ESP8266 http GET request don't show any value in serial monitor

Question

I have a table in MySQL database inside my local server and I managed to echo that value using a PHP script. Here is the PHP script (I have named it get.php and it is directly inside my htdocs folder in xammp).

<?php
$servername = "localhost";
$username = "root";
$password = "";
$dbname = "mydb";

// Create connection
$conn = new mysqli($servername, $username, $password, $dbname);
// Check connection
if ($conn->connect_error) {
    die("Connection failed: " . $conn->connect_error);
}

$sql = "SELECT reading FROM myread";
$result = $conn->query($sql);

if ($result->num_rows > 0) {
    // output data of each row
    while($row = $result->fetch_assoc()) {
        echo $row["reading"]."<br>";
    }
} else {
    echo "0 results";
}
$conn->close();
?>

and I also tried to get that data to esp8266 using the below code

#include <ESP8266WiFi.h>
#include <WiFiClient.h>
#include <ESP8266WebServer.h>
#include <ESP8266mDNS.h>
#include <ESP8266HTTPClient.h>

int status = WL_IDLE_STATUS;
char server[] = "112.135.74.254";
char ssid[] = "MYWIFI";
char pass[] = "123654MY";
const int httpPort = 80;
float line;
float mililine;

WiFiClient client;

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

  while (status != WL_CONNECTED) {
    Serial.print("Attempting to connect to Network named: ");
    Serial.println(ssid);
    status = WiFi.begin(ssid, pass);
    delay(10000);
  }

  Serial.print("SSID: ");
  Serial.println(WiFi.SSID());
  IPAddress ip = WiFi.localIP();
  IPAddress gateway = WiFi.gatewayIP();
  Serial.print("IP Address: ");
  Serial.println(ip);


if (!client.connect(server, httpPort)) {
    Serial.println("connection failed");
    return;
  }


  String url = "/get.php";
  Serial.print("requesting URL: ");
  Serial.println(url);

  client.print(String("GET ") + url + " HTTP/1.1\r\n" +
               "Host: " + server + "\r\n" +
               "User-Agent: BuildFailureDetectorESP8266\r\n" +
               "Connection: close\r\n\r\n");



Serial.println("request sent");
  while (client.connected()) {
  String  line = client.readStringUntil('\n');
    if (line == "\r") {
      Serial.println("headers received");
      break;
    }
  }
  Serial.println("reply was:");
  Serial.println("==========");
  Serial.println(line);
  Serial.println("==========");
  Serial.println("closing connection");


 mililine= line * 0.001;
 Serial.println("Final value is - ");
 Serial.println(mililine);

}
void loop() {

}

But the problem is even my database table has a value on it (the value is 55.25, I mean it has decimal places too) Serial monitor only display output as zero Here is the Arduino serial monitor output

⸮_⸮⸮=s⸮⸮Attempting to connect to Network named: MYWIFI
Attempting to connect to Network named: MYWIFI
Attempting to connect to Network named: MYWIFI
SSID: MYWIFI
IP Address: 192.168.1.102
requesting URL: /get.php
request sent
headers received
reply was:
==========
0.00
==========
closing connection
Final value is - 
0.00

When I run get.php script in a browser it shows me the value PHP script shows the value in a browser. So I need to get this displaying value to the Arduino serial monitor. As I mentioned above it shows zero instead of this value.Any help, please ???

Have you tried running your code in loop. Serup runs once so if you do not hit the spot you will get no data. Please read about setup and loop on arduino.cc — Codebreaker007, May 02 '20 at 17:28

score 0 · Accepted Answer · answered May 03 '20 at 10:49

I reworked your code to use char arrays instead of String class and changed the decoding logic. It might have flaws though, cause i could not test the logic for your script.If its not doing what you want, uncomment getDebug() and comment getData() upload and post result (starting with ==== DEBUG ====) as edit to your question.If you get a buffersize error double the amount of BUFFERSIZE till it runs through.

/*
  Web Server

  A simple webserver getting a value from a database.

  by codebraker007
*/

#include <ESP8266WiFi.h>
#include <WiFiClient.h>
#include <ESP8266WebServer.h>
#include <ESP8266mDNS.h>
#include <ESP8266HTTPClient.h>

const uint16_t BUFFERSIZE = 256;
void sendReq();
void getData();
void getDebug();

char msgBuffer[BUFFERSIZE] = {'\0'};

int status = WL_IDLE_STATUS;
const char ssid[] = "MYWIFI";
const char pass[] = "123654MY";
// Server related vars
const char serverIp[] = "112.135.74.254";
const uint16_t httpPort = 80;
const char  url[] = "/get.php";

float mililine;

WiFiClient client;


void setup() {
  // For serial monitor
  Serial.begin(9600);
  while (!Serial) {
    ; // wait
  }

  while (status != WL_CONNECTED) {
    Serial.print("Attempting to connect to Network named: ");
    Serial.println(ssid);
    status = WiFi.begin(ssid, pass);
    delay(10000);
  }

  Serial.print("SSID: ");
  Serial.println(WiFi.SSID());
  IPAddress ip = WiFi.localIP();
  IPAddress gateway = WiFi.gatewayIP();
  Serial.print("IP Address: ");
  Serial.println(ip);
  Serial.print("Gateway IP Address: ");
  Serial.println(gateway);


  if (!client.connect(serverIp, httpPort)) {
    Serial.println("connection failed");
    return;
  }
  while (client.connected()) {
    sendReq();
    getData();
    //getDebug();
  }

}


void loop() {

}

void sendReq() {
  Serial.print("requesting URL: ");
  Serial.println(url);
  strcpy ( msgBuffer, "GET ");
  strcat ( msgBuffer, url);
  strcat ( msgBuffer, " HTTP/1.1\r\n" );
  strcat ( msgBuffer,  "Host: ");
  strcat ( msgBuffer, serverIp);
  strcat ( msgBuffer, "\r\n");
  strcat ( msgBuffer, "User-Agent: BuildFailureDetectorESP8266\r\n");
  strcat ( msgBuffer, "Connection: close\r\n\r\n");

  client.print(msgBuffer);
  Serial.println("request sent");
}

void getData() {
  bool isHeader = true;
  uint16_t i = 0;
  msgBuffer[0] = '\0';
  if (client.available()) {
    if (i >= BUFFERSIZE) {
      Serial.println("==== DATA READ ERROR ====  /n Enlarge buffer size");
      return;
    }
    char c = client.read();
    if (c != '\r') {
      if (c == '\n' && isHeader ) {
        Serial.println("header received ");
        Serial.println("reply was:");
        Serial.println("==========");
        Serial.println(msgBuffer);
        i = 0;
        msgBuffer[i] = '\0';
        isHeader = false;
      }
      else if (c == '\n' && !isHeader ) {
        Serial.println(msgBuffer);
        Serial.println("==========");

        mililine = atof(msgBuffer) * 0.001;
        Serial.println("Final value is - ");
        Serial.println(mililine);
        Serial.println("==========");
        msgBuffer[i] = '\0';
        i = 0;
      }
      else if ( c != '\n' ) {
        msgBuffer[i] = c;
        i++;
      }
    } //  '\r'
  } // client available
}



void getDebug() {
  uint16_t i = 0;
  msgBuffer[0] = '\0';
  if (client.available()) {
    if (i >= BUFFERSIZE) {
      Serial.println("==== DEBUG ERROR ====  /n Enlarge buffer size");
      return;
    }
    char c = client.read();
    if (c == '\r') {
      msgBuffer[i] = '/';
      i++;
      msgBuffer[i] = 'r';
      i ++;
    }
    else if (c == '\n') {
      msgBuffer[i] = '/';
      i++;
      msgBuffer[i] = 'n';
      i ++;
    }
    else {
      msgBuffer[i] = c;
      i++;
    }
  } // client available
  Serial.println("==== DEBUG ====");
  Serial.println(msgBuffer);
  Serial.println("==========");
}

ESP8266 http GET request don't show any value in serial monitor

1 Answers1