Adafruit
Adafruit ATtiny817 Breakout with seesaw - STEMMA QT / Qwiic
The Adafruit ATtiny817 Breakout with seesaw is a compact development board that combines an ATtiny817 microcontroller with the Adafruit seesaw I2C framework ...
The Adafruit ATtiny817 Breakout with seesaw is a compact development board that combines an ATtiny817 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 can also be reprogrammed as a general-purpose ATtiny817 development board using the megaTinyCore Arduino core. With STEMMA QT connectors, it works seamlessly as either an I2C controller or peripheral with plug-and-play support.
Key Features
- ATtiny817 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
- 14× GPIO – With selectable pullup resistors
- 9× 10-bit ADC Inputs – Pins 0, 1, 2, 3, 6, 7, 18, 19, 20
- 5× 8-bit PWM Outputs – Pins 0, 1, 9, 12, 13
- 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 15, triggered by any configured peripheral
- 2× I2C Address Selection Pins – Pins 16 and 17 for running multiple boards on one bus
- 2× STEMMA QT / Qwiic Connectors – Plug-and-play I2C with 10K pullup resistors (pins 10, 11)
- 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 5
Also Available
- ATtiny1616 Seesaw Breakout with STEMMA QT – More memory (16KB flash, 2KB RAM) and up to 250 NeoPixels
- ATtiny816 Seesaw Breakout with STEMMA QT – Same memory, different pin mapping
- ATSAMD09 Seesaw Breakout – Original seesaw breakout with ARM Cortex-M0+
Ideal For
- Adding extra I/O to Raspberry Pi, ESP32, or Arduino projects via I2C
- NeoPixel control from I2C-only platforms
- ATtiny817 development and prototyping
- Seesaw firmware customisation and testing
Package Contents
- 1× Adafruit ATtiny817 Breakout with seesaw
- 1× Header strip set
Jargon buster
Plain-language definitions for the technical terms used above.
- 3.3V regulator
- A 3.3V regulator is a power circuit that provides a steady 3.3 volts for parts that need that supply voltage. On a breakout board, it can let the sensor run safely even when the connected microcontroller or power source uses a higher voltage.
- ADC
- An analogue-to-digital converter reads a changing voltage and turns it into a number the microcontroller can use. It matters when connecting analogue sensors such as light, sound, or variable-resistor sensors.
- Bootloader
- Small starter software on a microcontroller that lets new code be uploaded before the main program runs. Knowing how to enter bootloader mode matters when you need to program the board or recover it after a faulty sketch.
- breakout
- A breakout is a small circuit board that makes a tiny or hard-to-solder component easier to connect to with standard pins. It matters because this OLED module can be wired into a microcontroller project without needing to solder directly to the display’s fine contacts.
- EEPROM
- A type of non-volatile memory that keeps stored data even when power is turned off. In a sensor module, it can be used to store settings or calibration data so they do not need to be re-entered every time.
- ESP32
- ESP32 is a family of microcontroller modules with built-in wireless features such as Bluetooth and WiFi. Knowing this product uses an ESP32-based module helps explain how it provides wireless serial communication and firmware update features.
- GPIO
- General-purpose input/output pins are microcontroller pins you can set in software to read signals, switch devices on and off, or connect to peripherals. The number of GPIO pins matters because it limits how many buttons, LEDs, sensors, and other parts you can wire directly to the board.
- I2C
- I2C is a two-wire communication bus used by many sensors and small modules. It matters because several I2C devices can share the same two wires, but each device needs a compatible address and your controller must support I2C.
- I2C address
- An I2C address is the number a device uses so a microcontroller can tell it apart from other devices on the same I2C bus. It matters because two devices with the same fixed address may conflict if used together.
- LED
- A light-emitting diode is a small electronic component that lights up when current flows through it in the correct direction. In this kit, LEDs create the flashing effect, so polarity and correct soldering matter for the project to work.
- microcontroller
- A microcontroller is a small computer on a chip that runs your program and controls connected inputs and outputs. For this product, it is the part that reads buttons and sensors, drives the display and speaker, and communicates over Bluetooth.
- NeoPixel
- A type of addressable LED system where colour data is sent along a single digital data line from one LED or controller to the next. Compatibility matters because the timing and signal format must match for the lights or driver board to respond correctly.
- PWM
- Pulse Width Modulation is a way for a digital pin to simulate variable output power by switching on and off very quickly. It matters for controlling things like LED brightness, motor speed, or servo-style signals from a microcontroller pin.
- Qwiic
- Qwiic is a plug-in connector system for I2C devices that uses small 4-pin cables, so you can connect compatible sensors without soldering. It matters because your controller or adapter also needs Qwiic, or you will need a cable or breakout to wire it up.
- RAM
- RAM is temporary memory used while a device is running, and its contents are lost when power is removed. A “Run in RAM” mode is useful for testing settings without permanently programming the module, but it may not support every feature.
- solder jumper
- A solder jumper is a small pair or group of pads on a circuit board that can be bridged or cut with solder to change a hardware setting. It matters because changing modes may require careful soldering rather than just changing software.
- STEMMA
- A plug-and-cable connection system used on some maker electronics boards to make wiring simpler. If a product uses STEMMA, you need the matching cable or connector type to plug it in without soldering.
- STEMMA QT
- A small plug-in connector system for I2C boards that lets you connect compatible sensors and controllers without soldering. It matters because it can make wiring faster and less error-prone, especially when adding several small modules to a project.
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