Dht11 Esp8266 Arduino Uno | Esp8266 Dht Server

ESP8266 DHT Server

Temperature


%TEMPERATURE%


^°C

Humidity


%HUMIDITY%

)rawliteral”; // Replaces placeholder with DHT values String processor(const String& var){ //Serial.println(var); if(var == “TEMPERATURE”){ return String(t); } else if(var == “HUMIDITY”){ return String(h); } return String(); } void setup(){ // Serial port for debugging purposes Serial.begin(115200); dht.begin(); // Connect to Wi-Fi WiFi.begin(ssid, password); Serial.println(“Connecting to WiFi”); while (WiFi.status() != WL_CONNECTED) { delay(1000); Serial.println(“.”); } // Print ESP8266 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”, String(t).c_str()); }); server.on(“/humidity”, HTTP_GET, [](AsyncWebServerRequest *request){ request->send_P(200, “text/plain”, String(h).c_str()); }); // Start server server.begin(); } void loop(){ unsigned long currentMillis = millis(); if (currentMillis – previousMillis >= interval) { // save the last time you updated the DHT values previousMillis = currentMillis; // Read temperature as Celsius (the default) float newT = dht.readTemperature(); // Read temperature as Fahrenheit (isFahrenheit = true) //float newT = dht.readTemperature(true); // if temperature read failed, don’t change t value if (isnan(newT)) { Serial.println(“Failed to read from DHT sensor!”); } else { t = newT; Serial.println(t); } // Read Humidity float newH = dht.readHumidity(); // if humidity read failed, don’t change h value if (isnan(newH)) { Serial.println(“Failed to read from DHT sensor!”); } else { h = newH; Serial.println(h); } } }

Insert your network credentials in the following variables and the code will work straight away.


const char* ssid = "REPLACE_WITH_YOUR_SSID"; const char* password = "REPLACE_WITH_YOUR_PASSWORD";


How the Code Works

In the following paragraphs we’ll explain how the code works. Keep reading if you want to learn more or jump to the Demonstration section to see the final result.

Importing libraries

First, import the required libraries.


#include

#include

#include

#include

#include

#include

#include








Setting your network credentials

Insert your network credentials in the following variables, so that the ESP8266 can connect to your local network.


const char* ssid = "REPLACE_WITH_YOUR_SSID"; const char* password = "REPLACE_WITH_YOUR_PASSWORD";


Variables definition

Define the GPIO that the DHT data pin is connected to. In this case, it’s connected to GPIO5 (D1).


#define DHTPIN 5 // Digital pin connected to the DHT sensor


Then, select the DHT sensor type you’re using. In our example, we’re using the DHT22. If you’re using another type, you just need to uncomment your sensor and comment all the others.


#define DHTTYPE DHT22 // DHT 22 (AM2302)


Instantiate a DHTobject with the type and pin defined earlier.


DHT dht(DHTPIN, DHTTYPE);


Create an AsyncWebServerobject on port 80.


AsyncWebServer server(80);


Create float variables to hold the current temperature and humidity values. The temperature and humidity are updated in the loop().


float t = 0.0; float h = 0.0;


Create timer variables needed to update the temperature readings every 10 seconds.


unsigned long previousMillis = 0; // will store last time DHT was updated // Updates DHT readings every 10 seconds const long interval = 10000;


Building the Web Page

Proceeding to the web server page.

As you can see in the above figure, the web page shows one heading and two paragraphs. There is a paragraph to display the temperature and another to display the humidity. There are also two icons to style the page.

Let’s see how this web page is created.

All the HTML text with styles included is stored in the index_html variable. Now we’ll go through the HTML text and see what each part does.

The following tag makes your web page responsive in any browser.

The tag is needed to load the icons from the fontawesome website.

Styles

Between the tags, we add some CSS to style the web page.

Basically, we’re setting the HTML page to display the text with Arial font in block without margin, and aligned at the center.


html { font-family: Arial; display: inline-block; margin: 0px auto; text-align: center; }


We set the font size for the heading (h2), paragraph (p) and the units(.units) of the readings.


h2 { font-size: 3.0rem; } p { font-size: 3.0rem; } .units { font-size: 1.2rem; }


The labels for the readings are styled as shown below:


dht-labels{ font-size: 1.5rem; vertical-align:middle; padding-bottom: 15px; }


All of the previous tags should go between the

and

tags. These tags are used to include content that is not directly visible to the user, like the , the tags, and the styles.

HTML Body

Inside the tags is where we add the web page content.

The tags add a heading to the web page. In this case, the “ESP8266 DHT server” text, but you can add any other text.

ESP8266 DHT Server

Then, there are two paragraphs. One to display the temperature and the other to display the humidity. The paragraphs are delimited by the

and

tags. The paragraph for the temperature is the following:

Temperature


%TEMPERATURE%


^°C

And the paragraph for the humidity is on the following snipet:

Humidity


%HUMIDITY%

The

tags display the fontawesome icons.

How to display icons

To chose the icons, go to the Font Awesome Icons website.

Search the icon you’re looking for. For example, “thermometer”.

Click the desired icon. Then, you just need to copy the HTML text provided.

To chose the color, you just need to pass the style parameter with the color in hexadecimal, as follows:

Proceeding with the HTML text…

The next line writes the word “Temperature” into the web page.



Temperature



The TEMPERATURE text between % signs is a placeholder for the temperature value.



%TEMPERATURE%



This means that this %TEMPERATURE% text is like a variable that will be replaced by the actual temperature value from the DHT sensor. The placeholders on the HTML text should go between % signs.

Finally, we add the degree symbol.



°C



The tags make the text superscript.

We use the same approach for the humidity paragraph, but it uses a different icon and the %HUMIDITY% placeholder.

Humidity


%HUMIDITY%

Automatic Updates

Finally, there’s some JavaScript code in our web page that updates the temperature and humidity automatically, every 10 seconds.

Scripts in HTML text should go between the tags.

To update the temperature on the background, we have a setInterval() function that runs every 10 seconds.

Basically, it makes a request in the /temperature URL to get the latest temperature reading.


xhttp.open("GET", "/temperature", true); xhttp.send(); }, 10000 ) ;


When it receives that value, it updates the HTML element whose id is temperature.


if (this.readyState == 4 && this.status == 200) { document.getElementById("temperature").innerHTML = this.responseText; }


In summary, this previous section is responsible for updating the temperature asynchronously. The same process is repeated for the humidity readings.

Important: since the DHT sensor is quite slow getting the readings, if you plan to have multiple clients connected to an ESP8266 at the same time, we recommend increasing the request interval or remove the automatic updates.

Processor

Now, we need to create the processor() function, that will replace the placeholders in our HTML text with the actual temperature and humidity values.


String processor(const String& var){ //Serial.println(var); if(var == "TEMPERATURE"){ return String(t); } else if(var == "HUMIDITY"){ return String(h); } return String(); }


When the web page is requested, we check if the HTML has any placeholders. If it finds the %TEMPERATURE% placeholder, we return the temperature that is stored on the t variable.


if(var == "TEMPERATURE"){ return String(t); }


If the placeholder is %HUMIDITY%, we return the humidity value.


else if(var == "HUMIDITY"){ return String(h); }


setup()

In the setup(), initialize the Serial Monitor for debugging purposes.


Serial.begin(115200);


Initialize the DHT sensor.


dht.begin();


Connect to your local network and print the ESP8266 IP address.


WiFi.begin(ssid, password); while (WiFi.status() != WL_CONNECTED) { delay(1000); Serial.println("Connecting to WiFi.."); }


Finally, add the next lines of code to handle the web server.


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", String(t).c_str()); }); server.on("/humidity", HTTP_GET, [](AsyncWebServerRequest *request){ request->send_P(200, "text/plain", String(h).c_str()); });


When we make a request on the root URL, we send the HTML text that is stored on the index_html variable. We also need to pass the processorfunction, that will replace all the placeholders with the right values.


server.on("/", HTTP_GET, [](AsyncWebServerRequest *request){ request->send_P(200, "text/html", index_html, processor); });


We need to add two additional handlers to update the temperature and humidity readings. When we receive a request on the /temperature URL, we simply need to send the updated temperature value. It is plain text, and it should be sent as a char, so, we use the c_str() method.


server.on("/temperature", HTTP_GET, [](AsyncWebServerRequest *request){ request->send_P(200, "text/plain", String(t).c_str()); });


The same process is repeated for the humidity.


server.on("/humidity", HTTP_GET, [](AsyncWebServerRequest *request){ request->send_P(200, "text/plain", String(h).c_str()); });


Lastly, we can start the server.


server.begin();


In the loop() is where we get new temperature readings from the sensor every 10 seconds.

Basically, we check if it is time to get new sensor readings:


if (currentMillis - previousMillis >= interval) {


If it is, we store a new temperature reading on the newT variable


float newT = dht.readTemperature();


If the newT variable is a valid temperature readings, we update the t variable.


else { t = newT; Serial.println(t); }


The same process is repeated for the humidity.


// Read Humidity float newH = dht.readHumidity(); // if humidity read failed, don't change h value if (isnan(newH)) { Serial.println("Failed to read from DHT sensor!"); } else { h = newH; Serial.println(h); }


That’s pretty much how the code works.

Uploading the code

After modifying the sketch with the necessary changes, if needed, upload the code to your ESP8266 (if you can’t upload code to your ESP8266, read this troubleshooting guide).

Make sure you have the right board and COM port select. Go to Tools> Board and select the ESP8266 model you’re using. In our case, we’re using the ESP8266 12-E NodeMCU Kit.

Go to Tools > Port and select the COM port the ESP8266 is connected to.

Press the Arduino IDE upload button.

Note: if you’re using an ESP-01, you need a serial adapter or an FTDI programmer to upload code.

ESP8266 IP Address

After uploading the code, open the Serial Monitor at a baud rate of 115200. Press the ESP8266 reset button. The ESP8266 IP address will be printed in the serial monitor as shown in the following figure.

Demonstration

In your local network, go to a browser and type the ESP8266 IP address. It should display the following web page with the latest sensor readings.

The temperature and humidity readings update automatically every 10 seconds without the need to refresh the web page.

Cảm biến nhiệt độ, độ ẩm DHT11

Cảm biến độ ẩm và nhiệt độ DHT11 là cảm biến rất thông dụng hiện nay vì chi phí rẻ và rất dễ lấy dữ liệu thông qua chuẩn giao tiếp 1 wire.

Chuẩn giao tiếp 1 wire là dùng 1 chân Digital để truyền dữ liệu.

Bộ tiền xử lý tín hiệu được tích hợp trong cảm biến giúp bạn có thể đọc dữ liệu chính xác mà không phải qua bất kỳ tính toán nào.

Thông số kỹ thuật của cảm biến:

• Điện áp hoạt động: 3V – 5V (DC)
• Dãi độ ẩm hoạt động: 20% – 90% RH, sai số ±5%RH
• Dãi nhiệt độ hoạt động: 0°C ~ 50°C, sai số ±2°C
• Khoảng cách truyển tối đa: 20m

Các bạn download và cài đặt thư viện hỗ trợ sử dụng DHT11: Tại đây

Code

#include “DHT.h”
#define DHTTYPE DHT11 // DHT 11
const int DHTPin = 4;
DHT dht(DHTPin, DHTTYPE); // Initialize DHT sensor.
static char celsiusTemp[7];
static char fahrenheitTemp[7];
static char humidityTemp[7];
void setup() {
Serial.begin(9600);
delay(10);
dht.begin();
}
void loop() {
// Sensor readings may also be up to 2 seconds ‘old’ (its a very slow sensor)
float h = dht.readHumidity();
// Read temperature as Celsius (the default)
float t = dht.readTemperature();
// Read temperature as Fahrenheit (isFahrenheit = true)
float f = dht.readTemperature(true);
// Check if any reads failed and exit early (to try again).
if (isnan(h) || isnan(t) || isnan(f)) {
Serial.println(“Failed to read from DHT sensor!”);
}
else {
delay(2000);
Serial.print(“Humidity: “);
Serial.print(h);
Serial.print(” %\t Temperature: “);
Serial.print(t);
Serial.print(” *C “);
Serial.print(f);
Serial.print(” *F\t Heat index: “);
Serial.print(hic);
Serial.print(” *C “);
Serial.println(hif);
}
}

Demonstration

After making any necessary changes, upload the code to the ESP8266 as described in an earlier section.

Open the Arduino IDE serial monitor at a baud rate of 115200. After a few seconds your IP address should show up. In our case it’s 192.168.1.95.

Open any browser from a device that is connected to the same router that your ESP is. Then type the IP address and click Enter!

Now you should see the latest temperature and humidity readings. To update the readings, you just need to refresh the web page.

Wrapping Up

In this project we’ve shown you how to display sensor readings from a DHT sensor on a web page. We’ve provided two examples: a simple web server and an asynchronous web server with auto-updates.

Now, you can easily modify the examples provided to display readings from other sensors. If you like the ESP8266 and IoT projects take a look at some of our resources:

• Home Automation with ESP8266 (Course)
• Learn ESP32 with Arduino IDE (Course)
• MicroPython Programming with ESP32 and ESP8266 (ebook)

You may also like some of our most popular projects with the ESP8266:

• Hack a PIR Motion Sensor with an ESP8266
• Build a Multisensor Shield for ESP8266
• ESP8266 Wi-Fi Button – DIY Amazon Dash Button Clone
• 30+ ESP8266 Projects

Do you have any questions? Leave a comment below!

Thanks for reading.

Module cảm biến nhiệt độ và độ ẩm DHT11 esp8266-01s là mdodule cảm biến được sử dụng phổ biến trong việc đo nhiệt độ và độ ẩm bởi độ chính xác cao, giá thành rẻ, dễ sử dụng.

Module cảm biến nhiệt độ và độ ẩm

Module cảm biến nhiệt độ và độ ẩm DHT11

Module cảm biến DHT11 esp8266-01s

Mặt sau của Module cảm biến DHT11 esp8266-01s

Kích thước Module cảm biến DHT11 esp8266-01s

Bảng Thông Số Module Cảm Biến DHT11

Chân Kết Nối Module Cảm Biến DHT11

Module Cảm Biến DHT11

Module Cảm Biến DHT11

Module Cảm Biến DHT11

Chế độ bảo hành

Chế độ bảo hành sản phẩm của Linh Kiện Điện Tử 3M

Bảo đảm chất lượng

Sản phẩm được Test, dán Tem trước khi được đóng gói Kĩ Càng gửi cho Quý Khách

Cước vận chuyển

Cước vận chuyển được tự động đồng bộ đơn vị vận chuyển, Sản phẩm phát ngay trong ngày. Hỗ trợ đơn hàng: 02420214848

Hỗ trợ kỹ thuật

Tư vấn kĩ thuật: 0969.477.417 Khi khách hàng gặp khó khăn trong quá trình sử dụng

Thành tiền:

Module WiFi Nhiệt Độ Độ Ẩm DHT11 sử dụng ESP8266-01/ESP-01S làm bộ điều khiển chính và DHT11 làm cảm biến nhiệt độ và độ ẩm. ESP8266 thu thập nhiệt độ và độ ẩm trong môi trường và tải nó lên máy chủ. Hỗ trợ nguồn DC 3.7v-12V (pin lithium 3.7V). Nó có thể được sử dụng như một nút thu thập nhiệt độ và độ ẩm cho các dự án nhà thông minh hoặc IOT.

THông số kỹ thuật Module WiFi Nhiệt Độ Độ Ẩm DHT11*Điều khiển chính: ESP-01/ESP-01S (mô-đun này chưa bao gồm ESP-01/ESP-01S)* Cảm biến nhiệt độ và độ ẩm: DHT11* Điện áp làm việc: DC 3.7V-12V (hỗ trợ nguồn pin lithium 3.7v)* Dải đo: 20-90%RH 0-50℃*Độ chính xác của phép đo: Nhiệt độ: ±2°C Độ ẩm ±5%RH

Ví dụ ứng dụng Module WiFi ESP8266 DHT11:1. Nguồn điện: Nguồn điện một chiều 3.7V-12V được kết nối với VCC GND (đầu cắm chân cắm 2.54mm)2. Tải chương trình xuống ESP-01S (kết nối này không bao gồm mô-đun không dây này)3. Chèn ESP-01/ESP-01S (kết nối này không bao gồm mô-đun không dây này) vào đầu cái 2*4 Pin (theo hướng mũi tên)

#esp8266 #dht11 #wifi

I am trying to get a DHT11 temperature/humidity sensor working with an ESP8266. The sensor I have is of the 3 pin variety with built-in resistor. I started with a simple example and got it working on a Uno to show the temperature and humidity on the display with no difficulty. However, I cannot get it to work on the ESP8266.

For the Uno, I downloaded the library referenced here:

https://playground.arduino.cc/Main/DHT11Lib/

The dht11.cpp and dht11.h files were added to my project directory and included in the sketch and this works well on the Uno giving me both temperature and humidity readings. However on the ESP8266 there are no readings at all, just zero values returned for both temperature and humidity. I thought that I maybe needed to use a library specific to the platform so I also tried DHTesp from here:

This was downloaded using the Library Manager and I found that it also does not return any data although instead of showing zero, the display now shows ‘nan’ for both parameters. I have also tried different GPIO pins. The datasheet shows these operating from 3.5V to 5V, but I found at least a couple of tutorials using this on the 3.3V. Nevertheless, I also tried powering the sensor from 5v, but still get the same result. Connecting the sensor back up to the Uno shows that it works perfectly. Here is my code:


#include #ifdef __AVR__ #include "dht11.h" #define DHT11PIN 13 dht11 dhtSensor; LiquidCrystal lcd(8, 9, 4, 5, 6, 7); #endif #if defined(ESP32) || defined(ESP8266) #include "DHTesp.h" #define DHT11PIN 2 // #define FAN 2 DHTesp dhtSensor; LiquidCrystal lcd(5, 4, 14, 12, 13, 15); #endif //uint8_t pos = 0; void setup() { Serial.begin(115200); #ifdef ESP8266 dhtSensor.setup(DHT11PIN, DHTesp::DHT22); #endif lcd.begin(16, 2); } void loop() { Serial.println(); #ifdef __AVR__ int chk = dhtSensor.read(DHT11PIN); float temperature = (float)dhtSensor.temperature; float humidity = (float)dhtSensor.humidity; #endif #if defined(ESP32) || defined(ESP8266) float temperature = dhtSensor.getTemperature(); float humidity = dhtSensor.getHumidity(); #endif // int chk = DHT11.read(DHT11PIN); outputSerial(temperature, humidity); /* lcd.setCursor(0,0); lcd.print("Hello, world!"); if (pos>0) lcd.setCursor(pos-1,1); lcd.print(" "); lcd.setCursor(pos,1); lcd.print(">"); if (pos==0) lcd.setCursor(15,1); lcd.print(" "); pos<15 ? pos += 1 : pos = 0; */ updateDisplay(temperature, humidity); delay(2000); } void outputSerial(float temp, float humid){ Serial.print("Temp (°C): "); Serial.print(temp, 2); Serial.print("\t"); Serial.print("Humidity (%): "); Serial.print(humid, 2); Serial.println(); } void updateDisplay(float temp, float humid){ // Header lcd.setCursor(0,0); lcd.print("Tmp | Hum | Fan"); //Temperature lcd.setCursor(0,1); lcd.print(temp,0); lcd.print((char)223); lcd.setCursor(4,1); lcd.print("|"); // Humidity lcd.setCursor(6,1); lcd.print(humid,0); lcd.print("%"); lcd.setCursor(10,1); lcd.print("|"); // Fan status lcd.setCursor(12,1); fanOn(humid) ? lcd.print("ON ") : lcd.print("OFF"); } bool fanOn(float humid){ if (humid>50) return true; return false; }

I understand that the DHT22 is more accurate and the better sensor, but for now the DHT11 is what I have to work and would at least like to get it up and running on the ESP8266 in principle. Can anyone suggest what might be preventing it from working? Do I need the 4 wire version for example?