Updated! Arduino Ethernet code
Since last Arduino Ethernet code there we several Arduino IDE releases with changes that affected the code listed in this post. Due high interest, we updated it with minor changes that makes it work as expected. The biggest occurred because Wstring.h library isn’t no longer in use, because String.h library is included in core that brings some difference in several functions used in code.
In code we need to write
readString += c; instead readString.append(c);
if(readString.indexOf(“L=1″) >0) instead if(readString.contains(“L=1″))
Also we need to re-import Ethernet.h library in order to bring along all necessary libraries like Client.h, Server.h, SPI.h, Udp.h.
The other problem occurred when program run was that LED actually never lights up when checkbox is selected. I used Serial.print(c); to track down the problem. And it seems that method GET sends two strings:
Our code was catching and analyzing both strings. We only need to take string where parameter is sent: “GET /?L=1 HTTP/1.1” and skip “GET /favicon.ico HTTP/1.1”. As our example is very simple we can see ,that second string lacks “?” symbol. So we check the string if there is a ‘?’ symbol, of not, skip whole analyze.
And last fix is applied to LED checkbox. Now it stays checked if LED is ON. Hope you find these changes useful.
Here is a code listing:
#include <SPI.h>
#include <Client.h>
#include <Ethernet.h>
#include <Server.h>
#include <Udp.h>
byte mac[] = { 0xDE, 0xAD, 0xBE, 0xEF, 0xFE, 0xED }; //physical mac address
byte ip[] = { 192, 168, 0, 110 }; // ip in lan
byte gateway[] = { 192, 168, 0, 1 }; // internet access via router
byte subnet[] = { 255, 255, 255, 0 }; //subnet mask
Server server(80); //server port
byte sampledata=50; //some sample data - outputs 2 (ascii = 50 DEC)
int ledPin = 4; // LED pin
char link[]="http://www.scienceprog.com/"; //link data
String readString = String(30); //string for fetching data from address
boolean LEDON = false; //LED status flag
void setup(){
//start Ethernet
Ethernet.begin(mac, ip, gateway, subnet);
//Set pin 4 to output
pinMode(ledPin, OUTPUT);
//enable serial datada print
Serial.begin(9600);
}
void loop(){
// Create a client connection
Client client = server.available();
if (client) {
while (client.connected()) {
if (client.available()) {
char c = client.read();
//read char by char HTTP request
if (readString.length() < 100)
{
//store characters to string
readString += c; //replaces readString.append(c);
}
//output chars to serial port
Serial.print(c);
//if HTTP request has ended
if (c == '\n') {
//dirty skip of "GET /favicon.ico HTTP/1.1"
if (readString.indexOf("?") <0)
{
//skip everything
}
else
//lets check if LED should be lighted
if(readString.indexOf("L=1") >0)//replaces if(readString.contains("L=1"))
{
//led has to be turned ON
digitalWrite(ledPin, HIGH); // set the LED on
LEDON = true;
}else{
//led has to be turned OFF
digitalWrite(ledPin, LOW); // set the LED OFF
LEDON = false;
}
// now output HTML data starting with standart header
client.println("HTTP/1.1 200 OK");
client.println("Content-Type: text/html");
client.println();
//set background to yellow
client.print("<body style=background-color:yellow>");
//send first heading
client.println("<font color='red'><h1>HTTP test routines</font></h1>");
client.println("<hr />");
client.println("<hr />");
//output some sample data to browser
client.println("<font color='blue' size='5'>Sample data: ");
client.print(sampledata);//lets output some data
client.println("<br />");//some space between lines
client.println("<hr />");
//drawing simple table
client.println("<font color='green'>Simple table: ");
client.println("<br />");
client.println("<table border=1><tr><td>row 1, cell 1</td><td>row 1, cell 2</td></tr>");
client.println("<tr><td>row 2, cell 1</td><td>row 2, cell 2</td></tr></table>");
client.println("<br />");
client.println("<hr />");
//printing some link
client.println("<font color='blue' size='5'>Link: ");
client.print("<a href=");
client.print(link);
client.println(">Visit Scienceprog!</a>");
client.println("<br />");
client.println("<hr />");
//controlling led via checkbox
client.println("<h1>LED control</h1>");
//address will look like http://192.168.1.110/?L=1 when submited
if (LEDON)
client.println("<form method=get name=LED><input type=checkbox name=L value=1 CHECKED>LED<br><input type=submit value=submit></form>");
else
client.println("<form method=get name=LED><input type=checkbox name=L value=1>LED<br><input type=submit value=submit></form>");
client.println("<br />");
//printing LED status
client.print("<font size='5'>LED status: ");
if (LEDON)
client.println("<font color='green' size='5'>ON");
else
client.println("<font color='grey' size='5'>OFF");
client.println("<hr />");
client.println("<hr />");
client.println("</body></html>");
//clearing string for next read
readString="";
//stopping client
client.stop();
}
}
}
}
}
And you can download Arduino sketch ethtest.
