Receiving a HTTP POST Request on Arduino

Question

Is it possible to receive a HTTP Post request with my Arduino Uno using a Ethernet shield. I want to make an Android app wich can control me Arduino and I thought the best way t

Answer 1

Not sure about POST, but GET definitely works. Here's an AJAX example that I've been using that works. It just controls an RGB LED.

 xmlhttp.open("GET", "http://ipAddressOfArduino?r=" + redVal + "&g=" + greenVal + "&b=" + blueVal + "&e", true);

Then on the Arduino side, I just parse the data.

//ARDUINO 1.0+ ONLY
//ARDUINO 1.0+ ONLY


#include 
#include 
boolean reading = false;
String myStr;
int redVal, greenVal, blueVal;

////////////////////////////////////////////////////////////////////////
//CONFIGURE
////////////////////////////////////////////////////////////////////////
  //byte ip[] = { 192, 168, 0, 1 };   //Manual setup only
  //byte gateway[] = { 192, 168, 0, 1 }; //Manual setup only
  //byte subnet[] = { 255, 255, 255, 0 }; //Manual setup only

  // if need to change the MAC address (Very Rare)
  byte mac[] = { 0x00, 0x00, 0x00, 0x00, 0x00, 0x00 };

  EthernetServer server = EthernetServer(80); //port 80
////////////////////////////////////////////////////////////////////////

void setup(){
  Serial.begin(9600);

  pinMode(3, OUTPUT);
  pinMode(5, OUTPUT);
  pinMode(6, OUTPUT);

  Ethernet.begin(mac);
  //Ethernet.begin(mac, ip); //for manual setup

  server.begin();
  Serial.println(Ethernet.localIP());

}

void loop(){

  // listen for incoming clients, and process qequest.
  checkForClient();

}

void checkForClient(){

  EthernetClient client = server.available();

  if (client) {

    // an http request ends with a blank line
    boolean currentLineIsBlank = true;
    boolean sentHeader = false;
    myStr = "";
    while (client.connected()) {
      if (client.available()) {

        char c = client.read();

        if(reading && c == ' ') reading = false;
        if(c == '?') reading = true; //found the ?, begin reading the info

        if(reading){
          //Serial.print(c);
          if (c!='?') {
            myStr += c;
          }

        }

        if (c == '\n' && currentLineIsBlank)  break;

        if (c == '\n') {
          currentLineIsBlank = true;
        }else if (c != '\r') {
          currentLineIsBlank = false;
        }
      }
    }

    parseThangs(myStr);
    analogWrite(3, redVal);
    analogWrite(5, greenVal);
    analogWrite(6, blueVal);    
    delay(100); // give the web browser time to receive the data
    client.stop(); // close the connection:    
  } 
}

void parseThangs(String str) {
  int startIndex = str.indexOf("r");
  int endIndex = str.indexOf("g");
  String redStr = str.substring(startIndex + 2, endIndex - 1);
  char tempRed[4];
  redStr.toCharArray(tempRed, sizeof(tempRed));
  redVal = atoi(tempRed);
  startIndex = str.indexOf("g");
  endIndex = str.indexOf("b");
  String greenStr = str.substring(startIndex + 2, endIndex -1);
  char tempGreen[4];
  greenStr.toCharArray(tempGreen, sizeof(tempGreen));
  greenVal = atoi(tempGreen);
  startIndex = str.indexOf("b");
  endIndex = str.indexOf("e");
  String blueStr = str.substring(startIndex + 2, endIndex -1);
  char tempBlue[4];
  blueStr.toCharArray(tempBlue, sizeof(tempBlue));
  blueVal = atoi(tempBlue);
  Serial.println(redStr + " " + greenStr + " " + blueStr);
}

Probably a little sloppy, but it works.