ESP32-Temp_Sensor

by conrad.ict in Circuits > Microcontrollers

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ESP32-Temp_Sensor

This ESP32 project is compiled by cyberCon31 for Smart Home System.

Using ESP32, DHT11 sensor, LCD Display I2C.

This ESP32 project lets you monitor Temperature & Humidity via Web Browser thru local WLAN and via Blynk.cloud

Sensor readings for Temperature & Humidity can be viewed from the LCD Display I2C connected directly to ESP32 development board.

Created 03-April-2026 --- Code can be found here:

https://app.cirkitdesigner.com/project/7e7a299f-c679-481d-aae5-a2616033e5e7

My project was composed of combined codes from the following sources:

- LAFVIN -- Project_9_ESP32_DHT11_Web_Server

https://www.dropbox.com/sh/osi3jtv5ncuyby2/AADkuo03wGXK8JiwwbV3zPc6a?dl=0

- Tech Trends Shameer -- Temperature and Humidity Monitor Using ESP32 and Blynk IOT - Blynk 2.0 Projects

https://www.youtube.com/watch?v=gjYcLOoiH6c&t=82s$0

- shameermohamed -- Create temperature-humidity-monitor-using-esp32.ino

https://www.youtube.com/watch?v=gjYcLOoiH6c&t=23s

- ESP32 I/O --ESP32 - DHT11 - LCD

https://esp32io.com/tutorials/esp32-dht11-lcd$0

Thank you and 73!

de cyb3rc0n31

Supplies

List of components:

ESP32 Wifi IoT development board microcontroller
ESP32 expansion board
DHT11 sensor
LCD Display 16x2 with I2C

Upload Code Using Arduino IDE

This ESP32 code is compiled by cyberCon31 for Smart Home System.

Using ESP32, DHT11 sensor, LCD Display. This project can be locally viewed

from a web browser over Wifi, via Blynk.Cloud and via LCD display.

Created 03-April-2026

#define BLYNK_TEMPLATE_ID "Your Blynk Template ID"

#define BLYNK_TEMPLATE_NAME "Your Blynk template name"

#define BLYNK_AUTH_TOKEN "Your Bkynk Authentication Token"

#define BLYNK_PRINT Serial

// Import required libraries

#include "WiFi.h"

#include "ESPAsyncWebServer.h"

#include <Adafruit_Sensor.h>

#include <BlynkSimpleEsp32.h>

#include <Wire.h>

#include <LiquidCrystal_I2C.h>

#include <DHT.h>

// Replace with your network credentials

char auth[] = BLYNK_AUTH_TOKEN;

const char* ssid = "Your Wireless LAN or Wifi SSID";

const char* password = "Your Wifi SSID password";

#define DHTPIN 4 // Digital pin connected to the DHT11 sensor

// Uncomment the type of sensor in use:

#define DHTTYPE DHT11 // DHT 11

//#define DHTTYPE DHT22 // DHT 22 (AM2302)

//#define DHTTYPE DHT21 // DHT 21 (AM2301)

LiquidCrystal_I2C lcd(0x27, 16, 2); // I2C address 0x27 (from DIYables LCD), 16 column and 2 rows

DHT dht(DHTPIN, DHTTYPE);

// Create AsyncWebServer object on port 80

AsyncWebServer server(80);

String readDHTTemperature() {

// Sensor readings may also be up to 2 seconds 'old' (its a very slow sensor)

// Read temperature as Celsius (the default)

float t = dht.readTemperature();

// Read temperature as Fahrenheit (isFahrenheit = true)

//float t = dht.readTemperature(true);

// Check if any reads failed and exit early (to try again).

if (isnan(t)) {

Serial.println("Failed to read from DHT sensor!");

return "--";

}

else {

Serial.print("Temperature : ");

Serial.print(t);

return String(t);

}

String readDHTHumidity() {

// Sensor readings may also be up to 2 seconds 'old' (its a very slow sensor)

float h = dht.readHumidity();

if (isnan(h)) {

Serial.println("Failed to read from DHT sensor!");

return "--";

}

else {

Serial.print(" Humidity : ");

Serial.println(h);

return String(h);

}

BlynkTimer timer;

void sendSensor() {

float t = dht.readTemperature();

float h = dht.readHumidity();

Blynk.virtualWrite(V0, t);

Blynk.virtualWrite(V1, h);

}

const char index_html[] PROGMEM = R"rawliteral(

<!DOCTYPE HTML><html>

<head>

<style>

html {

font-family: Arial;

display: inline-block;

margin: 0px auto;

text-align: center;

}

h2 { font-size: 3.0rem; }

p { font-size: 3.0rem; }

.units { font-size: 1.2rem; }

.dht-labels{

font-size: 1.5rem;

vertical-align:middle;

padding-bottom: 15px;

}

</style>

</head>

<body>

<h2>ESP32 DHT Server</h2>

<h2>Smart-Home System by C.Cruz</h2>

<p>

<span class="dht-labels">Temperature</span>

<span id="temperature">%TEMPERATURE%</span>

</p>

<p>

<span class="dht-labels">Humidity</span>

<span id="humidity">%HUMIDITY%</span>

<sup class="units">&percnt;</sup>

</p>

</body>

setInterval(function ( ) {

var xhttp = new XMLHttpRequest();

xhttp.onreadystatechange = function() {

if (this.readyState == 4 && this.status == 200) {

document.getElementById("temperature").innerHTML = this.responseText;

}

};

xhttp.open("GET", "/temperature", true);

xhttp.send();

}, 10000 ) ;

setInterval(function ( ) {

var xhttp = new XMLHttpRequest();

xhttp.onreadystatechange = function() {

if (this.readyState == 4 && this.status == 200) {

document.getElementById("humidity").innerHTML = this.responseText;

}

};

xhttp.open("GET", "/humidity", true);

xhttp.send();

}, 10000 ) ;

</script>

</html>)rawliteral";

// Replaces placeholder with DHT values

String processor(const String& var){

//Serial.println(var);

if(var == "TEMPERATURE"){

return readDHTTemperature();

}

else if(var == "HUMIDITY"){

return readDHTHumidity();

}

return String();

}

void setup(){

// Serial port for debugging purposes

Serial.begin(115200);

dht.begin();

lcd.init(); // initialize the lcd

lcd.backlight(); // open the backlight

Blynk.begin(auth, ssid, password);

timer.setInterval(60000L, sendSensor); // set to send data every 1 minute.

//timer.setInterval(60000L, sendSensor); // 60,000ms = 1 minute

// Connect to Wi-Fi

WiFi.begin(ssid, password);

while (WiFi.status() != WL_CONNECTED) {

delay(1000);

Serial.println("Connecting to WiFi..");

}

// Print ESP32 Local IP Address

Serial.println(WiFi.localIP());

// Route for root / web page

server.on("/", HTTP_GET, [](AsyncWebServerRequest *request){

request->send_P(200, "text/html", index_html, processor);

});

server.on("/temperature", HTTP_GET, [](AsyncWebServerRequest *request){

request->send_P(200, "text/plain", readDHTTemperature().c_str());

});

server.on("/humidity", HTTP_GET, [](AsyncWebServerRequest *request){

request->send_P(200, "text/plain", readDHTHumidity().c_str());

});

// Start server

server.begin();

}

void loop(){

Blynk.run();

timer.run();

float h = dht.readHumidity(); // read humidity

float t = dht.readTemperature(); // read temperature

lcd.clear();

// check whether the reading is successful or not

if (isnan(t) || isnan(h)) {

lcd.setCursor(0, 0);

lcd.print("Sensor Failed...");

} else {

lcd.setCursor(0, 0);

lcd.print("Temp: ");

lcd.print(t);

lcd.write(223); // Degree symbol

lcd.print("C");

lcd.setCursor(0, 1); // display position

lcd.print("Humidity ");

lcd.print(h); // display the humidity

lcd.print(" %");

}

// wait a 2 seconds between readings

delay(5000);

}