How can an Arduino Mega 2560+Wifi Shield 2.0 (SeeedStudio) receive data from database in a XAMPP server on my PC?

Question

I'm trying to connect my Arduino Mega via Wifi to my XAMPP server. My main objective is get a value from my database and store it on a variable in Arduino code. With this new variable I'll be able to control the rest of the program... So I need your help. Can someone give me advice?

I already tried every thing that I found on the internet but it just doesn't work.

I think that the simple way is to send a GET request to the server and read its response... But for some reason I can't send a GET request through...

I tested it on the browser directly and the value shows up, so I think that the server side is all right.

Here is my Arduino code:

#include <Arduino.h>
#include <SoftwareSerial.h>
#include "WiFly.h"
#include "HTTPClient.h"

#define SSID      "mySSID"
#define KEY       "myKEY"
#define AUTH      WIFLY_AUTH_WPA2_PSK
#define HTTP_GET_URL "http://192.168.1.80/xampp/training/send_data_db.php/?temp=0"

// Pins' connection
// Arduino       WiFly
//  2    <---->    TX
//  3    <---->    RX
SoftwareSerial uart(10, 11);
WiFly wifly(uart);
HTTPClient http;
char get;

void setup() {
  Serial.begin(9600);
  Serial.println("------- WIFLY HTTP --------");
  uart.begin(9600); // WiFly UART Baud Rate: 9600
  // Wait WiFly to init
  //  delay(3000);

  // check if WiFly is associated with AP(SSID)
  if (!wifly.isAssociated(SSID)) {
    while (!wifly.join(SSID, KEY, AUTH)) {
      Serial.println("Failed to join " SSID);
      Serial.println("Wait 0.1 second and try again...");
      delay(100);
    }
    wifly.save(); // save configuration,
  }
  Serial.println("\r\nTry to get url - " HTTP_GET_URL);
  Serial.println("------------------------------");
  while (http.get(HTTP_GET_URL, 10000) < 0) {
  }
  while (wifly.receive((uint8_t *)&get, 1, 1000) == 1) {
    Serial.print(get);
  }
  if (wifly.commandMode()) {
    Serial.println("\r\n\r\nEnter command mode. Send \"exit\"(with \\r) to exit command mode");
  }
}

void loop() {
  int c;
  while (wifly.available()) {
    c = wifly.read();
    if (c > 0) {
      Serial.write((char)c);
    }
  }
  while (Serial.available()) {
    c = Serial.read();
    if (c >= 0) {
      wifly.write((char)c);
    }
  }
}

And here is my PHP code:

<? php
include("./connection/database_connect.php");
include("./top_table.php");

if ((isset($_SESSION["ID"])) AND (isset($_GET["temp"]))) {
  $id = $_SESSION["ID"];
  $sql = "SELECT temp FROM perfil, client WHERE perfil.ID ='$id'";
  $consult = mysqli_query($connect, $sql);
  $result = mysqli_num_rows($consult);
  if (($result == 1)) {
    $person_data = mysqli_fetch_array($consult, MYSQLI_ASSOC);
    $temp = $person_data["temp"];
    header("HTTP/1.1" . " " . 200 . "OK");
    header("Content-Type: text/html; charset=UTF-8");
    header("Content-Length: 1112");
    header("Connection: close");
    header("/r/n");
    echo $temp;
  } else {
    //se user dosen't exist on data base
    header("Location: http://192.168.1.80/xampp/training/login.php");
    exit;
  }
} else {
  header("Location: http://192.168.1.80/xampp/training/login.php");
  exit;
}
?>

Answer 1

You should forget about the $_SESSION["ID"]; on PHP side, because you are working stateless without any session! You should give a parameter for identifying your variable from arduino to php script - is this the temp=0? If so you need to exchange

$sql="SELECT temp FROM perfil, client WHERE perfil.ID ='$id'";

with

$sql="SELECT temp FROM perfil, client WHERE perfil.ID =" . $_GET["temp"];

assuming that perfil.id is only an integer - if it is a string, then add "'".

Answer 2

Yes you are right!

Meanwhile i finished this project.

The problem was with the Wi-Fi shield that I was using. The Http request wasn't in a right format.