Embedded Files
Parts and components
Parts and components
- An Arduino
- DHT11 or DHT22 sensor from Adafruit or various ebay vendors
- 10K resistor for the DHT11 pullup
- 16x2 LCD display HD44780
- 10k trimpot for LCD contrast
- 100 Ohm resistor for the LCD backlight
- ENC26J60 Ethernet module or shield
- Prototype shield if you use a regular Arduino and ENC28J60 Ethernet shield
- hookup wire, breadboard etc for prototyping
I wanted them to be able to check the temperature and humidity of the room both by checking an LCD display in the room and also via a web page. I put together an Arduino with a DHT11 sensor, 16x2 LCD display and ENC28J60 Ethernet module
Arduino Code:
// DHT code from:
// Example testing sketch for various DHT humidity/temperature sensors
// Written by ladyada, public domain
#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)
DHT dht(DHTPIN, DHTTYPE);
// LCD RS=3, EN=4, DS4=5, DS5=6, DS6=7, DS7=8
#include <LiquidCrystal.h>
LiquidCrystal lcd( 3, 4, 5, 6, 7, 8);
// EtherCard code from the RBBB Example
// This is a demo of the RBBB running as webserver with the Ether Card
// 2010-05-28 <jc@wippler.nl> http://opensource.org/licenses/mit-license.php
#include <EtherCard.h>
// ethernet interface mac address, must be unique on the LAN
static byte mymac[] = { 0x74,0x69,0x69,0x2D,0x30,0x31 };
static byte myip[] = { 192,168,3,177 };
static byte gwip[] = { 192,168,3,1 };
byte Ethernet::buffer[500];
BufferFiller bfill;
// Global Variables Defined
// This is so we can see them in all functions
// t is the temperature, h is the humidity
// Timer is used to reduce the frequency of reading the DHT11 - I found reading it every loop
// caused timing issues with the Ethernet.
// The Animation loop is to provide some bling to the LCD diaplay
int t=0;
int h=0;
int Timer= 0;
int Animation = 0;
// Setup - bring Ethernet, LCD and DHT11 live
void setup () {
if (ether.begin(sizeof Ethernet::buffer, mymac, 10) == 0)
Serial.println( "Failed to access Ethernet controller");
ether.staticSetup(myip, gwip);
lcd.begin(16,2);
dht.begin();
}
// Here we get values from the DHT11
static void ReadDHT11()
{
h = dht.readHumidity();
t = dht.readTemperature();
}
// Here we build a web page and pass the t and h values into it
static word homePage() {
//ReadDHT11();
bfill = ether.tcpOffset();
bfill.emit_p(PSTR(
"HTTP/1.0 200 OK\r\n"
"Content-Type: text/html\r\n"
"Pragma: no-cache\r\n"
"\r\n"
"<meta http-equiv='refresh' content='30'/>"
"<title>Temp server</title>"
"<h1>Temp: $D C <br>Humidity: $D %</h1>"),
t, h);
return bfill.position();
}
// The main loop
// We add to the timer and read the DHT11 values when Timer == 1, otherwise we loop without reading it
// Once the Timer value == to 1100 we zero it and start the count again. This way the sensors are only
// read once every 1100 loops. Every time we go through the loop we listen for a request on the Ethernet
// If we see one we send the webpage. We also add an animation on the LCD so we know the loop is working.
void loop () {
Timer = Timer+1;
if(Timer==1)
{
ReadDHT11();
// set the cursor to (0,0):
lcd.setCursor(0, 0);
// print from 0 to 9:
lcd.print("Temp: ");
lcd.print(t);
lcd.print("C");
// set the cursor to (16,1):
lcd.setCursor(0,1);
lcd.print("Humidity: ");
lcd.print(h);
lcd.print("%");
if(Animation==0)
{
lcd.print(" *");
}
if(Animation==1)
{
lcd.print(" +");
}
Animation = Animation + 1;
if(Animation==2)
{
Animation=0;
}
}
if(Timer==1100)
{
Timer=0;
}
word len = ether.packetReceive();
word pos = ether.packetLoop(len);
if (pos) // check if valid tcp data is received
{
ReadDHT11();
ether.httpServerReply(homePage()); // send web page data
}
}
Link: http://www.instructables.com/id/Arduino-TempHumidity-with-LCD-and-Web-Interface/
Link : Library :EtherCard.h
https://github.com/jcw/ethercard
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