![\"ESP32](\"https:\/\/i0.wp.com\/randomnerdtutorials.com\/wp-content\/uploads\/2020\/04\/ESP32-DHT11-DHT22-Temperature-Humidity-Sensor-MQTT-Publish-Arduino-IDE-Node-RED.jpg?resize=1200%2C675&quality=100&strip=all&ssl=1\")
<\/figure><\/div>\n\n\nRecommended reading:<\/strong> What is MQTT and How It Works<\/a><\/p>\n\n\n\n The following diagram shows a high-level overview of the project we’ll build.<\/p>\n\n\n Before proceeding with this tutorial, make sure you check the following prerequisites.<\/p>\n\n\n\n We’ll program the ESP32 using Arduino IDE, so make sure you have the ESP32 add-on installed.<\/p>\n\n\n\n To use MQTT, you need a broker. We\u2019ll be using Mosquitto broker<\/a> installed on a Raspberry Pi. Read How to Install Mosquitto Broker on Raspberry Pi<\/a>.<\/p>\n\n\n\n You can use any other MQTT broker, including a cloud MQTT broker. We’ll show you how to do that in the code later on.<\/p>\n\n\n\n If you\u2019re not familiar with MQTT make sure you read our introductory tutorial: What is MQTT and How It Works<\/a>.<\/p>\n\n\n\n To use MQTT with the ESP32 we’ll use the Async MQTT Client Library<\/a>.<\/p>\n\n\n\n Installing the Async MQTT Client Library<\/strong><\/p>\n\n\n\n Alternatively, you can go to Sketch <\/strong>> Include Library<\/strong> > Add . ZIP<\/strong> library and select the library you’ve just downloaded.<\/p>\n\n\n\n Installing the Async TCP Library<\/strong><\/p>\n\n\n\n To use MQTT with the ESP, you also need the Async TCP library<\/a>.<\/p>\n\n\n\n Alternatively, you can go to Sketch <\/strong>> Include Library<\/strong> > Add . ZIP<\/strong> library and select the library you’ve just downloaded. <\/p>\n\n\n\n To read from the DHT sensor, we\u2019ll use the DHT library from Adafruit<\/a>. To use this library you also need to install the Adafruit Unified Sensor library<\/a>. Follow the next steps to install those libraries.<\/p>\n\n\n\n 1. Open your Arduino IDE and go to Sketch <\/strong>> Include Library<\/strong> > Manage Libraries<\/strong>. The Library Manager should open.<\/p>\n\n\n\n 2. Search for \u201cDHT<\/strong>\u201d on the Search box and install the DHT library from Adafruit.<\/p>\n\n\n 3. After installing the DHT library from Adafruit, type \u201cAdafruit Unified Sensor<\/strong>\u201d in the search box. Scroll all the way down to find the library and install it.<\/p>\n\n\n After installing the libraries, restart your Arduino IDE.<\/p>\n\n\n\n To learn more about the DHT11 or DHT22 temperature sensor, read our guide: ESP32 with DHT11\/DHT22 Temperature and Humidity Sensor using Arduino IDE<\/a><\/p>\n\n\n\n For this tutorial you need the following parts:<\/p>\n\n\n\n You can use the preceding links or go directly to MakerAdvisor.com\/tools<\/a> to find all the parts for your projects at the best price!<\/p> Wire the DHT11 or DHT22 to the ESP32 as shown in the following schematic diagram with the data pin connected to GPIO 4<\/span>.<\/p>\n\n\n Note: <\/strong> if you have a DHT sensor in a breakout board, it comes with only three pins and with an internal pull-up resistor on pin 2, so you don’t need to connect the resistor. You just need to wire VCC, data and GND. <\/p>\n\n\n\n In this example, we\u2019re connecting the DHT data pin to GPIO 4<\/span>. However, you can use any other suitable digital pin.<\/p>\n\n\n\n Learn how to use the ESP32 GPIOs with our guide: ESP32 Pinout Reference: Which GPIO pins should you use?<\/a><\/p>\n\n\n\n Copy the following code to your Arduino IDE. To make it work for you, you need to insert your network credentials as well as the MQTT broker details.<\/p>\n\n\n View raw code<\/a><\/p>\n\n\n\n The following section imports all the required libraries.<\/p>\n\n\n\n Include your network credentials on the following lines.<\/p>\n\n\n\n Insert the Raspberry Pi IP address, so that the ESP32 connects to your broker.<\/p>\n\n\n\n If you’re using a cloud MQTT broker, insert the broker domain name, for example:<\/p>\n\n\n\n Define the MQTT port.<\/p>\n\n\n\n The temperature and humidity will be published on the following topics:<\/p>\n\n\n\n Define the GPIO that the DHT sensor data pin is connected to. In our case, it is connected to GPIO 4<\/span>.<\/p>\n\n\n\n Uncomment the DHT sensor type you’re using. In our example, we’re using the DHT22.<\/p>\n\n\n\n Initialize the DHT sensor on the pin and type defined earlier.<\/p>\n\n\n\n The temp<\/span> and hum<\/span> variables will hold the temperature and humidity values from the DHT22 sensor.<\/p>\n\n\n\n Create an AsyncMqttClient<\/span> object called mqttClient<\/span> to handle the MQTT client and timers to reconnect to your MQTT broker and router when it disconnects.<\/p>\n\n\n\n Then, create some auxiliary timer variables to publish the readings every 10 seconds. You can change the delay time on the interval<\/span> variable.<\/p>\n\n\n\n Note: <\/strong> the DHT11 and DHT22 have a low sampling rate. You can only request DHT11 readings every second, or every two seconds for the DHT22.<\/p>\n\n\n\n We haven\u2019t added any comments to the functions defined in the next code section. Those functions come with the Async Mqtt Client library. The function\u2019s names are pretty self-explanatory.<\/p>\n\n\n\n For example, the connectToWifi()<\/span> connects your ESP32 to your router:<\/p>\n\n\n\n The connectToMqtt()<\/span> connects your ESP32 to your MQTT broker:<\/p>\n\n\n\n The WiFiEvent()<\/span> function is responsible for handling the Wi-Fi events. For example, after a successful connection with the router and MQTT broker, it prints the ESP32 IP address. On the other hand, if the connection is lost, it starts a timer and tries to reconnect.<\/p>\n\n\n\n The onMqttConnect()<\/span> function runs after starting a session with the broker.<\/p>\n\n\n\n If the ESP32 loses connection with the MQTT broker, it calls the onMqttDisconnect<\/span> function that prints that message in the serial monitor.<\/p>\n\n\n\n When you publish a message to an MQTT topic, the onMqttPublish()<\/span> function is called. It prints the packet id in the Serial Monitor.<\/p>\n\n\n\n Basically, all these functions that we\u2019ve just mentioned are callback functions. So, they are executed asynchronously.<\/p>\n\n\n\n Now, let\u2019s proceed to the setup()<\/span>. Initialize the DHT sensor.<\/p>\n\n\n\n The next two lines create timers that will allow both the MQTT broker and Wi-Fi connection to reconnect, in case the connection is lost.<\/p>\n\n\n\n The following line assigns a callback function, so when the ESP32 connects to your Wi-Fi, it will execute the WiFiEvent()<\/span> function to print the details described earlier.<\/p>\n\n\n\n Finally, assign all the callback functions. This means that these functions will be executed automatically when needed. For example, when the ESP32 connects to the broker, it automatically calls the onMqttConnect()<\/span> function, and so on.<\/p>\n\n\n\n If your broker requires authentication, uncomment the following line and insert your credentials (username and password).<\/p>\n\n\n\n Finally, connect to Wi-Fi.<\/p>\n\n\n\n In the loop()<\/span>, you create a timer that will allow you to get new temperature and humidity readings from the DHT sensor and publishing them on the corresponding topic every 10 seconds.<\/p>\n\n\n\n Learn more about getting readings from the DHT11 or DHT22 sensors: ESP32 with DHT11\/DHT22 Temperature and Humidity Sensor using Arduino IDE<\/a>.<\/p>\n\n\n\n To publish the readings on the corresponding MQTT topics, use the next lines:<\/p>\n\n\n\n Basically, use the publish()<\/span> method on the mqttClient<\/span> object to publish data on a topic. The publish()<\/span> method accepts the following arguments, in order:<\/p>\n\n\n\n The QoS (quality of service) is a way to guarantee that the message is delivered. It can be one of the following levels:<\/p>\n\n\n\n With your Raspberry Pi powered on and running the Mosquitto MQTT broker, upload the code to your ESP32.<\/p>\n\n\n\n Open the Serial Monitor at a baud rate of 115200 and you’ll see that the ESP32 starts publishing messages on the topics we’ve defined previously.<\/p>\n\n\n The ESP32 is publishing temperature readings every 10 seconds on the esp32\/dht\/temperature<\/strong> and esp32\/dht\/humidity<\/strong> topics. Now, you can use any dashboard that supports MQTT or any other device that supports MQTT to subscribe to those topics and receive the readings.<\/p>\n\n\n\n As an example, we’ll create a simple flow using Node-RED to subscribe to those topics and display the readings on gauges.<\/p>\n\n\n\n If you don’t have Node-RED installed, follow the next tutorials:<\/p>\n\n\n\n Having Node-RED running on your Raspberry Pi, go to your Raspberry Pi IP address followed by :1880.<\/p>\n\n\n\n The Node-RED interface should open. Drag two MQTT in nodes, and two gauge nodes to the flow.<\/p>\n\n\n Click the MQTT node and edit its properties.<\/p>\n\n\n The Server field refers to the MQTT broker. In our case, the MQTT broker is the Raspberry Pi, so it is set to localhost:1883. If you’re using a Cloud MQTT broker, you should change that field. <\/p>\n\n\n\n Insert the topic you want to be subscribed to and the QoS. This previous MQTT node is subscribed to the esp32\/dht\/temperature<\/strong> topic. <\/p>\n\n\n\n Click on the other MQTT in node and edit its properties with the same server, but for the other topic: esp32\/dht\/humidity<\/strong>. <\/p>\n\n\n\n Click on the gauge nodes and edit its properties for each reading. The following node is set for the temperature readings. Edit the other chart node for the humidity readings.<\/p>\n\n\n Wire your nodes as shown below:<\/p>\n\n\n Finally, deploy your flow (press the button on the upper right corner).<\/p>\n\n\n Alternatively, you can go to Menu <\/strong>> Import <\/strong>and copy the following to your Clipboard<\/strong> to create your Node-RED flow.<\/p>\n\n\nProject Overview<\/h2>\n\n\n\n
![\"DHT11\/DHT22](\"https:\/\/i0.wp.com\/randomnerdtutorials.com\/wp-content\/uploads\/2020\/04\/ESP32-MQTT-DHT11-DHT22-Node-RED.png?resize=888%2C586&quality=100&strip=all&ssl=1\")
<\/a><\/figure><\/div>\n\n\n\n
Prerequisites<\/h2>\n\n\n\n
Arduino IDE<\/h3>\n\n\n\n
\n
MQTT Broker<\/h3>\n\n\n
![\"Installing](\"https:\/\/i0.wp.com\/randomnerdtutorials.com\/wp-content\/uploads\/2017\/01\/mosquitto-broker.png?resize=200%2C197&quality=100&strip=all&ssl=1\")
<\/figure><\/div>\n\n\nMQTT Libraries<\/h3>\n\n\n\n
\n
async-mqtt-client-master<\/strong><\/del>\u00a0to\u00a0async_mqtt_client<\/strong><\/li>\n\n\n\n\n
AsyncTCP-master<\/strong><\/del>\u00a0to\u00a0AsyncTCP<\/strong><\/li>\n\n\n\nDHT Sensor Libraries<\/h3>\n\n\n\n
![\"Installing](\"https:\/\/i0.wp.com\/randomnerdtutorials.com\/wp-content\/uploads\/2019\/04\/adafruit_dht_library.png?resize=750%2C422&quality=100&strip=all&ssl=1\")
<\/figure><\/div>\n\n\n![\"Installing](\"https:\/\/i0.wp.com\/randomnerdtutorials.com\/wp-content\/uploads\/2019\/04\/adafruit_unified_sensor_library.png?resize=750%2C422&quality=100&strip=all&ssl=1\")
<\/figure><\/div>\n\n\nParts Required<\/h3>\n\n\n\n
\n
![](\"https:\/\/i0.wp.com\/randomnerdtutorials.com\/wp-content\/uploads\/2017\/10\/header-200.png?w=1200&quality=100&strip=all&ssl=1\")
<\/a><\/p>\n\n\n\nSchematic Diagram<\/h2>\n\n\n\n
![\"DHT11](\"https:\/\/i0.wp.com\/randomnerdtutorials.com\/wp-content\/uploads\/2019\/04\/dht_esp32_bb.png?resize=714%2C892&quality=100&strip=all&ssl=1\")
<\/figure><\/div>\n\n\nCode<\/h2>\n\n\n\n
\/*\n Rui Santos & Sara Santos - Random Nerd Tutorials\n Complete project details at https:\/\/RandomNerdTutorials.com\/esp32-mqtt-publish-dht11-dht22-arduino\/\n Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files.\n The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.\n*\/\n#include "DHT.h"\n#include <WiFi.h>\nextern "C" {\n #include "freertos\/FreeRTOS.h"\n #include "freertos\/timers.h"\n}\n#include <AsyncMqttClient.h>\n\n#define WIFI_SSID "REPLACE_WITH_YOUR_SSID"\n#define WIFI_PASSWORD "REPLACE_WITH_YOUR_PASSWORD"\n\n\/\/ Raspberry Pi Mosquitto MQTT Broker\n#define MQTT_HOST IPAddress(192, 168, 1, XXX)\n\/\/ For a cloud MQTT broker, type the domain name\n\/\/#define MQTT_HOST "example.com"\n#define MQTT_PORT 1883\n\n\/\/ Temperature MQTT Topics\n#define MQTT_PUB_TEMP "esp32\/dht\/temperature"\n#define MQTT_PUB_HUM "esp32\/dht\/humidity"\n\n\/\/ Digital pin connected to the DHT sensor\n#define DHTPIN 4 \n\n\/\/ Uncomment whatever DHT sensor type you're using\n\/\/#define DHTTYPE DHT11 \/\/ DHT 11\n#define DHTTYPE DHT22 \/\/ DHT 22 (AM2302), AM2321\n\/\/#define DHTTYPE DHT21 \/\/ DHT 21 (AM2301) \n\n\/\/ Initialize DHT sensor\nDHT dht(DHTPIN, DHTTYPE);\n\n\/\/ Variables to hold sensor readings\nfloat temp;\nfloat hum;\n\nAsyncMqttClient mqttClient;\nTimerHandle_t mqttReconnectTimer;\nTimerHandle_t wifiReconnectTimer;\n\nunsigned long previousMillis = 0; \/\/ Stores last time temperature was published\nconst long interval = 10000; \/\/ Interval at which to publish sensor readings\n\nvoid connectToWifi() {\n Serial.println("Connecting to Wi-Fi...");\n WiFi.begin(WIFI_SSID, WIFI_PASSWORD);\n}\n\nvoid connectToMqtt() {\n Serial.println("Connecting to MQTT...");\n mqttClient.connect();\n}\n\nvoid WiFiEvent(WiFiEvent_t event) {\n Serial.printf("[WiFi-event] event: %d\\n", event);\n switch(event) {\n case ARDUINO_EVENT_WIFI_STA_GOT_IP:\n Serial.println("WiFi connected");\n Serial.println("IP address: ");\n Serial.println(WiFi.localIP());\n connectToMqtt();\n break;\n case ARDUINO_EVENT_WIFI_STA_DISCONNECTED:\n Serial.println("WiFi lost connection");\n xTimerStop(mqttReconnectTimer, 0); \/\/ ensure we don't reconnect to MQTT while reconnecting to Wi-Fi\n xTimerStart(wifiReconnectTimer, 0);\n break;\n }\n}\n\nvoid onMqttConnect(bool sessionPresent) {\n Serial.println("Connected to MQTT.");\n Serial.print("Session present: ");\n Serial.println(sessionPresent);\n}\n\nvoid onMqttDisconnect(AsyncMqttClientDisconnectReason reason) {\n Serial.println("Disconnected from MQTT.");\n if (WiFi.isConnected()) {\n xTimerStart(mqttReconnectTimer, 0);\n }\n}\n\n\/*void onMqttSubscribe(uint16_t packetId, uint8_t qos) {\n Serial.println("Subscribe acknowledged.");\n Serial.print(" packetId: ");\n Serial.println(packetId);\n Serial.print(" qos: ");\n Serial.println(qos);\n}\nvoid onMqttUnsubscribe(uint16_t packetId) {\n Serial.println("Unsubscribe acknowledged.");\n Serial.print(" packetId: ");\n Serial.println(packetId);\n}*\/\n\nvoid onMqttPublish(uint16_t packetId) {\n Serial.print("Publish acknowledged.");\n Serial.print(" packetId: ");\n Serial.println(packetId);\n}\n\nvoid setup() {\n Serial.begin(115200);\n Serial.println();\n\n dht.begin();\n \n mqttReconnectTimer = xTimerCreate("mqttTimer", pdMS_TO_TICKS(2000), pdFALSE, (void*)0, reinterpret_cast<TimerCallbackFunction_t>(connectToMqtt));\n wifiReconnectTimer = xTimerCreate("wifiTimer", pdMS_TO_TICKS(2000), pdFALSE, (void*)0, reinterpret_cast<TimerCallbackFunction_t>(connectToWifi));\n\n WiFi.onEvent(WiFiEvent);\n\n mqttClient.onConnect(onMqttConnect);\n mqttClient.onDisconnect(onMqttDisconnect);\n \/\/mqttClient.onSubscribe(onMqttSubscribe);\n \/\/mqttClient.onUnsubscribe(onMqttUnsubscribe);\n mqttClient.onPublish(onMqttPublish);\n mqttClient.setServer(MQTT_HOST, MQTT_PORT);\n \/\/ If your broker requires authentication (username and password), set them below\n \/\/mqttClient.setCredentials("REPlACE_WITH_YOUR_USER", "REPLACE_WITH_YOUR_PASSWORD");\n connectToWifi();\n}\n\nvoid loop() {\n unsigned long currentMillis = millis();\n \/\/ Every X number of seconds (interval = 10 seconds) \n \/\/ it publishes a new MQTT message\n if (currentMillis - previousMillis >= interval) {\n \/\/ Save the last time a new reading was published\n previousMillis = currentMillis;\n \/\/ New DHT sensor readings\n hum = dht.readHumidity();\n \/\/ Read temperature as Celsius (the default)\n temp = dht.readTemperature();\n \/\/ Read temperature as Fahrenheit (isFahrenheit = true)\n \/\/temp = dht.readTemperature(true);\n\n \/\/ Check if any reads failed and exit early (to try again).\n if (isnan(temp) || isnan(hum)) {\n Serial.println(F("Failed to read from DHT sensor!"));\n return;\n }\n \n \/\/ Publish an MQTT message on topic esp32\/dht\/temperature\n uint16_t packetIdPub1 = mqttClient.publish(MQTT_PUB_TEMP, 1, true, String(temp).c_str()); \n Serial.printf("Publishing on topic %s at QoS 1, packetId: %i", MQTT_PUB_TEMP, packetIdPub1);\n Serial.printf("Message: %.2f \\n", temp);\n\n \/\/ Publish an MQTT message on topic esp32\/dht\/humidity\n uint16_t packetIdPub2 = mqttClient.publish(MQTT_PUB_HUM, 1, true, String(hum).c_str()); \n Serial.printf("Publishing on topic %s at QoS 1, packetId %i: ", MQTT_PUB_HUM, packetIdPub2);\n Serial.printf("Message: %.2f \\n", hum);\n }\n}\n<\/code><\/pre>\n\tHow the Code Works<\/h3>\n\n\n\n
#include \"DHT.h\"\n#include <WiFi.h>\nextern \"C\" {\n #include \"freertos\/FreeRTOS.h\"\n #include \"freertos\/timers.h\"\n}\n#include <AsyncMqttClient.h><\/code><\/pre>\n\n\n\n#define WIFI_SSID \"REPLACE_WITH_YOUR_SSID\"\n#define WIFI_PASSWORD \"REPLACE_WITH_YOUR_PASSWORD\"<\/code><\/pre>\n\n\n\n#define MQTT_HOST IPAddress(192, 168, 1, 106)<\/code><\/pre>\n\n\n\n#define MQTT_HOST \"example.com\"<\/code><\/pre>\n\n\n\n#define MQTT_PORT 1883<\/code><\/pre>\n\n\n\n#define MQTT_PUB_TEMP \"esp32\/dht\/temperature\"\n#define MQTT_PUB_HUM \"esp32\/dht\/humidity\"<\/code><\/pre>\n\n\n\n\/\/#define DHTTYPE DHT11 \/\/ DHT 11\n#define DHTTYPE DHT22 \/\/ DHT 22 (AM2302), AM2321\n\/\/#define DHTTYPE DHT21 \/\/ DHT 21 (AM2301)<\/code><\/pre>\n\n\n\nDHT dht(DHTPIN, DHTTYPE);<\/code><\/pre>\n\n\n\nfloat temp;\nfloat hum;<\/code><\/pre>\n\n\n\nAsyncMqttClient mqttClient;\nTimerHandle_t mqttReconnectTimer;\nTimerHandle_t wifiReconnectTimer;<\/code><\/pre>\n\n\n\nunsigned long previousMillis = 0; \/\/ Stores last time temperature was published\nconst long interval = 10000; \/\/ Interval at which to publish sensor readings<\/code><\/pre>\n\n\n\nMQTT functions: connect to Wi-Fi, connect to MQTT, and Wi-Fi events<\/h3>\n\n\n\n
void connectToWifi() {\n Serial.println(\"Connecting to Wi-Fi...\");\n WiFi.begin(WIFI_SSID, WIFI_PASSWORD);\n}<\/code><\/pre>\n\n\n\nvoid connectToMqtt() {\n Serial.println(\"Connecting to MQTT\u2026\");\n mqttClient.connect();\n }<\/code><\/pre>\n\n\n\nvoid WiFiEvent(WiFiEvent_t event) {\n Serial.printf(\"[WiFi-event] event: %d\\n\", event);\n switch(event) {\n case ARDUINO_EVENT_WIFI_STA_GOT_IP:\n Serial.println(\"WiFi connected\");\n Serial.println(\"IP address: \");\n Serial.println(WiFi.localIP());\n connectToMqtt();\n break;\n case ARDUINO_EVENT_WIFI_STA_DISCONNECTED:\n Serial.println(\"WiFi lost connection\");\n xTimerStop(mqttReconnectTimer, 0);\n xTimerStart(wifiReconnectTimer, 0);\n break;\n }\n}<\/code><\/pre>\n\n\n\nvoid onMqttConnect(bool sessionPresent) {\n Serial.println(\"Connected to MQTT.\");\n Serial.print(\"Session present: \");\n Serial.println(sessionPresent);\n}<\/code><\/pre>\n\n\n\nMQTT functions: disconnect and publish<\/h3>\n\n\n\n
void onMqttDisconnect(AsyncMqttClientDisconnectReason reason) {\n Serial.println(\"Disconnected from MQTT.\");\n if (WiFi.isConnected()) { \n xTimerStart(mqttReconnectTimer, 0);\n }\n}<\/code><\/pre>\n\n\n\nvoid onMqttPublish(uint16_t packetId) {\n Serial.println(\"Publish acknowledged.\");\n Serial.print(\" packetId: \");\n Serial.println(packetId);\n}<\/code><\/pre>\n\n\n\nsetup()<\/h3>\n\n\n\n
dht.begin();<\/code><\/pre>\n\n\n\nmqttReconnectTimer = xTimerCreate(\"mqttTimer\", pdMS_TO_TICKS(2000), pdFALSE, (void*)0, reinterpret_cast<TimerCallbackFunction_t>(connectToMqtt));\nwifiReconnectTimer = xTimerCreate(\"wifiTimer\", pdMS_TO_TICKS(2000), pdFALSE, (void*)0, reinterpret_cast<TimerCallbackFunction_t>(connectToWifi));<\/code><\/pre>\n\n\n\nWiFi.onEvent(WiFiEvent);<\/code><\/pre>\n\n\n\nmqttClient.onConnect(onMqttConnect);\nmqttClient.onDisconnect(onMqttDisconnect);\n\/\/mqttClient.onSubscribe(onMqttSubscribe);\n\/\/mqttClient.onUnsubscribe(onMqttUnsubscribe);\nmqttClient.onPublish(onMqttPublish);\nmqttClient.setServer(MQTT_HOST, MQTT_PORT);<\/code><\/pre>\n\n\n\nBroker Authentication<\/h4>\n\n\n\n
mqttClient.setCredentials(\"REPlACE_WITH_YOUR_USER\", \"REPLACE_WITH_YOUR_PASSWORD\");<\/code><\/pre>\n\n\n\nconnectToWifi();<\/code><\/pre>\n\n\n\nloop()<\/h2>\n\n\n\n
unsigned long currentMillis = millis();\n\/\/ Every X number of seconds (interval = 10 seconds) \n\/\/ it publishes a new MQTT message\nif (currentMillis - previousMillis >= interval) {\n \/\/ Save the last time a new reading was published\n previousMillis = currentMillis;\n \/\/ New DHT sensor readings\n hum = dht.readHumidity();\n \/\/ Read temperature as Celsius (the default)\n temp = dht.readTemperature();\n \/\/ Read temperature as Fahrenheit (isFahrenheit = true)\n \/\/temp = dht.readTemperature(true);<\/code><\/pre>\n\n\n\nPublishing to topics<\/h3>\n\n\n\n
uint16_t packetIdPub1 = mqttClient.publish(MQTT_PUB_TEMP, 1, true, String(temp).c_str());\nuint16_t packetIdPub2 = mqttClient.publish(MQTT_PUB_HUM, 1, true, String(hum).c_str());<\/code><\/pre>\n\n\n\n\n
\n
Uploading the code<\/h2>\n\n\n\n
![\"ESP32](\"https:\/\/i0.wp.com\/randomnerdtutorials.com\/wp-content\/uploads\/2020\/04\/ESP32-Publish-MQTT-DHT11-DHT22-Temperature-Serial-Monitor.png?resize=839%2C522&quality=100&strip=all&ssl=1\")
<\/figure><\/div>\n\n\nPreparing Node-RED Dashboard<\/h2>\n\n\n\n
\n
http://raspberry-pi-ip-address:1880<\/code><\/pre>\n\n\n\n![\"ESP32](\"https:\/\/i0.wp.com\/randomnerdtutorials.com\/wp-content\/uploads\/2020\/04\/0-ESP32-DHT11-DHT22-Arduino-IDE.png?resize=266%2C103&quality=100&strip=all&ssl=1\")
<\/figure><\/div>\n\n\n![\"MQTT](\"https:\/\/i0.wp.com\/randomnerdtutorials.com\/wp-content\/uploads\/2020\/04\/1-MQTT-In-Node-ESP32-Publish-Temperature-Humidity-Node-RED-Flow.png?resize=503%2C369&quality=100&strip=all&ssl=1\")
<\/figure><\/div>\n\n\n![\"ESP32](\"https:\/\/i0.wp.com\/randomnerdtutorials.com\/wp-content\/uploads\/2020\/04\/2-ESP32-Gauge-Temperature-Humidity-Node-RED-Flow.png?resize=497%2C603&quality=100&strip=all&ssl=1\")
<\/figure><\/div>\n\n\n![\"ESP32](\"https:\/\/i0.wp.com\/randomnerdtutorials.com\/wp-content\/uploads\/2020\/04\/3-ESP32-MQTT-Publish-Temperature-Humidity-Node-RED-Flow.png?resize=475%2C141&quality=100&strip=all&ssl=1\")
<\/figure><\/div>\n\n\n![\"Deploy](\"https:\/\/i0.wp.com\/randomnerdtutorials.com\/wp-content\/uploads\/2017\/06\/11_deploy_button.png?resize=138%2C40&quality=100&strip=all&ssl=1\")
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