The Adafruit ATtiny816 Breakout with seesaw is a compact development board that combines an ATtiny816 microcontroller with the Adafruit seesaw I2C framework and STEMMA QT connectivity. Pre-programmed with seesaw firmware, it acts as an I2C-controlled co-processor — adding GPIO, ADC, PWM, and NeoPixel support to any I2C-capable host.

This board offers the same pin layout and seesaw capabilities as the ATtiny1616 variant but with a smaller memory footprint, making it a cost-effective option for projects that don't need the extra flash and RAM. It can also be reprogrammed as a general-purpose ATtiny816 development board using the megaTinyCore Arduino core.

Key Features

• ATtiny816 Microcontroller – 8KB flash, 512 bytes RAM, 128 bytes EEPROM, internal oscillator up to 20 MHz, hardware multiplier
• Seesaw I2C Framework – Universal converter providing GPIO, ADC, PWM, and NeoPixel control over I2C
• 12× GPIO – Pins 0–5, 6, 8, 11, 14, 15, 16 with selectable pullup resistors
• 9× 10-bit ADC Inputs – Pins 0, 1, 2, 3, 4, 5, 14, 15, 16
• 5× 8-bit PWM Outputs – Pins 0, 1, 7, 11, 16
• NeoPixel Output – Drive up to 60 NeoPixel LEDs from a single pin
• 127-byte EEPROM – Non-volatile memory for tokens or MAC addresses (last byte used for I2C address)
• Interrupt Output – Pin 6, triggered by any configured peripheral
• 2× I2C Address Selection Pins – Pins 12 and 13 for running multiple boards on one bus
• 2× STEMMA QT / Qwiic Connectors – Plug-and-play I2C with 10K pullup resistors
• 3.3V Regulator – Runs at Vin by default (up to 5V); solder jumper to select 3.3V logic
• 2V to 5V Operation – Wide voltage range for flexible integration
• Power and Activity LEDs – Green power LED, red indicator LED on pin 10

Also Available

• ATtiny1616 Seesaw Breakout with STEMMA QT – More memory (16KB flash, 2KB RAM) and up to 250 NeoPixels
• ATSAMD09 Seesaw Breakout – Original seesaw breakout with ARM Cortex-M0+ (requires J-Link for reprogramming)

Ideal For

• Adding extra I/O to Raspberry Pi, ESP32, or Arduino projects via I2C
• NeoPixel control from I2C-only platforms
• ATtiny816 development and prototyping
• Cost-effective seesaw peripheral in space-constrained designs

Package Contents

• 1× Adafruit ATtiny816 Breakout with seesaw
• 1× Header strip set