This section will cover how to create devices firmware using libraries to easily create data input and output resources, calling endpoints, or streaming data to real-time WebSockets, etc.

Sketch Overview

Almost all Arduino Sketches looks the same. There is a setup method, and there is a loop method. Nothing changes here while integrating with However you must know where you should define your device resources, or where it is possible to interact with external services. In general terms, any device resource (led, relay, sensor, servo, etc.) must be defined inside the setup() method. As well as you initialize your devices, set the input/output direction of a digital pin, or initialize the Serial port speed, you also need to initialize here your resources. This basically consists on configuring what values or resources you want to expose over the Internet.

The loop() is the place to always call to the thing.handle() method, so the thinger libraries can handle the connection with the platform. This is the place also for calling your endpoints, or streaming real-time data to an open WebSocket. Please, take into account to do not add any delay inside the loop() except if you know what you are doing, like working with deep sleep modes or so in your device. Any other delay will condition the proper functioning of Thinger in your device. Also it can be bad to read a sensor value in every loop if the sensor takes too much time to complete a read. This will result in a device with a noticeable lag while attending to our commands.

// add required headers according to your device
#include <SPI.h>
#include <Ethernet.h>
#include <ThingerEthernet.h>
// initialize Thinger instance (type can change depending on your device)
ThingerEthernet thing("username", "deviceId", "deviceCredential");
void setup() {
// initialize your sensors and pins
// initialize wifi (see examples for your device)
// add resources here, like sensors, lights, etc.
void loop() {
// call always the thing handle in the loop and avoid any delay here
// here you can call endpoints
// and also you can stream resources

You can easily start with some available example for your device after you install the client libraries.

It is recommended to start with some of the examples available in the Arduino IDE when you install the libraries

Setting Credentials

All the devices connected to the platform needs to be authenticated against the server. When you create a device in the console you are basically creating a new device identifier and setting a device credential. Therefore, you need to setup this credentials also in your Arduino code so the device can be recognized and associated to your account. This is normally done while initializing the Thinger instance in the code. That is, when you define the thing instance. Replace here your username, deviceId, and deviceCredential with the values you have registered in the cloud.

ThingerWifi thing("username", "deviceId", "deviceCredential");

Adding Resources

In the platform, each device can define several resources. You can think that a resource is anything you can sense or actuate. For example, a typical resource will be a sensor value like temperature or humidity, or a relay that turns on and off a light. This way, you should define the resources you need to expose over the Internet.

All resources must be defined inside the setup() method of the Arduino sketch. This way the resources are configured at the beginning, but can be accessed later as necessary.

There are three different types of resources, which are explained in the following sections.

Input Resources

If you need to control or actuate your IoT device, it is necessary to define an input resource. In this way, an input resource is anything that can provide information to your device. For example, it can be a resource for turning on and off a light or a relay, change a servo position, adjust a device parameter, etc.

To define an input resource it is used the operator << pointing to the resource name, and it uses a C++11 Lambda function to define the function.

The input resource function takes one parameter of type pson that is a variable type that can contain booleans, numbers, floats, strings, or even structured information like in a JSON document.

The following subsections will show how to define different input resources for typical use cases.

Turn on/off a led, a relay, etc

This kind of resources only requires an on/off state so it can be enabled or disabled as required. As the pson type can hold multiple data types, we can think that the pson parameter of the input function is like a boolean.

So, inside the setup function you can place a resource called led (but you can use any other name), of input type (using the operator <<), that takes a reference to a pson parameter. This example will turn on/off the digital pin 10 using a ternary operator over the in parameter.

thing["led"] << [](pson& in){
digitalWrite(10, in ? HIGH : LOW);

Modify a servo position

Modifying a servo position is quite similar to turning on/off a led. In this case, however, it is necessary to use an integer value. As the pson type can hold multiple data types, we can still use the pson type as an integer value.

thing["servo"] << [](pson& in){

Update sketch variables

You can use the input resources also for updating your sketch variables, so you can change your device behaviour dynamically. This is quite useful in some situations where you want to temporary disable an alarm, change the reporting intervals, update an hysteresis value, and so on. In this way, you can define additional resources to change your variables.

float hysteresis = 0; // defined as a global variable
thing["hysteresis"] << [](pson& in){
hysteresis = in;

Pass multiple data

The pson data type can hold not only different data types, but also is fully compatible with JSON documents. So you can use the Pson data type to receive multiple values at the same time. This example will receive two different floats that are stored with the lat and lon keys.

thing["location"] << [](pson& in){
float lat = in["lat"];
float lon = in["lon"];

Show Input Resources State in Dashboards and API

The Dashboards or API works in a way that when you open them, they query the associated resources to correctly print its current state, i.e., the switch is on or off. In this way, when the API or a Dashboard is open, each associated input resource is called, receiving empty data in the call, as there is no intention to control the resource (the pson input will be empty).

So, how the Dashboards or the API knows what is the current state of an input resource? The resource must set its current state in the input parameter, if it is empty, or use the input value if there is one. This way, we can obtain three different things: query the current resource state (without modifying it), modify the current resource state, and obtain the expected input on the resource (this is how the API explorer on the device works).

Therefore, a correct input resource definition that actually allows to display the current state of the resource in a Dashboard or in the API, will be like this example code.

thing["resource"] << [](pson& in){
in = currentState;
currentState = in;

This sample code basically returns the current state (like a boolean, a number, etc) if there is no input control, or use the incoming data to update the current state. This can be easily adapted for controlling a led, while showing its current state in the dashboard once opened or updated.

thing["led"] << [](pson& in){
in = (bool) digitalRead(pin);
digitalWrite(pin, in ? HIGH : LOW);

Note: for controlling a digital pin just use the method explained in the Easier Resources Section.

Output Resources

Output resources should be used in general when you need to sense or read a sensor value, like temperature, humidity, etc. So the output resources are quite useful for extracting information from the device.

To define an output resource it is used the operator >> pointing out of the resource name, and it uses a C++11 Lambda function to define the output function.

The output resource function takes one parameter of pson type that is a variable type that can contain booleans, numbers, floats, strings, or even structured information like in a JSON document.

The following subsections will show how to define different output resources for typical use cases.

Read a sensor value

Defining an output resource is quite similar to defining an input resource, but in this case it is used the operator >>. In the callback function we can fill the out value with any value we want, like in this case the output from a sensor reading.

thing["temperature"] >> [](pson& out){
out = dht.readTemperature();

Read multiple data

In the same way the input resources can receive multiple values at the same time, the output resources can also provide multiple data. This is an example for providing both latitude and longitude from a GPS.

thing["location"] >> [](pson& out){
out["lat"] = gps.getLatitude();
out["lon"] = gps.getLongitude();

Read sketch variables

If your sketch cannot provide a single sensor reading, as it is doing some kind of data integration, an output resource can be used also for reading your sketch variables, where the computed result is updated frequently.

float yaw = 0; // defined as a global variable
thing["yaw"] >> [](pson& out){
out = yaw;

Input/Output Resources

The last resource type is a resource that not only takes an input or an output, but takes both parameters. This is quite useful when you want to read an output that depends on a input, i.e., when you need to provide a changing reference value to a sensor.

This kind of resources are defined with the operator =. In this case the function takes two different pson parameters. One for input data and another one for output data. This example provides an altitude reading using the BMP180 Sensor. It takes the reference altitude as input, and provides the current altitude as output.

thing["altitude"] = [](pson& in, pson& out){
out = bmp.readAltitude(in);

You can also define more complex input/output resources, that takes several input values, to provide also multiple output values, like in this example that takes value1 and value2 to provide the sum and mult values.

thing["in_out"] = [](pson& in, pson& out){
out["sum"] = (long)in["value1"] + (long)in["value2"];
out["mult"] = (long)in["value1"] * (long)in["value2"];

Resources without parameters

It is also possible to define resources that does not require any input nor generates any output. They are just like callbacks that can be executed as you want, for example to reboot the device, or do some required action.

In this case, the resource is defined as a function without any input or output parameters.

thing["resource"] = [](){
// write here your execution code

Easier Resources

The client library also includes some useful syntactic sugar definitions for declaring resources more easily without having to think in input or or output resources. This syntactic sugar features are macros that are expanded automatically to define the resources in the standard way.

The advantage of using this kind of definitions is that your resources will be able to handle state when you query them from the API. For example, if you have a digital pin enabled or disabled, you will be able to see its current state both in the API explorer or in a dashboard.

Control a digital pin

This kind of resources will allow defining a resource for declaring a control over a digital pin, so you can alternate over on/off states, that can be used for controlling a led, a relay, a light, etc.

It is required to define the digital pin as OUTPUT in your setup code, or the resource will not work properly.

thing["relay"] << digitalPin(PIN_NUMBER);
thing["relay"] << invertedDigitalPin(PIN_NUMBER);

Define Output Resources

This kind of resources will allow defining a resource for declaring a read-only resource, like a value obtained from a sensor, or a given variable in our sketch.

In this example we are defining a resource that exposes a sensor reading, like the DHT11 sensor temperature.

thing["temperature"] >> outputValue(dht.readTemperature());

But it is also possible to define a output resource for any global variable in our sketch.

thing["variable"] >> outputValue(myVar);

Modify Sketch Variables

Our sketch usually defines some parameters or variables that are used inside the loop code. This kind of resources are normally used to handle or control the execution behaviour. With this kind of resources we can modify any parameter we want to expose, like a float, an integer, a boolean, etc.

In this example it is possible to remotely modify the boolean sdLogging variable defined as a global variable.

thing["logging"] << inputValue(sdLogging);

It is also possible to define a callback function to know when the variable has changed, so we can perform any other action. For this use case, define the resource as the following to have some code executed when the hysteresisVar changes.

thing["hysteresis"] << inputValue(hysteresisVar, {
// execute some code when the value change
Serial.println("Hystereis changed to: ");

Servo control

It is also possible to define a resource for controlling a servo instance. This way, the defined resource will automatically handle your servo instance, reading its current position, or changing to a new one according to the API interactions.

For defining a servo resource just define and initialize your servo as usual, and then use the declared instance in the resource definition.

thing["servo"] << servo(myServoInstance);

Communication between devices

In, it is possible that devices can communicate between them. There are two possibilities here. One is the communication between devices from the same account, and the other is the communication between devices from different accounts. Here we describe the two different approaches:

Same account communication

For this use case, in which both devices belongs to the same user account, there is an specific method that allows devices to communicate with other devices with low latency and simple codification. this communication can contain data or not (it is possible to make an empty call). lets Suppose that we have two devices: deviceA and deviceB, and we want to communicate both calling from deviceBto an specific deviceA input resource. We can use "thing.call_device(,);" as shown in the example below:

The deviceA defines a resource like in the following example.

thing[“resource_On_A”] = [](){
Serial.println("Someone is calling me!");

deviceB can easily call this resource and send data to it by running the following command.

// be sure to call it at an appropiate rate
thing.call_device("deviceA", "resource_On_A");

On the other hand, if we want to send the message with a pson payload in order to share data between devices. In this case, the deviceA will need to define a resource with some expected input

thing[“resourceOnA”] << [](pson& in){
int val1 = in["anyValue1"];
float val2 = in["anyValue2"];
// Work with the updated parameters here

Then deviceB can call this method providing the appropriated input by defining a pson type that is filled with the same keys used on resourceOnA, as shown in the code below:

// be sure to call it at an appropiate rate
pson data;
data["anyValue1"] = 3;
data["anyValue2"] = 43.1;
thing.call_device("deviceA", "resourceOnA", data);

deviceB can also call this method by providing the information from an defined resource that generates the information, in this case, the call is similar as the previous example, but using the resource as the data source.

thing["resourceName"] >> [](pson& out){
out["anyValue1"] = 3;
out["anyValue2"] = 43.1;
// be sure to call it at an appropiate rate
thing.call_device("deviceA", "resourceOnA", thing["resourceName"]);

Communication between different accounts

If we want to communicate devices from different accounts, we can do that through calling an endpoint of type Device Call. Just register an endpoint of this type in the console, like in the following example.

In this case it is required to define different parameters in the endpoint:

  • Endpoint Identifier: The endpoint id that the device will use for calling the device.

  • Device Owner: The device owner username.

  • Device Identifier: The device id of the other account.

  • Resource Name: The resource on the device to be called.

  • Device Access Token: A device token generated in the other account for granting external access to the device.

Once defined, the device will be able to call the endpoint, as explained in the following section. It basically consists on calling the call_endpointmethod.


Using Endpoints

In, an endpoint is defined as some kind of external resource that can be accessed by the device. With the endpoints feature, devices can easily send emails, SMS, push data to external Web Services, interact with IFTTT, and any general action that can be made by using WebHooks (Calling HTTP/HTTPS URLs).

Calling an endpoint is so easy from the Arduino sketch, as it is only required to call the call_endpoint method over the thing variable.


You can simply call an endpoint to make some action like sending a predefined email, or also call the endpoint with some data, which is specially useful when you are using third party services that consume your devices data.

You should take extra attention while calling resources, and call them at an appropriate rate. Otherwise you can consume easily your available data, receive hundred of emails, or consume your API calls in third-party services.

Calling Endpoints

In this case we will see a simple example to send an email alert based on a temperature value. For this example, we have configured an email endpoint called high_temp_email that contains some warning text about the temperature. For this case we do not want to check the temperature every millisecond, so we are introducing some variables to control the sensing and warning frequency. In this example, the temperature is checked every hour, and if it is above 30ºC, it will call the endpoint called high_temp_email which will send us an email with the predefined text. It is important here to do not add delays inside the loop method, as it will prevent the required execution of the thing.handle() method, so we are using here a non-blocking delay based on the millis() function.

unsigned long lastCheck = 0;
thing.handle(); // required thing handle
unsigned long currentTs = millis();
lastCheck = currentTs;

You can be so creative here and call your endpoints when the presence sensor makes a detection, when your humidity sensor reports that there is no water in your plants, when the location of a device is not as expected, and many other stuff. Other interesting way of using endpoints is by its integration with IFTTT, so you can interact with multiple third-party services!

Sending Data to Endpoints

Sending data to an endpoint (in JSON format) is also quite easy. We need to call also the call_endpoint method, but in this case adding some information based on the pson data format, which will be automatically converted to JSON. For example, if we want to report data to a third party service like, we can create such kind of endpoints in the console. Once configured, we can call the endpoint with our readings, for example with humidity and temperature values from a DHT sensor.

// be careful of sending data at an appropriate rate!
pson data;
data["temperature"] = dht.readTemperature();
data["humidity"] = dht.readHumidity();
thing.call_endpoint("keen_endpoint", data);

You can also send data based on a defined resource, i.e., suppose you have a resource that already serves the temperature and humidity. It is possible to reuse this definition for sending this same data to the endpoint, without having to redefine the sensor reading, like in the following example.

// defined resource in the setup for reading a sensor value
thing["data"] >> (pson& out){
out["temperature"] = dht.readTemperature();
out["humidity"] = dht.readHumidity();
// be careful of sending data at an appropriate rate!
thing.call_endpoint("endpoint", thing["data"]);

Email Type Endpoint Example

This is a simple example, applied to email type endpoint, with custom body

thing["Level"] >> outputValue(actualRelative);
if(actualLevel>UpperLevel && endpointUpperFlag)

Notice that there are a variable that limitates the run of this "if" just once, its important to define any condition or method to warrantee that this kind of enpoint call is executed just once (or at appropiate rate), because it can get a lot of emails generated by the microcontroller across platform.

At endpoint configuration, in the custom body email, must add double brackets "" to invoke the variable sent by the microcontroller, in our example, we used the following body

"The actual level is %"

And receiving an email with the text:

The actual level is 80.34%

Using Data Buckets provides an easy to use and extremely scalable virtual storage system, that allows to store long term device data from device output resources. This information can be used to be plotted in dashboards, or can be exported in different formats for offline processing or third party Data Analysis process.

From Device Resource

It is not necessary to implement specific codification in your device firmware to start storing data in a data bucket, because they will retrieve information from your output resources, just configure your Data Bucket to set the source and sampling interval as it is explained in our Console documentation at:

Streaming Resource Data

It is also possible to let he device stream the information when required, i.e., by raising an event when detected. In this case, we can use the "Update by Device" option while configuring the bucket, and we will use the streaming resource instruction as described here:

Using a previous defined Output Resource, that was called for example ["location"], it could be done like in the following code snippet.

void loop() {
// use your own logic here to determine when to stream/record the resource.

From Write Call

This option will allow setting the bucket in a state that it will not register any information by default, but it will just wait for writing calls, both from the Arduino library using the write_bucket method, as shown here, or calling the REST API directly like done with Sigfox. This feature opens the option to register information in the same bucket from different devices, or store information from devices that are not connected permanently with the server, that are in sleep mode, or use a different technology like Sigfox.

Here is an example of an ESP8266 device writing information to a bucket using the write_bucket function:

void setup() {
// define the resource with temperature and humidity
thing["door_status"] >> [](pson &out){
out["OPEN"] = (bool)digitalRead(SENSOR_PIN);
void loop() {
// handle connection
// write to bucket BucketId when the door changes its status
thing.write_bucket("BucketId", "door_status");

Note that this instruction will retrieve the ["door_status"] resource PSON, so it is also possible to call this function by attaching a custom PSON, as shown down below:

void loop(){
// handle connection
// write to bucket BucketId when the door changes its status
thing.write_bucket("BucketId", "door_status");

Streaming Resources

In you can open WebSockets connections against your devices, so you can receive sensor values, events, or any other information in real-time. The WebSockets are mainly used in the Dashboard feature of the Console, and are normally used for streaming resources at a fixed configurable interval. This functionality is available right out of the box when you define an output resource. However, if you want to transmit the information right when it is required, like when your device detects a movement, presence, etc., you must program some code, that is quite similar to calling an endpoint.

In this case, you must detect when you want to stream the event, like the accelerometer value is over some threshold, your presence sensor is making a detection, or the compass heading is changing. This is up to you when it is necessary to stream new data. Streaming resources also requires that another endpoint is connected listening for them (i.e., from a WebSocket connection), so if there is no one listening for this data, the data is not sent. This is handled automatically by the client library and the server, therefore it is safe to stream data always, as the device will transmit the information only when there is a destination.

The following example will report the compass heading in real-time if the heading value changes more than 1 degree.

void setup(){
thing["heading"] >> [](pson& out){
out = getHeading();
float previousHeading = 0;
void loop() {
float currentHeading = getHeading();

Enabling Debug Output library provides extensive logging of its activities, which is especially useful when one needs to troubleshoot authentication and Wi-Fi connectivity issues. Include the following definition in your sketch, but make sure it comes first, before any other includes (it was reported to cause crashes on some boards otherwise).

#define _DEBUG_
// the rest of your sketch goes here

It is also necessary to enable Serial communication, as all the debugging information is displayed over Serial. So enable it in your sketch in the setup method.

void setup() {

ESP8266 Deep Sleep and SmartConfig

SmartConfig allows one to configure board's WiFi credentials via an external device on the same network (e.g. smartphone or another wifi client). This means no sensitive information goes into a sketch nor in a config file on a device.

Deep Sleep is a special mode of ESP8266 which allows it to shut down most of the circuits and wake up after some configurable time. For deep sleep (and wake up) to work properly, one has to connect GPIO16 (usually a D0 on dev boards) and RST pins.

However, some boards chose to wire a built-in LED to the same D0 pin, and will go into a crash loop when using ThingerSmartConfig class, which uses the LED as a debugging aid at runtime. The solution is to use an overloaded constructor and disable its use of the LED.

ThingerSmartConfig thing(USERNAME,
false); // required for deep sleep

Connection Troubleshooting Guideline

There are few situations that can produce the malfunction of the software client, hampering the connection with the IoT platform or making it unstable. But software client has been provided of some tools to detect and avoid these kind of problems.

If a recently programmed device is showing problems to be "online" on Server or even is being locked, the "_DEBUG_" command can help identify the problem. This command must be included at the top of the program, along with the required instructions for printing in the system console or serial port, for example, in Arduino framework:

When this command is included, the program will print all the communication traze, allowing to identify any mistake that can be the cause of the problem.

next list shows the main problems and fix for each one