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;
}
?>

• Majenko: Step 1: confirm if the request is reaching the Apache server.
• Filipe Carrasquinho: Sorry the delay but I just saw it now... Yes the request is reaching the server. I tried with a simpler code just to be sure and the server sends a response, but not what I want. It seems that the $_GET['temp'] is not set...
• Majenko: php/?temp - That looks "iffy" to me. Should that / be in there?
• Filipe Carrasquinho: I think so, just a while ago I spoted an error in that line I had "php/?$temp" in there and solved part of my problem. It seems like the problem is that the $_SESSION can't be reached. And besides that my web page on the browser dosen't react
• Majenko: $_SESSION either needs cookies or a PHPSESSID=.... parameter, neither of which you will likely have.

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.