Adafruit ANO Rotary Encoder — XIAO Accessory Guide

Product 5740: ANO Rotary Encoder to I2C Adapter

Compatible XIAO Boards

Pinout and Wiring

ANO Rotary Encoder Pinout

    ┌─────────────────┐
    │  ANO Rotary      │
    │  Encoder         │
    │                 │
    │  +------------+  │
    │  |  +---+
    │  +---+   |
    │      |   |
    +------+   +-----+
    │ GND  │ 3V3  │
    │ SDA  │ SCL  │
    │ INT  │ NEO  │
    └──────────────┘

Pin Description

Wiring Diagrams by XIAO Board

XIAO SAMD21 / RP2040 / nRF52840 / ESP32S3

XIAO                  ANO Rotary Encoder
────                  ──────────────────
D4  (SDA)     ────   SDA
D5  (SCL)     ────   SCL
3V3           ────   3V3
GND           ────   GND
(optional)
Any GPIO      ────   INT

XIAO ESP32C6

XIAO                  ANO Rotary Encoder
────                  ──────────────────
D1  (SDA)     ────   SDA
D0  (SCL)     ────   SCL
3V3           ────   3V3
GND           ────   GND
(optional)
Any GPIO      ────   INT

Library Installation

Arduino (Adafruit Seesaw)

1. Open Arduino IDE
2. Go to Sketch → Include Library → Manage Libraries
3. Search for "Adafruit seesaw" and install
4. The library includes examples for encoder reading

CircuitPython / Python

# Using pip
pip install adafruit_seesaw

# Or for a specific board
pip install adafruit-circuitpython-seesaw

Arduino C++ Examples

Basic Encoder Reading

#include <Wire.h>
#include "Adafruit_seesaw.h"

Adafruit_seesaw ss;

void setup() {
    Serial.begin(115200);
    
    if (!ss.begin(0x49)) {  // Default I2C address
        Serial.println("Seesaw not found!");
        while (1) delay(10);
    }
    Serial.println("Seesaw started!");
}

void loop() {
    int32_t encoderPosition = ss.getEncoderPosition();
    Serial.print("Encoder position: ");
    Serial.println(encoderPosition);
    
    delay(100);
}

Encoder with LED Control (Product 4991)

#include <Wire.h>
#include "Adafruit_seesaw.h"
#include "Adafruit_NeoPixel.h"

#define SEESAW_ADDR 0x49
#define NEO_PIN 6  // NeoPixel pin on seesaw

Adafruit_seesaw ss;
Adafruit_NeoPixel pixels(1, NEO_PIN + 18, NEO_GRB + NEO_KHZ800);

void setup() {
    Serial.begin(115200);
    
    if (!ss.begin(SEESAW_ADDR)) {
        Serial.println("Seesaw not found!");
        while (1) delay(10);
    }
    
    pixels.begin();
    pixels.setBrightness(50);
    pixels.show();
    
    Serial.println("ANO Rotary Encoder ready!");
}

void loop() {
    int32_t encoderPosition = ss.getEncoderPosition();
    Serial.print("Position: ");
    Serial.println(encoderPosition);
    
    // Color based on position
    uint32_t color;
    switch (encoderPosition % 3) {
        case 0: color = pixels.Color(255, 0, 0); break;   // Red
        case 1: color = pixels.Color(0, 255, 0); break;   // Green
        case 2: color = pixels.Color(0, 0, 255); break;   // Blue
    }
    pixels.fill(color);
    pixels.show();
    
    delay(100);
}

Interrupt-Based Reading

#include <Wire.h>
#include "Adafruit_seesaw.h"

#define SEESAW_ADDR 0x49
#define INT_PIN 2  // Connect INT to GPIO2

Adafruit_seesaw ss;
volatile int32_t encoderPosition = 0;

void setup() {
    Serial.begin(115200);
    
    if (!ss.begin(SEESAW_ADDR)) {
        Serial.println("Seesaw not found!");
        while (1) delay(10);
    }
    
    // Enable encoder interrupts on seesaw
    ss.enableEncoderInterrupt();
    
    // Set up interrupt pin
    pinMode(INT_PIN, INPUT_PULLUP);
    attachInterrupt(digitalPinToInterrupt(INT_PIN), encoderISR, FALLING);
    
    Serial.println("Interrupt-based encoder ready!");
}

void loop() {
    static int32_t lastPosition = 0;
    
    // Read position only when changed (via polling fallback)
    int32_t newPosition = ss.getEncoderPosition();
    if (newPosition != lastPosition) {
        Serial.print("Position: ");
        Serial.println(newPosition);
        lastPosition = newPosition;
    }
    
    delay(10);
}

void encoderISR() {
    // This fires when seesaw triggers interrupt
    // Read actual position in loop to avoid I2C in ISR
}

Multi-Encoder with Different Addresses

#include <Wire.h>
#include "Adafruit_seesaw.h"

#define ADDR_ENCODER1 0x49
#define ADDR_ENCODER2 0x4A

Adafruit_seesaw encoder1;
Adafruit_seesaw encoder2;

void setup() {
    Serial.begin(115200);
    
    if (!encoder1.begin(ADDR_ENCODER1)) {
        Serial.println("Encoder 1 not found!");
        while (1) delay(10);
    }
    
    if (!encoder2.begin(ADDR_ENCODER2)) {
        Serial.println("Encoder 2 not found!");
        while (1) delay(10);
    }
    
    Serial.println("Both encoders ready!");
}

void loop() {
    int32_t pos1 = encoder1.getEncoderPosition();
    int32_t pos2 = encoder2.getEncoderPosition();
    
    Serial.print("Encoder 1: ");
    Serial.print(pos1);
    Serial.print(" | Encoder 2: ");
    Serial.println(pos2);
    
    delay(100);
}

CircuitPython / Python Examples

Basic Reading

import board
import busio
from adafruit_seesaw.seesaw import Seesaw

# Initialize I2C
i2c = busio.I2C(board.SCL, board.SDA)

# Create seesaw instance
ss = Seesaw(i2c, addr=0x49)

# Read encoder position
while True:
    pos = ss.encoder_position
    print("Position:", pos)

With NeoPixel LED

import board
import busio
from adafruit_seesaw.seesaw import Seesaw
from adafruit_seesaw.neopixel import NeoPixel

# Initialize I2C
i2c = busio.I2C(board.SCL, board.SDA)
ss = Seesaw(i2c, addr=0x49)

# Create NeoPixel object
pixel = NeoPixel(ss, 6, brightness=0.3)  # Pin 6 on seesaw

# Color cycling based on position
color_index = 0
colors = [(255, 0, 0), (0, 255, 0), (0, 0, 255)]

while True:
    pos = ss.encoder_position
    print("Position:", pos)
    
    # Update LED color
    pixel.fill(colors[pos % 3])

Interrupt-Based Reading

import board
import busio
import digitalio
from adafruit_seesaw.seesaw import Seesaw

# Initialize I2C
i2c = busio.I2C(board.SCL, board.SDA)
ss = Seesaw(i2c, addr=0x49)

# Enable encoder interrupts
ss.enable_encoder_interrupt()

# Interrupt pin setup
int_pin = digitalio.DigitalInOut(board.D2)
int_pin.direction = digitalio.Direction.INPUT
int_pin.pull = digitalio.Pull.UP

last_position = 0

while True:
    # Check interrupt pin
    if not int_pin.value:  # Active low
        current_position = ss.encoder_position
        if current_position != last_position:
            print("Position:", current_position)
            last_position = current_position

TinyGo Examples

TinyGo support for the Adafruit seesaw library is limited. For TinyGo development, direct I2C register access is recommended.

Direct I2C Register Access (TinyGo)

package main

import (
	"fmt"
	"machine"
	"time"

	"tinygo.org/x/drivers/seesaw"
)

func main() {
	// I2C configuration for XIAO SAMD21/RP2040
	machine.I2C0.Config.SCL = machine.D5
	machine.I2C0.Config.SDA = machine.D4
	
	err := machine.I2C0.Enable()
	if err != nil {
		fmt.Println("I2C init failed:", err)
		return
	}
	
	// Create seesaw driver
	ss := seesaw.New(machine.I2C0)
	ss.Address = 0x49  // Default address
	
	for {
		// Read encoder position (SEESAW_ENCODER_POS = 0x10)
		pos, err := ss.ReadEncoderPosition()
		if err != nil {
			fmt.Println("Read error:", err)
		} else {
			fmt.Printf("Position: %d\n", pos)
		}
		
		time.Sleep(100 * time.Millisecond)
	}
}

Troubleshooting

Common Issues

I2C Address Configuration

The seesaw firmware allows address changes. To scan for devices:

// Arduino I2C scanner
#include <Wire.h>

void setup() {
    Serial.begin(115200);
    Wire.begin();
    
    Serial.println("Scanning for I2C devices...");
    for (byte address = 0x49; address <= 0x51; address++) {
        Wire.beginTransmission(address);
        if (Wire.endTransmission() == 0) {
            Serial.print("Found device at 0x");
            Serial.println(address, HEX);
        }
    }
}

Resetting Seesaw

If the encoder behaves erratically, try resetting:

ss.softwareReset();
ss.begin();  // Reinitialize

Reference Links

• Adafruit Product 4991: https://www.adafruit.com/product/4991
• Adafruit Product 5740: https://www.adafruit.com/product/5740
• Adafruit Seesaw Arduino Library: https://github.com/adafruit/Adafruit_Seesaw
• Adafruit Seesaw Python Library: https://github.com/adafruit/Adafruit_CircuitPython_seesaw
• Seesaw Firmware Documentation: https://cdn-learn.adafruit.com/downloads/pdf/adafruit-seesaw-external-irq-neopixel-no-keypad-external-breakout.pdf