How To Control Arduino From Mobile Phone

/*
 PROCE55 WiFi Server Example with JSON request parser
 */
 
#include <SPI.h>
#include <WiFi.h>
#include <LiquidCrystal.h>
    
char ssid[] = "P55";      // your network SSID (name)
char pass[] = "PROCE55mobile";  // your network password
//char ssid[] = "EG1";      // your network SSID (name)
//char pass[] = "XML4SDXML4SD1";  // your network password
//char ssid[] = "Tech_D0047758";      // your network SSID (name)
//char pass[] = "WBTJZXJU";  // your network password
// int keyIndex = 0;            // your network key Index number (needed only for WEP)
IPAddress ip(192, 168, 0, 90); // static IP for WiFi shield if needed

int status = WL_IDLE_STATUS;
WiFiServer server(80);          // Listen on tcp port 80
          
// initialize the library with the numbers of the interface pins
// LiquidCrystal lcd(12, 11, 5, 4, 3, 2);
LiquidCrystal lcd(4, 9, 5, 8, 3, 2); // 13 instead of 4 (4,7,10,11 and 12 used by Wifi Shield)

void setup() {
  //Serial.begin(9600);      // initialize serial communication - comment out for better perfomance
  //while (!Serial) {
    // wait serial port initialization
  //}
  
  //pinMode(10, OUTPUT);      // HDG204 WiFi deactivate SD card pin 10, if necessary
  //digitalWrite(10, HIGH);

  // Turn of the LED by default
  pinMode(6, OUTPUT);
  digitalWrite(6, LOW);
  
  //pinMode(LED_BUILTIN, OUTPUT);
  //digitalWrite(LED_BUILTIN, LOW);

  // Init the LCD 16x2
  lcd.begin(16, 2);
  lcd.clear();
 
  // check for the presence of the shield:
  if (WiFi.status() == WL_NO_SHIELD) {
    //Serial.println("WiFi shield not present");
    lcd.clear();
    lcd.setCursor(0, 1);
    lcd.print(F("Error: no wifi!"));
    while (true);       // don't continue
  }

  /*
  if (WiFi.firmwareVersion() != "1.1.0") {
    Serial.println(F("Please upgrade the WiFi Shield firmware!"));
    lcd.clear();
    lcd.setCursor(0, 1);
    lcd.print(F("Firmware old!"));
  }
  */
  
  // attempt to connect to Wifi network:
  lcd.clear();
  lcd.setCursor(0, 0);
  lcd.print(F("Initializing..."));
  lcd.setCursor(0, 1);
  lcd.print(F("SSID:"));
  lcd.setCursor(5, 1);
  lcd.print(ssid);

  // Comment the WiFi.config if static setup not needed, DHCP applies then
  //WiFi.config(ip); // WiFi.config(ip, dns, gateway, subnet);  
   
  while (status != WL_CONNECTED) {
    //Serial.print(F("Attempting to connect to WLAN SSID: "));
    //Serial.println(ssid);                   // print the network name (SSID);  
    status = WiFi.begin(ssid, pass);
    // wait 6 seconds for connection:
    delay(6000);
  }
  server.begin();                           // start the web server on port 80
                         
  lcd.clear();
  lcd.setCursor(0, 0);
  lcd.print("Ready");
  printWifiStatus();
}

void loop() {
  WiFiClient client = server.available();   // listen for incoming clients
  
  if (client) {
    //Serial.print(F("Client connected"));
    String req_str = "";
    String currentLine = "";
    int data_length = 0;
    int data_read_length = 0;
    boolean skip = true; // Skip first CRLF in request header
    int response_length = 0; // HTTP response Content-Length
    int resp_value = -1;  // LED status
    
    lcd.clear(); lcd.setCursor(0, 0); lcd.print(F("Client")); lcd.setCursor(0, 1); lcd.print(F("connected"));
  
    while (client.connected()) 
    {
      if (client.available()) {
        char c = client.read();
        //Serial.write(c);
    
        if (data_length > data_read_length && !skip) {
          // Read remaining request body data
          req_str += c;
          data_read_length++;
          //Serial.println(data_read_length);
        }
        
        if (data_length <= data_read_length && !skip) { // c == '\n' &&
          // Request read completed, send response
               
          // find the request commands manually based on a substring
          if (req_str.lastIndexOf("\"OFF\"") >= 0) {
            digitalWrite(6, LOW);  
            resp_value = 0;
            //Serial.println(F("\r\n===> Setting LED off..."));
          }
          else if (req_str.lastIndexOf("\"ON\"") >= 0) {
            digitalWrite(6, HIGH);  
            resp_value = 1;
            //Serial.println(F("\r\n===> Setting LED on...")); 
          }
          else {
            // GET
            if (digitalRead(6) == 1) {
              resp_value = 1; // HIGH
             }
             else {
              resp_value = 0;  // LOW
             }
          }
          
          // Send the response
          //Serial.println(F("===> Request read completed, sending response..."));

          response_length = 56; // = 51 + 1 + 4;
          
          client.write("HTTP/1.1 200 OK\r\n");
          client.write("Content-Length: ");
          client.print(response_length); // sizeof(resp)
          client.write("\r\n");
          client.write("Connection: close\r\n");
          client.write("Access-Control-Allow-Origin: *\r\n");
          client.write("Content-type: application/json; charset=utf-8\r\n");
          client.write("\r\n");
          client.write("{\"Parameters\":[{\"ParamName\":\"STATUS\",\"ParamValue\":\""); // 51 characters
          client.print(resp_value); // 1 character
          client.write("\"}]}"); // 4 characters
          client.write("\r\n");
          break;
        }
        else if (c == '\n' && currentLine.length() == 0 && skip) {
          // Start of the request body after this line
          //Serial.println(F("===> Start of the request body."));
          skip = false;
        }
        else if (c == '\n' && currentLine.length() > 15 && currentLine.startsWith(F("Content-Length:")) && skip) {
          //skip = false;
          //String temp = currentLine.substring(15);
          //temp.trim();
          //Serial.print(F("===> Content length detected: "));
          //data_length = temp.toInt();
          data_length = currentLine.substring(15).toInt();
          //Serial.println("Content-length: ");
          //Serial.println(data_length);
        }

        if (c == '\n') {
          // new line
          currentLine = "";
        } else if (c != '\r') {
          // add current character to the current line
          currentLine += c;
        }
        
      } // if data available
    } // client still connected
    
    // give the client time to receive the data
    delay(50);
    // close the connection:
    client.stop();
    //Serial.println(F("===> Client disconnected."));
    printWifiStatus();
  }
}

/*
POST / HTTP/1.1
Content-Length: 328
Content-Type: application/json

{"FunctionName":"TEST","Status":"","StatusText":"","TextEncoding":"","SecurityToken":"","Parameters":[{"ParamName":"function_name","ParamValue":"TEST"},{"ParamName":"requestencoding","ParamValue":"UTF-8"},{"ParamName":"responseencoding","ParamValue":"UTF-8"},{"ParamName":"PARAM1","ParamValue":"Test passed!"}],"TableValues":[]}
  
  */
  
void printWifiStatus() {
  // print the SSID of the network you're attached to:
  Serial.print(F("SSID: "));
  Serial.println(WiFi.SSID());

  // print your WiFi shield's IP address:
  IPAddress ip = WiFi.localIP();
  Serial.print(F("IP Address: "));
  Serial.println(ip);
  
  // Status to LCD
  lcd.clear();
  lcd.setCursor(0, 0);
  lcd.print(WiFi.SSID());
  
  lcd.setCursor(0, 1);
  lcd.print(IpAddress2String(ip));
  
  // print the received signal strength:
  Serial.print(F("Signal strength (RSSI):"));
  Serial.print(WiFi.RSSI());
  Serial.println(F(" dBm"));
  // print where to go in a browser:
  Serial.print(F("Send your HTTP requests to http://"));
  Serial.println(ip);
  return;
}

String IpAddress2String(const IPAddress& ipAddress)
{
  return String(ipAddress[0]) + String(".") +\
  String(ipAddress[1]) + String(".") +\
  String(ipAddress[2]) + String(".") +\
  String(ipAddress[3])  ; 
}