Ethernet communication issue

Projects Networking, Protocols, and Devices
1

Hi. A query. An arduino with an ethernet module where there is a small "server" where one in the web browser puts the IP of the arduino and shows you a page. This page if you click on a button turns on the led on the arduino, and if clicking on another button turns off the led. when one presses the button, technically it makes a redirect or a GET to /? LED = T leaving 192.168.1.7/?LED=T which would make the led turn on. The same by directly placing that url in the browser, and to turn it off 192.168.1.7/?LED=F.

This gives me the possibility to create an android app that when pressing the button sends that request "192.168.1.7/?LED=T"

Now .. how can I make it from another arduino board with a module, simulate that I am pressing that button? for example, that the second arduino is sending every 5 seconds the command "192.168.1.7/?LED=T" to turn on the led, and after 5 seconds to turn it off. I do not know how to do that.

I want to do it like this and not by tcp / udp. it's possible? because it would serve me for future projects that behave like this.

#include <SPI.h> 
#include <Ethernet.h> 
byte mac[]={0xDE,0xAD,0xBE,0xEF,0xFE,0xED}; 
IPAddress ip(192,168,1,7); 
EthernetServer servidor(80); 

int PIN_LED=8; 
String readString=String(30);
String state=String(3);


void setup() {
  Ethernet.begin(mac, ip); 
  servidor.begin(); 
  pinMode(PIN_LED,OUTPUT);
  digitalWrite(PIN_LED,LOW);
  state="OFF";
}


void loop() {
  EthernetClient cliente= servidor.available();
  if(cliente) {
    boolean lineaenblanco=true;
    while(cliente.connected()) {
      if(cliente.available()) {
        char c=cliente.read();
        if(readString.length()<30) {
          readString.concat(c);
        }
        if(c=='\n' && lineaenblanco) 
          {
          int LED = readString.indexOf("LED=");
          if(readString.substring(LED,LED+5)=="LED=T") {
              digitalWrite(PIN_LED,HIGH);
              state="ON"; }
          else if (readString.substring(LED,LED+5)=="LED=F") {
              digitalWrite(PIN_LED,LOW);
              state="OFF";
          }
   
//Cabecera HTTP estándar
cliente.println("HTTP/1.1 200 OK");
cliente.println("Content-Type: text/html");
cliente.println(); //Página Web en HTML
cliente.println("<html>");
cliente.println("<head>");
cliente.println("<title>LED ON/OFF</title>");
cliente.println("</head>");
cliente.println("<body width=100% height=100%>");
cliente.println("<center>");
cliente.println("<h1>LED ON/OFF</h1>");
cliente.print("

");
cliente.print("Estado del LED: ");
cliente.print(state);
cliente.print("



");
cliente.println("<input type=submit value=ON style=width:200px;height:75px onClick=location.href='./?LED=T\'>");
cliente.println("<input type=submit value=OFF style=width:200px;height:75px onClick=location.href='./?LED=F\'>");
cliente.println("</center>");
cliente.println("</body>");
cliente.println("</html>");
cliente.stop();
readString="";
}
}
}
}
}
2

So, you are asking how you can make one Arduino use the webpage of another Arduino using the HTTP protocol? You want to use a protocol that was invented to show humans pretty pages which they can view on a big screen and then click with a mouse or touch gently on a tablet screen?

What you need to search for is HTTP client. Maybe this will help.

If you wonder whether there are protocols that might be better suited for this kind of applications, you could look into MQTT. It well supported on Arduinos, Raspberry Pi, PCs and cloud platforms.

3

"Now .. how can I make it from another arduino board with a module, simulate that I am pressing that button? for example, that the second arduino is sending every 5 seconds the command "192.168.1.7/?LED=T" to turn on the led, and after 5 seconds to turn it off. I do not know how to do that."

You probably could put an LED toggle function in the LED server code, and a toggle trigger in a web page that meta refreshes every 5 seconds.