salve a tutti,
sto testando uno sketch webserver che mostra tramite ajax lo stato di due pulsanti. lo sketch funziona e fin qui nessun problema.
ora però ho la necessità di fare anche alcune operazioni sulla SD (ho un arduino ethernet + IDE 1.0.1).
il problema nasce quando vado ad includere nello sketch la libreria SD.h. il compilatore non segnala nessun errore ne prima ne dopo l'inclusione della libreria, ma il risultato è alquanto strano. in pratica sulla pagina web viene ripetuto il titolo H1 e lo stato dei pulsanti appare a tratti poi viene rimpiazzato da un altro messaggio. non saprei come spiegarlo in poche parole per cui allego lo sketch se qualcuno ha voglia di provarlo. fate la prova con e senza SD.h.
#include <Ethernet.h>
#include <SPI.h>
//#include <SD.h>
byte mac[] = { 0x90, 0xA2, 0xDA, 0x0E, 0x01, 0x21 };
IPAddress ip(192, 168, 1, 199);
EthernetServer server(80);
String HTTP_req; // stores the HTTP request
void setup()
{
Ethernet.begin(mac, ip); // initialize Ethernet device
server.begin(); // start to listen for clients
Serial.begin(9600); // for diagnostics
pinMode(2, INPUT); // switch is attached to Arduino pin 2
pinMode(3, INPUT); // switch is attached to Arduino pin 3
}
void loop()
{
EthernetClient client = server.available(); // try to get client
if (client) { // got client?
boolean currentLineIsBlank = true;
while (client.connected()) {
if (client.available()) { // client data available to read
char c = client.read(); // read 1 byte (character) from client
HTTP_req += c; // save the HTTP request 1 char at a time
// last line of client request is blank and ends with \n
// respond to client only after last line received
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: keep-alive");
client.println();
if (HTTP_req.indexOf("ajax_switch") > -1) { // AJAX request for switch state
// read switch state and send appropriate paragraph text
GetSwitchState(client);
}
else { // HTTP request for web page
// send web page - contains JavaScript with AJAX calls
client.println("<!DOCTYPE html>");
client.println("<html>");
client.println("<head>");
client.println("<title>Arduino Web Page</title>");
client.println("<script>");
client.println("function GetSwitchState() {");
client.println("nocache = \"&nocache=\"\ + Math.random() * 1000000;");
client.println("var request = new XMLHttpRequest();");
client.println("request.onreadystatechange = function() {");
client.println("if (this.readyState == 4) {");
client.println("if (this.status == 200) {");
client.println("if (this.responseText != null) {");
client.println("document.getElementById(\"switch_txt\")\.innerHTML = this.responseText;");
client.println("}}}}");
client.println("request.open(\"GET\", \"ajax_switch\" + nocache, true);");
client.println("request.send(null);");
client.println("setTimeout('GetSwitchState()', 1000);");
client.println("}");
client.println("</script>");
client.println("</head>");
client.println("<body onload=\"GetSwitchState()\">");
client.println("<h1>Arduino AJAX Switch Status</h1>");
client.println("<p id=\"switch_txt\">Switch state: Not requested...</p>");
client.println("</body>");
client.println("</html>");
}
// display received HTTP request on serial port
Serial.print(HTTP_req);
HTTP_req = ""; // finished with request, empty string
break;
}
// every line of text received from the client ends with \r\n
if (c == '\n') {
// last character on line of received text
// starting new line with next character read
currentLineIsBlank = true;
}
else if (c != '\r') {
// a text character was received from client
currentLineIsBlank = false;
}
} // end if (client.available())
} // end while (client.connected())
delay(1); // give the web browser time to receive the data
client.stop(); // close the connection
} // end if (client)
}
// send the state of the switch to the web browser
void GetSwitchState(EthernetClient cl)
{
for( int pin = 2; pin < 4; pin++){
if (digitalRead( pin ) ) {
cl.println("<div id='on'> Switch ");
cl.println(pin);
cl.println(" state: ON </div>");
}
else {
cl.println("<div id='off'>Switch ");
cl.println(pin);
cl.println(" state: OFF</div>");
}
}
}