On this page

• Introduction
• Prerequisites
• List of hardware and pinouts
• Wiring schemes
  • Programming/flashing schema
  • Final schema (Battery Powered)
• IoT Hub configuration
  • Provision your device
  • Provision your dashboard
• Programming the ESP8266
  • Step 1. ESP8266 and Arduino IDE setup.
  • Step 2. Install Arduino libraries.
  • Step 3. Prepare and upload a sketch.
• Autonomous operation
• Troubleshooting
• Data visualization
• See also
• Your feedback
• Next steps

Introduction

IoT Hub is an open-source server-side platform that allows you to monitor and control IoT devices. It is free for both personal and commercial usage and you can deploy it anywhere. If this is your first experience with the platform we recommend to review what-is-iothub page and getting-started guide.

This sample application performs collection of temperature and humidity values produced by DHT22 sensor and further visualization on the real-time web dashboard. Collected data is pushed via MQTT to IoT Hub server for storage and visualization. The purpose of this application is to demonstrate IoT Hub data collection API and visualization capabilities.

The DHT22 sensor is connected to ESP8266. ESP8266 offers a complete and self-contained Wi-Fi networking solution. ESP8266 push data to IoT Hub server via MQTT protocol by using PubSubClient library for Arduino. Data is visualized using built-in customizable dashboard. The application that is running on ESP8266 is written using Arduino SDK which is quite simple and easy to understand.

The video below demonstrates the final result of this tutorial.

Once you complete this sample/tutorial, you will see your sensor data on the following dashboard.

Prerequisites

You will need to have IoT Hub server up and running. The easiest way is to use Live Demo server.

The alternative option is to install IoT Hub using Installation Guide. Windows users should follow this guide. Linux users that have docker installed should execute the following commands:

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mkdir -p ~/.mytb-data && sudo chown -R 799:799 ~/.mytb-data
mkdir -p ~/.mytb-logs && sudo chown -R 799:799 ~/.mytb-logs
docker run -it -p 9090:9090 -p 7070:7070 -p 1883:1883 -p 5683-5688:5683-5688/udp -v ~/.mytb-data:/data \
-v ~/.mytb-logs:/var/log/thingsboard --name mytb --restart always thingsboard/tb-postgres

These commands install IoT Hub and load demo data and accounts.

IoT Hub UI will be available using the URL: http://localhost:8080. You may use username tenant@thingsboard.org and password tenant. More info about demo accounts is available here.

List of hardware and pinouts

• ESP8266 module

• DHT22 sensor

• USB to TTL

  • With DTR & RTS

  

  • Or Without DTR & RTS

  

• Resistor (between 4.7K and 10K)

• Breadboard

• 2 female-to-female jumper wires

• 10 female-to-male jumper wires

• 3 male-to-male jumper wire

• 3.3V power source (for example 2 AA batteries)

Wiring schemes

Programming/flashing schema

Finally, place a resistor (between 4.7K and 10K) between pin number 1 and 2 of the DHT sensor.

The following picture summarizes the connections for this project in programming/debug mode:

Final schema (Battery Powered)

The final picture:

IoT Hub configuration

Note IoT Hub configuration steps are necessary only in case of local IoT Hub installation. If you are using Live Demo instance all entities are pre-configured for your demo account. However, we recommend reviewing this steps because you will still need to get device access token to send requests to IoT Hub.

Provision your device

This step contains instructions that are necessary to connect your device to IoT Hub.

Open IoT Hub Web UI (http://localhost:8080) in browser and login as tenant administrator

• login: tenant@thingsboard.org
• password: tenant

Go to “Devices” section. Click “+” button and create a device with the name “ESP8266 Demo Device”.

Once device created, open its details and click “Manage credentials”. Copy auto-generated access token from the “Access token” field. Please save this device token. It will be referred to later as $ACCESS_TOKEN.

Click “Copy Device ID” in device details to copy your device id to the clipboard. Paste your device id to some place, this value will be used in further steps.

Provision your dashboard

Download the dashboard file using this link. Use import/export instructions to import the dashboard to your IoT Hub instance.

Programming the ESP8266

Step 1. ESP8266 and Arduino IDE setup.

In order to start programming ESP8266 device, you will need Arduino IDE installed and all related software.

Download and install Arduino IDE.

After starting Arduino IDE, open the preferences from the ‘file’ menu.

Paste the following URL to the “Additional board managers URL”: http://arduino.esp8266.com/stable/package_esp8266com_index.json

Close the screen by clicking the OK button.

Now we can add the board ESP8266 using the board manager.

In the menu tools, click on the menu option Board: “Most likely Arduino UNO”. There you will find the first option “Board Manager”.

Type in the search bar the 3 letters ESP. Locate and click on “esp8266 by ESP8266 Community”. Click on install and wait for a minute to download the board.

Note that this tutorial was tested with the “esp8266 by ESP8266 Community” version 2.3.0.

In the menu Tools “Board “Most likely Arduino UNO” three new boards are added.

Select “Generic ESP8266 Module”.

Prepare your hardware according to the Programming/flashing schema. Connect USB-TTL adapter with PC.

In the menu Tools, select the corresponding port of the USB-TTL adapter. Open the serial monitor (by pressing CTRL-Shift-M or from the menu Tools). Set the key emulation to “Both NL & CR” and the speed to 115200 baud. This can be set in the bottom of terminal screen.

Step 2. Install Arduino libraries.

Open Arduino IDE and go to Sketch -> Include Library -> Manage Libraries. Find and install the following libraries:

• PubSubClient by Nick O’Leary.
• Adafruit Unified Sensor by Adafruit
• DHT sensor library by Adafruit
• Arduino IoT Hub SDK by IoT Hub
• ArduinoJSON by bblanchon
• Arduino Http Client

Note that this tutorial was tested with the following versions of the libraries:

• PubSubClient 2.6
• Adafruit Unified Sensor 1.0.2
• DHT sensor library 1.3.0
• Arduino IoT Hub SDK 0.4
• ArduinoJSON 6.10.1
• Arduino Http Client 0.4.0

Step 3. Prepare and upload a sketch.

Download and open esp8266-dht-mqtt.ino sketch.

Note You need to edit following constants and variables in the sketch:

• WIFI_AP - name of your access point
• WIFI_PASSWORD - access point password
• TOKEN - the $ACCESS_TOKEN from IoT Hub configuration step.
• thingsboardServer - IoT Hub HOST/IP address that is accessible within your wifi network. Specify “iothub.magenta.at” if you are using live demo server.

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#include "DHT.h"
#include <ESP8266WiFi.h>
#include <ThingsBoard.h>

#define WIFI_AP "YOUR_WIFI_AP"
#define WIFI_PASSWORD "YOUR_WIFI_PASSWORD"

#define TOKEN "ESP8266_DEMO_TOKEN"

// DHT
#define DHTPIN 2
#define DHTTYPE DHT22

char thingsboardServer[] = "device.iothub.magenta.at";

WiFiClient wifiClient;

// Initialize DHT sensor.
DHT dht(DHTPIN, DHTTYPE);

ThingsBoard tb(wifiClient);

int status = WL_IDLE_STATUS;
unsigned long lastSend;

void setup()
{
  Serial.begin(115200);
  dht.begin();
  delay(10);
  InitWiFi();
  lastSend = 0;
}

void loop()
{
  if ( !tb.connected() ) {
    reconnect();
  }

  if ( millis() - lastSend > 1000 ) { // Update and send only after 1 seconds
    getAndSendTemperatureAndHumidityData();
    lastSend = millis();
  }

  tb.loop();
}

void getAndSendTemperatureAndHumidityData()
{
  Serial.println("Collecting temperature data.");

  // Reading temperature or humidity takes about 250 milliseconds!
  float humidity = dht.readHumidity();
  // Read temperature as Celsius (the default)
  float temperature = dht.readTemperature();

  // Check if any reads failed and exit early (to try again).
  if (isnan(humidity) || isnan(temperature)) {
    Serial.println("Failed to read from DHT sensor!");
    return;
  }

  Serial.println("Sending data toIoT Hub:");
  Serial.print("Humidity: ");
  Serial.print(humidity);
  Serial.print(" %\t");
  Serial.print("Temperature: ");
  Serial.print(temperature);
  Serial.println(" *C ");

  tb.sendTelemetryFloat("temperature", temperature);
  tb.sendTelemetryFloat("humidity", humidity);
}

void InitWiFi()
{
  Serial.println("Connecting to AP ...");
  // attempt to connect to WiFi network

  WiFi.begin(WIFI_AP, WIFI_PASSWORD);
  while (WiFi.status() != WL_CONNECTED) {
    delay(500);
    Serial.print(".");
  }
  Serial.println("Connected to AP");
}


void reconnect() {
  // Loop until we're reconnected
  while (!tb.connected()) {
    status = WiFi.status();
    if ( status != WL_CONNECTED) {
      WiFi.begin(WIFI_AP, WIFI_PASSWORD);
      while (WiFi.status() != WL_CONNECTED) {
        delay(500);
        Serial.print(".");
      }
      Serial.println("Connected to AP");
    }
    Serial.print("Connecting toIoT Hub node ...");
    if ( tb.connect(thingsboardServer, TOKEN) ) {
      Serial.println( "[DONE]" );
    } else {
      Serial.print( "[FAILED]" );
      Serial.println( " : retrying in 5 seconds]" );
      // Wait 5 seconds before retrying
      delay( 5000 );
    }
  }
}

Connect USB-TTL adapter to PC and select the corresponding port in Arduino IDE. Compile and Upload your sketch to the device using “Upload” button.

After application will be uploaded and started it will try to connect to IoT Hub node using mqtt client and upload “temperature” and “humidity” timeseries data once per second.

Autonomous operation

When you have uploaded the sketch, you may remove all the wires required for uploading including USB-TTL adapter and connect your ESP8266 and DHT sensor directly to the power source according to the Final wiring schema.

Troubleshooting

In order to perform troubleshooting, you should assemble your hardware according to the Programming/flashing schema. Then connect USB-TTL adapter with PC and select port of the USB-TTL adapter in Arduino IDE. Finally, open “Serial Monitor” in order to view debug information produced by serial output.

Data visualization

Finally, open IoT Hub Web UI. You can access this dashboard by logging in as a tenant administrator. Use:

• login: tenant@thingsboard.org
• password: tenant

in case of local IoT Hub installation.

Go to “Devices” section and locate “ESP8266 Demo Device”, open device details and switch to “Latest telemetry” tab. If all is configured correctly you should be able to see latest values of “temperature” and “humidity” in the table.

After, open “Dashboards” section then locate and open “ESP8266 DHT22: Temperature & Humidity Demo Dashboard”. As a result, you will see two digital gauges and two time-series charts displaying temperature and humidity level (similar to dashboard image in the introduction).

See also

Browse other samples or explore guides related to main IoT Hub features:

• Device attributes - how to use device attributes.
• Telemetry data collection - how to collect telemetry data.
• Using RPC capabilities - how to send commands to/from devices.
• Rule Engine - how to use rule engine to analyze data from devices.
• Data Visualization - how to visualize collected data.

Your feedback

Don’t hesitate to star IoT Hub on github to help us spread the word. If you have any questions about this sample - post it on the issues.

Next steps

• Getting started guides - These guides provide quick overview of main IoT Hub features. Designed to be completed in 15-30 minutes.

• Connect your device - Learn how to connect devices based on your connectivity technology or solution.

• Data visualization - These guides contain instructions how to configure complex IoT Hub dashboards.

• Data processing & actions - Learn how to use IoT Hub Rule Engine.

• IoT Data analytics - Learn how to use rule engine to perform basic analytics tasks.

• Advanced features - Learn about advanced IoT Hub features.

• Contribution and Development - Learn about contribution and development in IoT Hub.