantity discounts:** 10+ $7.76 (exc GST) · 50+ $7.60 (exc GST)

## Availability & dispatch

- Available with a lead time — expect dispatch between Aug 24 and Aug 28.

## Description

This breakout board is a "three in one" product:

1. The ATtiny816 is part of the 'next gen' of AVR microcontrollers, and now Adafruit have a cute development/breakout board for it, with just enough hardware to get the chip up and running.
2. It's also an Adafruit seesaw board. Adafruit seesaw is a near-universal converter framework which allows you to add and extend hardware support to any I2C-capable microcontroller or microcomputer. Instead of getting separate I2C GPIO expanders, ADCs, PWM drivers, etc, seesaw can be configured to give a wide range of capabilities.
3. Finally, with STEMMA QT connectors on it, you could use it as either an I2C controller or peripheral with plug-and play support.

Adafruit primarily designed this board for Adafruit's own use: it's a mini dev board that lets Adafruit design with the ATtiny816 [just like Adafruit did for the ATSAMD09](https://core-electronics.com.au/adafruit-atsamd09-breakout-with-seesaw.html). With the 2021-2022 silicon shortage, Adafruit are adapting some of Adafruit's SAMD09 designs to the ATTiny8xx series and wanted a quick minimal board to test code on.

Each breakout comes with the assembled and tested board, as well as some header strips. Each PCB is fairly minimal and contains:

- **ATtiny816 8-bit microcontroller**
    - 8KB flash, 512 bytes of RAM, 128 bytes of EEPROM
    - Internal oscillator can run up to 20MHz
    - Internal hardware multiplier
    - Can run from 2V to 5V power/logic (check the datasheet for max speed at desired power)
- **3.3V regulator** - by default Adafruit run at the Vin voltage, which can be 5V, but there's a solder jumper on the bottom if you'd like to select 3V logic.
- **Green power LED**
- **Red indicator LED**
- **Two STEMMA QT I2C connectors** with 10K pullup resistors, connected to pins 8 and 9

[This board comes pre-programmed with seesaw peripheral code](https://github.com/adafruit/Adafruit_seesawPeripheral) that will let it act as an "I2C to something" converter, basically a little I2C-controlled friend to do all the timing-sensitive things many microcontrollers and microcomputers are not good at.

For example, using this breakout with the pre-burned seesaw firmware gives you

- 12 x GPIO with selectable pullup resistors: 0-5, 6, 8, 11, 14, 15, 16
- 9 x 10-bit ADC inputs - pins 0, 1, 2, 3, 4, 5, 14, 15, 16
- 5 x 8-bit PWM outputs - pins 0, 1, 7, 11, 16
- 1 x NeoPixel output (up to 60 pixels)
- 1 x EEPROM with 127 byte of NVM memory (handy for storing small access tokens or MAC addresses) - last byte of EEPROM is used for I2C address selection
- 1 x Interrupt output that can be triggered by any of the accessories - pin 6
- 2 x I2C address selection pins - pins 12 and 13
- 1 x Activity LED on pin 10, tied active low

Of course, you can configure or reprogram the chip to however you want to use it - [Adafruit like using SpenceKonde's megaTinyCore which brings Arduino peripheral support](https://github.com/SpenceKonde/megaTinyCore) to this series of chips. To program the chip [you will need a 'UPDI' programmer](https://github.com/SpenceKonde/megaTinyCore), which you can make with a [USB-to-Serial cable](https://core-electronics.com.au/usb-to-ttl-serial-cable-debug-console-cable-for-raspberry-pi.html) and [a single 4.7K or 10K resistor](https://core-electronics.com.au/catalog/product/view/sku/ADA2783).

**Please note:** The boards do not come with a bootloader. If you want to do development on seesaw (e.g. changing the configuration) you need a separate UPDI programming setup! [The firmware Adafruit put on is available as this example sketch](https://github.com/adafruit/Adafruit_seesawPeripheral/blob/main/examples/example_pid5681/example_pid5681.ino), compiled using the megaTinyCore. Adafruit don't provide any support for custom builds of seesaw - we think this is cool and useful for the Maker community!

[For more details including the documentation on how to use seesaw, libraries for Arduino/CircuitPython/Raspberry Pi Python, schematics, and more check out the Adafruit seesaw guide](https://learn.adafruit.com/adafruit-attiny817-seesaw)

## Technical Details 

![RoHS 2 2011 65 EU Compliant](https://core-electronics.com.au/attachments/localcontent/RoHS2_2011_65_EU_7356c5574c.svg)![RoHS 2 2015 863 EU Compliant](https://core-electronics.com.au/attachments/localcontent/RoHS2_2015_863_EU_86773f57f9.svg)

## Images

- [Product image 1](https://core-electronics.com.au/media/catalog/product/A/D/ADA5681-1.jpg)