Adafruit ATtiny Breakouts with seesaw

A STEMMA QT to ... whatever! interface.

by Kattni Rembor and Liz Clark

published October 20, 2021, last edited August 07, 2025
last major update February 28, 2023

posted in Adafruit Products Arduino Compatibles CircuitPython Breakout Boards STEMMA

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Beginner

Product guide

Arduino

The Adafruit Seesaw library makes it easy to use your ATtinyxxx breakout with Arduino. Install the necessary libraries, and load the examples to use your ATtinyxxx breakout for all sorts of purposes. This example is designed to verify that your breakout is working - it simply blinks the built-in LED. No hardware other than the breakout and microcontroller is needed.

Though the Fritzing diagrams depict an ATtiny817, the examples work as written with the ATtiny816 and ATtiny1616.

Wiring

You can use many different Arduino boards, but this example shows the QT Py M0, and the Adafruit Metro. Connect up the ATtiny817 breakout as shown below.

Here is the QT Py wired up:

Use a STEMMA QT cable to connect the STEMMA QT connector on the QT Py to the STEMMA QT connector on the breakout.

Here is the Metro wired up:

Plug a STEMMA QT to male jumper wire cable into the STEMMA QT connector on the breakout.
Metro 5V to breakout VIN (red wire)
Metro GND to breakout GND (black wire)
Metro SCL to breakout SCL (yellow wire)
Metro SDA to breakout SDA (blue wire)

Library Installation

You can install the Adafruit Seesaw Library for Arduino using the Library Manager in the Arduino IDE:

Click the Manage Libraries ... menu item, search for seesaw, and select the Adafruit Seesaw library:

adafruit_products_ATtinyB_Arduino_seesaw_lib_install.png

If asked to install dependencies, choose Install all.

adafruit_products_ATtinyB_Arduino_dependency_install.png

Load Example

Open up File -> Examples -> Adafruit Seesaw -> digital -> attiny_blink and upload to your Arduino wired up to the breakout.

Upload the sketch to your board and open up the Serial Monitor (Tools->Serial Monitor). You should see seesaw started ok!. If you don't, check your wiring.

If using the STEMMA QT version of the board, you'll need to use Wire1 like this: Adafruit_seesaw ss(&Wire1) ;

The example below is for the 817. If you are using the 816/1616, please change #define BLINK_PIN 5 to #define BLINK_PIN 10. No other changes are needed.

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/*
 * This example shows how to blink a pin on a seesaw.
 * It is written to use the built-in LED on the ATtiny817 breakout with seesaw.
 */

#include "Adafruit_seesaw.h"

Adafruit_seesaw ss;

#define BLINK_PIN 5

void setup() {
  Serial.begin(115200);
  
  while (!Serial) delay(10);   // wait until serial port is opened
  
  if(!ss.begin()){
    Serial.println("seesaw not found!");
    while(1) delay(10);
  }
  
  Serial.println(F("seesaw started OK!"));

  ss.pinMode(BLINK_PIN, OUTPUT);
}

void loop() {
  ss.digitalWrite(BLINK_PIN, LOW);   // turn the LED on (the LED is tied low)
  delay(1000);                       // wait for a second
  ss.digitalWrite(BLINK_PIN, HIGH);    // turn the LED off
  delay(1000);  
}

/*
 * This example shows how to blink a pin on a seesaw.
 * It is written to use the built-in LED on the ATtiny817 breakout with seesaw.
 */

#include "Adafruit_seesaw.h"

Adafruit_seesaw ss;

#define BLINK_PIN 5

void setup() {
  Serial.begin(115200);
  
  while (!Serial) delay(10);   // wait until serial port is opened
  
  if(!ss.begin()){
    Serial.println("seesaw not found!");
    while(1) delay(10);
  }
  
  Serial.println(F("seesaw started OK!"));

  ss.pinMode(BLINK_PIN, OUTPUT);
}

void loop() {
  ss.digitalWrite(BLINK_PIN, LOW);   // turn the LED on (the LED is tied low)
  delay(1000);                       // wait for a second
  ss.digitalWrite(BLINK_PIN, HIGH);    // turn the LED off
  delay(1000);  
}

Once you've successfully loaded the sketch onto your board, the little red LED will begin blinking!