Before you get started using Adafruit IO with your Arduino, you'll need to select a library. We provide and support both the Adafruit IO and Adafruit MQTT libraries listed below, but try starting with the Adafruit IO Arduino Library below:

Adafruit IO Arduino Library

The library supports the following network platforms and hardware: 

• Adafruit AirLift
• ESP8266
• ESP32
• ATWINC1500
• WICED
• Ethernet
• FONA (Cellular)

Installation

You can install the library through the Arduino Library Manager (click: Sketch -> Include Library -> Manage Libraries...)

Alternatively, you can download the Adafruit IO Arduino Library from GitHub and install it manually.

Usage

The included examples sketches will walk you through all of the features of the library. They can be used on all platforms, but they default to WiFi. Most of the sketches have companion projects on the Adafruit Learning system.

To change between platforms, you will need to change two lines of code in the config.h tab of the example. It is recommended that you start with one of the Adafruit WiFi feathers before moving on to cellular or ethernet.

For all examples, you will need to set IO_USERNAME and IO_KEY in the config.h tab:

To find your IO_USERNAME, navigate to your profile on Adafruit IO and click View AIO Key. Copy the Username field (ctrl+c or command+c)

Then, in the config.h tab, replace the "your_username" text with your the username from your profile:

To find your IO_Key, navigate to your profile, click View AIO Key, and copy the ACTIVE KEY field to your clipboard (ctrl+c or command+c).

In config.h, replace the IO_KEY with the IO Key copied to your clipboard.

Using the Adafruit IO Arduino Library with WiFi

If you are using the included examples, you do not need to change anything for the Adafruit WiFi Feathers. All WiFi based Feathers (ESP8266, M0 WiFi, WICED) will work with the examples out of the box once you add your WiFi SSID and Password to the config.h file. 

In the config.h tab, replace "your_ssid" with your WiFi's SSID and "your_pass" with your WiFi's password:

Using the Adafruit IO Arduino Library with Ethernet

For Ethernet, you will only need to change from the default WiFi constructor to the Ethernet specific constructor in the config.h tab. The rest of the sketch remains the same.

You will need to comment out these WiFi lines in config.h:

#include "AdafruitIO_WiFi.h"
AdafruitIO_WiFi io(IO_USERNAME, IO_KEY, WIFI_SSID, WIFI_PASS);

and uncomment the Ethernet lines in config.h:

#include "AdafruitIO_Ethernet.h"
AdafruitIO_Ethernet io(IO_USERNAME, IO_KEY);

Using the Adafruit IO Arduino Library with Cellular (32u4 FONA)

For FONA, you will only need to change from the default WiFi constructor to the FONA specific constructor in the config.h tab. The rest of the sketch remains the same.

You will need to comment out these WiFi lines in config.h:

#include "AdafruitIO_WiFi.h"
AdafruitIO_WiFi io(IO_USERNAME, IO_KEY, WIFI_SSID, WIFI_PASS);

and uncomment the FONA lines in config.h:

#include "AdafruitIO_FONA.h"
AdafruitIO_FONA io(IO_USERNAME, IO_KEY);

If your carrier requires APN info, you can set it by adding a call to io.setAPN() after io.connect() in the setup()function of the sketch.

void setup() {
  // start the serial connection
  Serial.begin(115200);
  // connect to io.adafruit.com
  io.connect();
  io.setAPN(F("your_apn"), F("your_apn_user"), F("your_apn_pass"));
}

Adafruit MQTT Arduino Library  

We also have a library to provide support for accessing Adafruit IO using MQTT. This is a general-purpose MQTT library for Arduino that's built to use as few resources as possible so that it can work with platforms like the Arduino Uno.  Unfortunately platforms like the Trinket 3.3V or 5V (based on the ATtiny85) have too little program memory to use the library--stick with a Metro 328p or better!

The MQTT library supports the following network platforms and hardware:

• Adafruit CC3000
• Adafruit FONA
• ESP8266 
• Generic Arduino Client Interface (incl. ethernet shield and similar networking hardware)

Installation

You can install the library through the Arduino Library Manager (click: Sketch -> Include Library -> Manage Libraries...)

Alternatively, you can download the MQTT library from GitHub and manually install it.

If you're using an Adafruit FONA, you'll need to install an additional two libraries for the MQTT Library to work properly:

• Adafruit SleepyDog, watchdog library used by FONA code for reliability.

• Adafruit FONA, required for the FONA hardware.