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Arduino - Temperature via Web
In this tutorial, we will learn how to program Arduino to become a web server that provides you with the temperature via the web. You can access the web page provided by Arduino to check the temperature from a DS18B20 temperature sensor. The below is how it works:
- Arduino is programmed as a web server.
- You type the IP address of Arduino in a web browser on your smartphone or PC.
- Arduino responds to the request from the web browser with a web page that contains the temperature read from the DS18B20 sensor.
We will go through two example codes:
- Arduino code that provides a very simple web page that shows the temperature from the DS18B20 sensor. This makes it easy for you to understand how it works.
- Arduino code that provides a graphic web page that shows the temperature from the DS18B20 sensor.
Hardware Required
Or you can buy the following sensor kits:
| 1 | × | DIYables Sensor Kit (30 sensors/displays) | |
| 1 | × | DIYables Sensor Kit (18 sensors/displays) |
Please note: These are Amazon affiliate links. If you buy the components through these links, We will get a commission at no extra cost to you. We appreciate it.
Buy Note: Many DS18B20 sensors on the market are low-quality. We highly recommend buying the sensor from the DIYables brand using the link above. We tested it, and it worked well.
About Arduino Uno R4 and DS18B20 Temperature Sensor
If you do not know about Arduino Uno R4 and DS18B20 temperature sensor (pinout, how it works, how to program ...), learn about them in the following tutorials:
Wiring Diagram
This image is created using Fritzing. Click to enlarge image
Arduino Code - Simple Web Page
/*
* Created by ArduinoGetStarted.com
*
* This example code is in the public domain
*
* Tutorial page: https://arduinogetstarted.com/tutorials/arduino-temperature-via-web
*/
#include <WiFiS3.h>
#include <OneWire.h>
#include <DallasTemperature.h>
const char ssid[] = "YOUR_WIFI"; // change your network SSID (name)
const char pass[] = "YOUR_WIFI_PASSWORD"; // change your network password (use for WPA, or use as key for WEP)
const int SENSOR_PIN = 6; // Arduino pin connected to DS18B20 sensor's DQ pin
OneWire oneWire(SENSOR_PIN); // setup a oneWire instance
DallasTemperature tempSensor(&oneWire); // pass oneWire to DallasTemperature library
int status = WL_IDLE_STATUS;
WiFiServer server(80);
float getTemperature() {
tempSensor.requestTemperatures(); // send the command to get temperatures
float tempCelsius = tempSensor.getTempCByIndex(0); // read temperature in Celsius
return tempCelsius;
}
void setup() {
//Initialize serial and wait for port to open:
Serial.begin(9600);
tempSensor.begin(); // initialize the temperature sensor
String fv = WiFi.firmwareVersion();
if (fv < WIFI_FIRMWARE_LATEST_VERSION)
Serial.println("Please upgrade the firmware");
// attempt to connect to WiFi network:
while (status != WL_CONNECTED) {
Serial.print("Attempting to connect to SSID: ");
Serial.println(ssid);
// Connect to WPA/WPA2 network. Change this line if using open or WEP network:
status = WiFi.begin(ssid, pass);
// wait 10 seconds for connection:
delay(10000);
}
server.begin();
// you're connected now, so print out the status:
printWifiStatus();
}
void loop() {
// listen for incoming clients
WiFiClient client = server.available();
if (client) {
// read the HTTP request header line by line
while (client.connected()) {
if (client.available()) {
String HTTP_header = client.readStringUntil('\n'); // read the header line of HTTP request
if (HTTP_header.equals("\r")) // the end of HTTP request
break;
Serial.print("<< ");
Serial.println(HTTP_header); // print HTTP request to Serial Monitor
}
}
// send the HTTP response
// send the HTTP response header
client.println("HTTP/1.1 200 OK");
client.println("Content-Type: text/html");
client.println("Connection: close"); // the connection will be closed after completion of the response
client.println(); // the separator between HTTP header and body
// send the HTTP response body
client.println("<!DOCTYPE HTML>");
client.println("<html>");
client.println("<head>");
client.println("<link rel=\"icon\" href=\"data:,\">");
client.println("</head>");
client.println("<p>");
client.print("Temperature: <span style=\"color: red;\">");
float temperature = getTemperature();
client.print(temperature, 2);
client.println("°C</span>");
client.println("</p>");
client.println("</html>");
client.flush();
// give the web browser time to receive the data
delay(10);
// close the connection:
client.stop();
}
}
void printWifiStatus() {
// print your board's IP address:
Serial.print("IP Address: ");
Serial.println(WiFi.localIP());
// print the received signal strength:
Serial.print("signal strength (RSSI):");
Serial.print(WiFi.RSSI());
Serial.println(" dBm");
}
Quick Steps
- If this is the first time you use Arduino Uno R4, see how to setup environment for Arduino Uno R4 on Arduino IDE.
- Copy the above code and open with Arduino IDE
- Change the wifi information (SSID and password) in the code to yours
- Click Upload button on Arduino IDE to upload code to Arduino
- Open the Serial Monitor
- Check out the result on Serial Monitor.
COM6
Attempting to connect to SSID: YOUR_WIFI
IP Address: 192.168.0.2
signal strength (RSSI):-39 dBm
Autoscroll
Clear output
9600 baud
Newline
- You will find an IP address. Type this IP address into the address bar of a web browser on your smartphone or PC.
- You will see the following output on the Serial Monitor.
COM6
Attempting to connect to SSID: YOUR_WIFI
IP Address: 192.168.0.2
signal strength (RSSI):-41 dBm
New HTTP Request
<< GET / HTTP/1.1
<< Host: 192.168.0.2
<< Connection: keep-alive
<< Cache-Control: max-age=0
<< Upgrade-Insecure-Requests: 1
<< User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64)
<< Accept: text/html,application/xhtml+xml,application/xml
<< Accept-Encoding: gzip, deflate
<< Accept-Language: en-US,en;q=0.9
Autoscroll
Clear output
9600 baud
Newline
- You will see a very simple web page of Arduino board on the web browser as below:
Arduino Code - Graphic Web Page
As a graphic web page contains a large amount of HTML content, embedding it into the Arduino code as before becomes inconvenient. To address this, we need to separate the Arduino code and the HTML code into different files:
- The Arduino code will be placed in a .ino file.
- The HTML code (including HTML, CSS, and Javascript) will be placed in a .h file.
Quick Steps
- Open Arduino IDE and create new sketch, Give it a name, for example, ArduinoGetStarted.com.ino
- Copy the below code and open with Arduino IDE
/*
* Created by ArduinoGetStarted.com
*
* This example code is in the public domain
*
* Tutorial page: https://arduinogetstarted.com/tutorials/arduino-temperature-via-web
*/
#include <WiFiS3.h>
#include "index.h"
#include <OneWire.h>
#include <DallasTemperature.h>
const char ssid[] = "YOUR_WIFI"; // change your network SSID (name)
const char pass[] = "YOUR_WIFI_PASSWORD"; // change your network password (use for WPA, or use as key for WEP)
const int SENSOR_PIN = 6; // Arduino pin connected to DS18B20 sensor's DQ pin
OneWire oneWire(SENSOR_PIN); // setup a oneWire instance
DallasTemperature tempSensor(&oneWire); // pass oneWire to DallasTemperature library
int status = WL_IDLE_STATUS;
WiFiServer server(80);
float getTemperature() {
tempSensor.requestTemperatures(); // send the command to get temperatures
float tempCelsius = tempSensor.getTempCByIndex(0); // read temperature in Celsius
return tempCelsius;
}
void setup() {
//Initialize serial and wait for port to open:
Serial.begin(9600);
tempSensor.begin(); // initialize the temperature sensor
String fv = WiFi.firmwareVersion();
if (fv < WIFI_FIRMWARE_LATEST_VERSION)
Serial.println("Please upgrade the firmware");
// attempt to connect to WiFi network:
while (status != WL_CONNECTED) {
Serial.print("Attempting to connect to SSID: ");
Serial.println(ssid);
// Connect to WPA/WPA2 network. Change this line if using open or WEP network:
status = WiFi.begin(ssid, pass);
// wait 10 seconds for connection:
delay(10000);
}
server.begin();
// you're connected now, so print out the status:
printWifiStatus();
}
void loop() {
// listen for incoming clients
WiFiClient client = server.available();
if (client) {
// read the HTTP request header line by line
while (client.connected()) {
if (client.available()) {
String HTTP_header = client.readStringUntil('\n'); // read the header line of HTTP request
if (HTTP_header.equals("\r")) // the end of HTTP request
break;
Serial.print("<< ");
Serial.println(HTTP_header); // print HTTP request to Serial Monitor
}
}
// send the HTTP response
// send the HTTP response header
client.println("HTTP/1.1 200 OK");
client.println("Content-Type: text/html");
client.println("Connection: close"); // the connection will be closed after completion of the response
client.println(); // the separator between HTTP header and body
// send the HTTP response body
float temp = getTemperature();
String html = String(HTML_CONTENT);
html.replace("TEMPERATURE_MARKER", String(temp, 2)); // replace the marker by a real value
client.println(html);
client.flush();
// give the web browser time to receive the data
delay(10);
// close the connection:
client.stop();
}
}
void printWifiStatus() {
// print your board's IP address:
Serial.print("IP Address: ");
Serial.println(WiFi.localIP());
// print the received signal strength:
Serial.print("signal strength (RSSI):");
Serial.print(WiFi.RSSI());
Serial.println(" dBm");
}
- Change the WiFi information (SSID and password) in the code to yours
- Create the index.h file On Arduino IDE by:
- Either click on the button just below the serial monitor icon and choose New Tab, or use Ctrl+Shift+N keys.
- Give the file's name index.h and click OK button
- Copy the below code and paste it to the index.h.
- Now you have the code in two files: ArduinoGetStarted.com.ino and index.h
- Click Upload button on Arduino IDE to upload code to Arduino
- Access the web page of Arduino board via web browser as before. You will see it as below:
- If you make changes to the HTML content within the index.h file but don't modify anything in the ArduinoGetStarted.com.ino file, the Arduino IDE won't refresh or update the HTML content when you compile and upload the code to the ESP32.
- To force the Arduino IDE to update the HTML content in this situation, you need to make a modification in the ArduinoGetStarted.com.ino file. For example, you can add an empty line or insert a comment. This action triggers the IDE to recognize that there have been changes in the project, ensuring that your updated HTML content gets included in the upload.
/*
* Created by ArduinoGetStarted.com
*
* This example code is in the public domain
*
* Tutorial page: https://arduinogetstarted.com/tutorials/arduino-temperature-via-web
*/
const char *HTML_CONTENT = R""""(
<!DOCTYPE html>
<html>
<head>
<title>Arduino - Web Temperature</title>
<meta name="viewport" content="width=device-width, initial-scale=0.7, maximum-scale=0.7">
<meta charset="utf-8">
<link rel="icon" href="https://diyables.io/images/page/diyables.svg">
<style>
body { font-family: "Georgia"; text-align: center; font-size: width/2pt;}
h1 { font-weight: bold; font-size: width/2pt;}
h2 { font-weight: bold; font-size: width/2pt;}
button { font-weight: bold; font-size: width/2pt;}
</style>
<script>
var cvs_width = 200, cvs_height = 450;
function init() {
var canvas = document.getElementById("cvs");
canvas.width = cvs_width;
canvas.height = cvs_height + 50;
var ctx = canvas.getContext("2d");
ctx.translate(cvs_width/2, cvs_height - 80);
update_view(TEMPERATURE_MARKER);
}
function update_view(temp) {
var canvas = document.getElementById("cvs");
var ctx = canvas.getContext("2d");
var radius = 70;
var offset = 5;
var width = 45;
var height = 330;
ctx.clearRect(-cvs_width/2, -350, cvs_width, cvs_height);
ctx.strokeStyle="blue";
ctx.fillStyle="blue";
//5-step Degree
var x = -width/2;
ctx.lineWidth=2;
for (var i = 0; i <= 100; i+=5) {
var y = -(height - radius)*i/100 - radius - 5;
ctx.beginPath();
ctx.lineTo(x, y);
ctx.lineTo(x - 20, y);
ctx.stroke();
}
//20-step Degree
ctx.lineWidth=5;
for (var i = 0; i <= 100; i+=20) {
var y = -(height - radius)*i/100 - radius - 5;
ctx.beginPath();
ctx.lineTo(x, y);
ctx.lineTo(x - 25, y);
ctx.stroke();
ctx.font="20px Georgia";
ctx.textBaseline="middle";
ctx.textAlign="right";
ctx.fillText(i.toString(), x - 35, y);
}
// shape
ctx.lineWidth=16;
ctx.beginPath();
ctx.arc(0, 0, radius, 0, 2 * Math.PI);
ctx.stroke();
ctx.beginPath();
ctx.rect(-width/2, -height, width, height);
ctx.stroke();
ctx.beginPath();
ctx.arc(0, -height, width/2, 0, 2 * Math.PI);
ctx.stroke();
ctx.fillStyle="#e6e6ff";
ctx.beginPath();
ctx.arc(0, 0, radius, 0, 2 * Math.PI);
ctx.fill();
ctx.beginPath();
ctx.rect(-width/2, -height, width, height);
ctx.fill();
ctx.beginPath();
ctx.arc(0, -height, width/2, 0, 2 * Math.PI);
ctx.fill();
ctx.fillStyle="#ff1a1a";
ctx.beginPath();
ctx.arc(0, 0, radius - offset, 0, 2 * Math.PI);
ctx.fill();
temp = Math.round(temp * 100) / 100;
var y = (height - radius)*temp/100.0 + radius + 5;
ctx.beginPath();
ctx.rect(-width/2 + offset, -y, width - 2*offset, y);
ctx.fill();
ctx.fillStyle="red";
ctx.font="bold 34px Georgia";
ctx.textBaseline="middle";
ctx.textAlign="center";
ctx.fillText(temp.toString() + "°C", 0, 100);
}
window.onload = init;
</script>
</head>
<body>
<h1>Arduino - Web Temperature</h1>
<canvas id="cvs"></canvas>
</body>
</html>
)"""";
※ NOTE THAT:
