Introduction: The Super Simple Arduino Weather Web Server
From the minds at http://arduinotronics.blogspot.com/
Updates:
Added Heat Index & Dew Point calculations
Added Barometric Pressure Sensor
See the new BME280 combination Temperature, Humidity, AND Barometric Pressure Sensor all in one!
6/2/2015 See the new WiFi Version! - http://arduinotronics.blogspot.com/2015/06/wifi-we...
I wanted to set up a home web server that could monitor indoor and outdoor temperature, humidity levels, and even monitor for indoor freezing or flooding conditions (and other security, appliance or environmental alerts). The approach I took consists of a Arduino and a Ethernet shield, running a tiny web server sketch, and for this example, I'm using the popular DHT-11 Temperature / Humidity module. You can interface this to smoke / heat sensors, CO and other gas sensors, and a whole lot more.
For this example you will need:
Arduino
Ethernet Shield (this could be done with wifi as well with some code changes)
DHT-11 Temp/Humidity Module
10k Ohm Resistor
Optional: BMP-085 Barometric Pressure Sensor
A internet router and home internet access
Step 1: The DHT-11 Temperature / Humidity Sensor
This little 4 pin sensor (only 3 are used) is an inexpensive and common sensor. It's easy to use and connect. Pin 1 connects to +5v, Pin 2 to an Arduino Input (we are using D2 on the Arduino), and pin 4 to Arduino Gnd. Since the Ethernet shield will stack on top of the Arduino, plug the DHT-11 into the same pins on the Ethernet shield.
The ethernet shield uses pins A0, A1, D4, and D10-D13
The DHT-11 is using D2, but can be changed.
The BMP180 uses A4 & A5.
Step 2: The Ethernet Shield
This shield from Arduino (the company) gives your Arduino (the board) the ability to communicate over the network, and internet. Write down the MAC address on the back, then plug the shield in, on top of your arduino, and connect a Ethernet cable to your router.
Step 3: The Code
I've adapted the sample Web Server app included with the Arduino, by merging the DHTxx code and library from Lady Ada. This basically changes Serial.print statements to client.print, and I've massaged the html a bit to make it display nicer. You can download the code at
http://arduinotronics.blogspot.com/2013/09/arduino-temp-humidity-web-server.html
#include <DHT.h>
#define DHTPIN 2 // what pin we're connected to
// Uncomment whatever type you're using!
#define DHTTYPE DHT11 // DHT 11
//#define DHTTYPE DHT22 // DHT 22 (AM2302)
//#define DHTTYPE DHT21 // DHT 21 (AM2301)
// Connect pin 1 (on the left) of the sensor to +5V
// Connect pin 2 of the sensor to whatever your DHTPIN is
// Connect pin 4 (on the right) of the sensor to GROUND
// Connect a 10K resistor from pin 2 (data) to pin 1 (power) of the sensor
DHT dht(DHTPIN, DHTTYPE);
#include <SPI.h>
#include <Ethernet.h>
// Enter a MAC address and IP address for your controller below.
// The IP address will be dependent on your local network:
byte mac[] = {
0x90, 0xA2, 0xDA, 0x00, 0x23, 0x36 }; //MAC address found on the back of your ethernet shield.
IPAddress ip(192,168,254,177); // IP address dependent upon your network addresses.
// Initialize the Ethernet server library
// with the IP address and port you want to use
// (port 80 is default for HTTP):
EthernetServer server(80);
void setup() {
// Open serial communications and wait for port to open:
Serial.begin(9600);
while (!Serial) {
; // wait for serial port to connect. Needed for Leonardo only
}
dht.begin();
// start the Ethernet connection and the server:
Ethernet.begin(mac, ip);
server.begin();
Serial.print("server is at ");
Serial.println(Ethernet.localIP());
}
void loop() {
// Reading temperature or humidity takes about 250 milliseconds!
// Sensor readings may also be up to 2 seconds 'old' (its a very slow sensor)
float h = dht.readHumidity();
float t = dht.readTemperature();
// check if returns are valid, if they are NaN (not a number) then something went wrong!
if (isnan(t) || isnan(h)) {
Serial.println("Failed to read from DHT");
} else {
Serial.print("Humidity: ");
Serial.print(h);
Serial.print(" %\t");
Serial.print("Temperature: ");
Serial.print(t);
Serial.println(" *C");
}
// listen for incoming clients
EthernetClient client = server.available();
if (client) {
Serial.println("new client");
// an http request ends with a blank line
boolean currentLineIsBlank = true;
while (client.connected()) {
if (client.available()) {
char c = client.read();
Serial.write(c);
// if you've gotten to the end of the line (received a newline
// character) and the line is blank, the http request has ended,
// so you can send a reply
if (c == '\n' && currentLineIsBlank) {
// send a standard 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("Refresh: 5"); // refresh the page automatically every 5 sec
client.println();
client.println("<!DOCTYPE HTML>");
client.println("<html>");
// output the value of the DHT-11
client.println("<H2>");
client.print("Humidity: ");
client.println("</H2>");
client.println("<p />");
client.println("<H1>");
client.print(h);
client.print(" %\t");
client.println("</H1>");
client.println("<p />");
client.println("<H2>");
client.print("Temperature: ");
client.println("</H2>");
client.println("<H1>");
client.print(t*1.8+32);
client.println(" °");
client.println("F");
client.println("</H1>");
client.println("</html>");
break;
}
if (c == '\n') {
// you're starting a new line
currentLineIsBlank = true;
}
else if (c != '\r') {
// you've gotten a character on the current line
currentLineIsBlank = false;
}
}
}
// give the web browser time to receive the data
delay(1);
// close the connection:
client.stop();
Serial.println("client disonnected");
}
}
Step 4: Barometric Pressure
We have added the BMP-085 / BMP180 Barometric Pressure Sensor, and the calculations for Heat Index and Dew point. The Barometric Pressure Sensor has 4 connections, SDA (A4), SCL (A5), Gnd, and VIN (5vdc). See http://arduinotronics.blogspot.com/2014/02/sensing-barometric-pressure.html for details.
The Adafruit BMP-180 is shown below, but have also tested with the ICStation BMP-085. No changes to code or circuit. See http://arduinotronics.blogspot.com/2014/02/icstation-5v-bmp-085-pressure.html
Here is the code with all the additions:
#include <Wire.h>
#include <Adafruit_BMP085.h>
float Tc=0;
float Tf=0;
float Pa=0;
float InHg=0;
float Am=0;
float Af=0;
#include "DHT.h"
#define DHTPIN 2 // what pin we're connected to
// Uncomment whatever type you're using!
#define DHTTYPE DHT11 // DHT 11
//#define DHTTYPE DHT22 // DHT 22 (AM2302)
//#define DHTTYPE DHT21 // DHT 21 (AM2301)
// Connect pin 1 (on the left) of the sensor to +5V
// Connect pin 2 of the sensor to whatever your DHTPIN is
// Connect pin 4 (on the right) of the sensor to GROUND
// Connect a 10K resistor from pin 2 (data) to pin 1 (power) of the sensor
DHT dht(DHTPIN, DHTTYPE);
float tF;
float dP;
float dPF;
#include <SPI.h>
#include <Ethernet.h>
// Enter a MAC address and IP address for your controller below.
// The IP address will be dependent on your local network:
byte mac[] = {
0x90, 0xA2, 0xDA, 0x00, 0x23, 0x36 };
IPAddress ip(192,168,254,177);
// Initialize the Ethernet server library
// with the IP address and port you want to use
// (port 80 is default for HTTP):
EthernetServer server(80);
Adafruit_BMP085 bmp;
void setup() {
// Open serial communications and wait for port to open:
Serial.begin(9600);
if (!bmp.begin()) {
Serial.println("Could not find a valid BMP085 sensor, check wiring!");
while (1) {}
}
while (!Serial) {
; // wait for serial port to connect. Needed for Leonardo only
}
dht.begin();
// start the Ethernet connection and the server:
Ethernet.begin(mac, ip);
server.begin();
Serial.print("server is at ");
Serial.println(Ethernet.localIP());
}
void loop() {
Serial.print("Temperature = ");
//Serial.print(bmp.readTemperature());
Tc=bmp.readTemperature();
Tf=((Tc*9)/5)+32;
Serial.print(Tf);
Serial.println(" *F");
Serial.print("Pressure = ");
//Serial.print(bmp.readPressure());
Pa=bmp.readPressure();
InHg=Pa*0.000295333727;
Serial.print(InHg);
Serial.println(" In Hg");
// Calculate altitude assuming 'standard' barometric
// pressure of 1013.25 millibar = 101325 Pascal
Serial.print("Altitude = ");
//Serial.print(bmp.readAltitude());
Am=bmp.readAltitude(101550); //adjusted for local altitude
Af=Am*3.28084;
Serial.print(Af);
Serial.println(" feet");
// you can get a more precise measurement of altitude
// if you know the current sea level pressure which will
// vary with weather and such. If it is 1015 millibars
// that is equal to 101500 Pascals.
// Serial.print("Real altitude = ");
// Serial.print(bmp.readAltitude(101500));
// Serial.println(" meters");
Serial.println();
// Reading temperature or humidity takes about 250 milliseconds!
// Sensor readings may also be up to 2 seconds 'old' (its a very slow sensor)
float h = dht.readHumidity();
float t = dht.readTemperature();
// check if returns are valid, if they are NaN (not a number) then something went wrong!
if (isnan(t) || isnan(h)) {
Serial.println("Failed to read from DHT");
} else {
Serial.print("Humidity: ");
Serial.print(h);
Serial.print(" %\t");
Serial.print("Temperature: ");
Serial.print(t);
tF=((t*9)/5)+32;
Serial.println(" *C");
}
// listen for incoming clients
EthernetClient client = server.available();
if (client) {
Serial.println("new client");
// an http request ends with a blank line
boolean currentLineIsBlank = true;
while (client.connected()) {
if (client.available()) {
char c = client.read();
Serial.write(c);
// if you've gotten to the end of the line (received a newline
// character) and the line is blank, the http request has ended,
// so you can send a reply
if (c == '\n' && currentLineIsBlank) {
// send a standard 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("Refresh: 5"); // refresh the page automatically every 5 sec
client.println();
client.println("<!DOCTYPE HTML>");
client.println("<html>");
client.println("<TABLE>");
client.println("<TR>");
client.println("<TD>");
// output the value of the DHT-11
client.print("Humidity: ");
client.println("</TD>");
client.println("<TD>");
client.print(h);
client.print(" %\t");
client.println("</TD>");
client.println("</TR>");
client.println("<TR>");
client.println("<TD>");
client.print("Temperature: ");
client.println("</TD>");
client.println("<TD>");
client.print(t*1.8+32);
client.println(" °");
client.println("F");
client.println("</TD>");
client.println("</TR>");
client.println("<TR>");
client.println("<TD>");
client.print("Barometric Pressure: ");
client.println("</TD>");
client.println("<TD>");
client.print(InHg);
//client.println(" °");
client.println(" In.");
client.println("</TD>");
client.println("</TR>");
client.println("<TR>");
client.println("<TD>");
client.println("Dew Point: ");
client.println("</TD>");
client.println("<TD>");
dP=(dewPointFast(t, h));
dPF=((dP*9)/5)+32;
client.println(dPF);
client.println(" °");
client.println("F");
client.println("</TD>");
client.println("</TR>");
client.println("<TR>");
client.println("<TD>");
client.println("Heat Index: ");
client.println("</TD>");
client.println("<TD>");
client.println(heatIndex(tF,h));
client.println(" °");
client.println("F");
client.println("</TD>");
client.println("</TR>");
client.println("</TABLE>");
client.println("</html>");
break;
}
if (c == '\n') {
// you're starting a new line
currentLineIsBlank = true;
}
else if (c != '\r') {
// you've gotten a character on the current line
currentLineIsBlank = false;
}
}
}
// give the web browser time to receive the data
delay(1);
// close the connection:
client.stop();
Serial.println("client disonnected");
}
}
// delta max = 0.6544 wrt dewPoint()
// 6.9 x faster than dewPoint()
// reference: http://en.wikipedia.org/wiki/Dew_point
double dewPointFast(double celsius, double humidity)
{
double a = 17.271;
double b = 237.7;
double temp = (a * celsius) / (b + celsius) + log(humidity*0.01);
double Td = (b * temp) / (a - temp);
return Td;
}
double heatIndex(double tempF, double humidity)
{
double c1 = -42.38, c2 = 2.049, c3 = 10.14, c4 = -0.2248, c5= -6.838e-3, c6=-5.482e-2, c7=1.228e-3, c8=8.528e-4, c9=-1.99e-6 ;
double T = tempF;
double R = humidity;
double A = (( c5 * T) + c2) * T + c1;
double B = ((c7 * T) + c4) * T + c3;
double C = ((c9 * T) + c8) * T + c6;
double rv = (C * R + B) * R + A;
return rv;
}
Step 5: Accessing From the Outside World
Modifying the setup on your home router to allow access from the outside world is a bit beyond the focus of this instructable, but there are many tutorials on the web. What you need to do is set up Network Address Translation (NAT), so someone accessing your public IP address gets forwarded (and translated) to the private IP on your Arduino. The other step is configuring Dynamic DNS (DDNS) so that when your ISP flips your IP address, the world can still access your Arduino by name, instead of a set of changing numbers. Here is a tutorial on the subject:
http://www.noip.com/support/knowledgebase/using-no-ip-with-a-cabledsl-router/
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