Your first value in the cloud

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Find your MQTT credentials

In the console open Keys & Sub Users. You need the username (your account key) and the MQTT password. The broker address and ports are shown there too.

Open Keys & Sub Users →

Nothing to create — it is already there

demo_device, demo_field_1 and demo_field_2 were created automatically when you registered. You can see them under Devices and Fields.

Devices  ·  Fields

Copy this code into the Arduino IDE

The complete sketch. It publishes a made-up value to demo_field_1 every 3 seconds and listens on demo_field_2 to switch the built-in LED.

#if defined(ESP32)
  #include <WiFi.h>
  #include <WiFiClientSecure.h>
  WiFiClientSecure net;
#else
  #include <ESP8266WiFi.h>
  #include <WiFiClientSecureBearSSL.h>
  BearSSL::WiFiClientSecure net;
#endif
#include <PubSubClient.h>        // install "PubSubClient" by Nick O'Leary

#ifndef LED_BUILTIN
  #define LED_BUILTIN 2          // some ESP32 boards don't define it
#endif

const char* SSID      = "YOUR_WIFI_SSID";
const char* PASSWORD  = "YOUR_WIFI_PASSWORD";
const char* ACCOUNT   = "YOUR_ACCOUNT_KEY";      // MQTT username - Console → Keys & Sub Users
const char* MQTT_PASS = "YOUR_MQTT_PASSWORD";

String pubTopic = String(ACCOUNT) + "/in/device/demo_device/demo_field_1";   // device → cloud
String subTopic = String(ACCOUNT) + "/out/device/demo_device/demo_field_2";  // cloud → device

PubSubClient mqtt(net);

void onMessage(char* topic, byte* payload, unsigned int len) {
    String msg;
    for (unsigned int i = 0; i < len; i++) msg += (char)payload[i];
    bool on = msg.toFloat() > 0.5;
#if defined(ESP8266)
    digitalWrite(LED_BUILTIN, on ? LOW : HIGH);   // ESP8266 LED is inverted
#else
    digitalWrite(LED_BUILTIN, on ? HIGH : LOW);
#endif
    Serial.println("demo_field_2 = " + msg);
}

void setup() {
    Serial.begin(115200);
    pinMode(LED_BUILTIN, OUTPUT);
    WiFi.begin(SSID, PASSWORD);
    while (WiFi.status() != WL_CONNECTED) { delay(500); Serial.print("."); }
    Serial.println("\nWiFi connected");

    net.setInsecure();                             // skip certificate check
    mqtt.setServer("cloud.virtuino.com", 8883);    // TLS
    mqtt.setCallback(onMessage);
}

void loop() {
    if (!mqtt.connected()) {
        String clientId = String(ACCOUNT) + "-" + String(random(0xffff), HEX);
        if (mqtt.connect(clientId.c_str(), ACCOUNT, MQTT_PASS)) mqtt.subscribe(subTopic.c_str());
        else { Serial.println("MQTT failed, retrying..."); delay(2000); return; }
    }
    mqtt.loop();

    static unsigned long last = 0;
    if (millis() - last > 3000) {
        last = millis();
        float sensor_value = 25 + random(-5,+5);
        mqtt.publish(pubTopic.c_str(), String(sensor_value).c_str());
    }
}

Enter your credentials and WiFi details

Replace the four placeholders at the top of the sketch with your own values.

const char* SSID      = "YOUR_WIFI_SSID";
const char* PASSWORD  = "YOUR_WIFI_PASSWORD";
const char* ACCOUNT   = "YOUR_ACCOUNT_KEY";
const char* MQTT_PASS = "YOUR_MQTT_PASSWORD";

Install PubSubClient, then upload

In the Arduino IDE open Sketch → Include Library → Manage Libraries, search for PubSubClient by Nick O'Leary and install it. Then choose your ESP32 or ESP8266 board and the correct serial port, and press Upload.

Open the Serial Monitor at 115200 baud. Once WiFi and MQTT connect, the board starts publishing silently every 3 seconds.

Build the dashboard and switch the LED

Create a dashboard and add two widgets: a value or level widget bound to demo_field_1, and a switch bound to demo_field_2. The value updates every 3 seconds, and the switch turns the board's LED on and off instantly.

Console → Dashboards  ·  Widget guide

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Find your HTTP API key

In the console open Keys & Sub Users and copy your Default Key from the HTTP API Keys panel.

Open Keys & Sub Users →

Nothing to create — it is already there

demo_device and demo_field_1 were created automatically when you registered. You can see them under Devices and Fields.

Devices  ·  Fields

Copy this code into the Arduino IDE

This is the complete sketch. It makes up a value around 25 and sends it every 3 seconds, so you can see data arriving before wiring any sensor.

#if defined(ESP32)
  #include <WiFi.h>          // ESP32
#else
  #include <ESP8266WiFi.h>   // ESP8266
#endif
#include <VirtuinoCloud.h>

const char* SSID     = "YOUR_WIFI_SSID";
const char* PASSWORD = "YOUR_WIFI_PASSWORD";
const char* API_KEY  = "YOUR_API_KEY";    // Console → Keys & Sub Users
const char* DEVICE   = "demo_device";     // must match device name in Console exactly

VirtuinoCloud cloud(API_KEY);

void setup() {
    Serial.begin(115200);
    WiFi.begin(SSID, PASSWORD);
    while (WiFi.status() != WL_CONNECTED) { delay(500); Serial.print("."); }
    Serial.println("\nWiFi connected");
}

void loop() {
    float sensor_value = 25 + random(-5,+5);   // replace with a real sensor read

    bool ok = cloud.write(DEVICE, "demo_field_1", sensor_value);
    Serial.println(ok ? "Uploaded" : "Upload failed — check WiFi and API key");
    delay(3000);   // upload every 3 seconds
}

#include <WiFiNINA.h>       // Uno WiFi Rev2, MKR WiFi 1010, Nano 33 IoT, Nano RP2040
#include <VirtuinoCloud.h>  // also install ArduinoHttpClient from Library Manager

const char* SSID     = "YOUR_WIFI_SSID";
const char* PASSWORD = "YOUR_WIFI_PASSWORD";
const char* API_KEY  = "YOUR_API_KEY";
const char* DEVICE   = "demo_device";

VirtuinoCloud cloud(API_KEY);

void setup() {
    Serial.begin(115200);
    WiFi.begin(SSID, PASSWORD);
    while (WiFi.status() != WL_CONNECTED) { delay(500); Serial.print("."); }
    Serial.println("\nWiFi connected");
}

void loop() {
    float sensor_value = 25 + random(-5,+5);   // replace with a real sensor read

    bool ok = cloud.write(DEVICE, "demo_field_1", sensor_value);
    Serial.println(ok ? "Uploaded" : "Failed");
    delay(3000);
}

Enter your API key and WiFi details

Replace the three placeholders at the top of the sketch with your own values.

const char* SSID     = "YOUR_WIFI_SSID";
const char* PASSWORD = "YOUR_WIFI_PASSWORD";
const char* API_KEY  = "YOUR_API_KEY";

Install the VirtuinoCloud library

In the Arduino IDE open Sketch → Include Library → Manage Libraries, search for VirtuinoCloud and click Install. Install ArduinoJson the same way.

Select your board and upload

Choose the ESP32 or ESP8266 board and the correct serial port, then press Upload. Open the Serial Monitor at 115200 baud — you should see Uploaded every 3 seconds.

Watch the data arrive

Open the console and go to Data → Data Monitor. Select demo_device and demo_field_1 and your values appear.

Open Data Monitor →