Sending sensor data to a web server

Build your own IOT service! Collect sensor data and send it to a web/database server.

Today’s project uses an Arduino equipped with a Ethernet shield, and a DHT-11 temperature / humidity sensor.

Arduino UNO
Arduino Ethernet Shield
DHT-11 Module

(ESP8266 / BME280 Version)
(UNO / WiFi BME280 Version)

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The Arduino reads the DHT-11, and submits the data to a php script on a hosted web server. That php page inserts the data into a mySQL database, and another php page creates a web page displaying the data as you can see below.

Every 5 minutes the Arduino submits a new data packet.

For the server side code.

For Heat Index, Dew Point, and Wind Chill calculations.

The Arduino sketch is below:

#include <DHT.h>
#include <Ethernet.h>
#include <SPI.h>

byte mac[] = { 0x00, 0xAA, 0xBB, 0xCC, 0xDE, 0x01 }; // RESERVED MAC ADDRESS
EthernetClient client;

#define DHTPIN 6 // SENSOR PIN
#define DHTTYPE DHT11 // SENSOR TYPE – THE ADAFRUIT LIBRARY OFFERS SUPPORT FOR MORE MODELS
DHT dht(DHTPIN, DHTTYPE);

long previousMillis = 0;
unsigned long currentMillis = 0;
long interval = 250000; // READING INTERVAL

int t = 0; // TEMPERATURE VAR
int h = 0; // HUMIDITY VAR
String data;

void setup() {
Serial.begin(115200);

pinMode(7, OUTPUT);      // sets the digital pin as output
pinMode(5, OUTPUT);      // sets the digital pin as output
digitalWrite(7, HIGH);
digitalWrite(5, LOW);

if (Ethernet.begin(mac) == 0) {
Serial.println(“Failed to configure Ethernet using DHCP”);
}

dht.begin();
delay(10000); // GIVE THE SENSOR SOME TIME TO START

h = (int) dht.readHumidity();
t = (int) dht.readTemperature();

data = “”;
}

void loop(){

currentMillis = millis();
if(currentMillis – previousMillis > interval) { // READ ONLY ONCE PER INTERVAL
previousMillis = currentMillis;
h = (int) dht.readHumidity();
t = (int) dht.readTemperature();
}

data = “temp1=”;

data.concat(t);

data.concat(“&hum1=”);

data.concat(h);

if (client.connect(“www.xxxxxx.com”,80)) { // REPLACE WITH YOUR SERVER ADDRESS
client.println(“POST /add.php HTTP/1.1”);
client.println(“Host: xxxxxx.com”); // SERVER ADDRESS HERE TOO
client.println(“Content-Type: application/x-www-form-urlencoded”);
client.print(“Content-Length: “);
client.println(data.length());
client.println();
client.print(data);
}

if (client.connected()) {
client.stop(); // DISCONNECT FROM THE SERVER
}

delay(300000); // WAIT FIVE MINUTES BEFORE SENDING AGAIN
}

If you are interested in recreating this project, the zip file with the Arduino code, libraries, php pages, and sql for the mySQL database is available at files

Customized projects available as well as hosting and support.

This project inspired by https://github.com/alexpais/iot-arduino-weather-station

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