Sending Data from ESP8266 to PHP

Question

I want to display the RFID tag value to a html file.

I am using ESP8266 ESP-01 module, EM-18 Reader Module, Arduino Uno and Xampp for hosting PHP.

Right now, I am getting a value of "255" in Arduino whenever I scan a RFID tag. But I am supposed to get the 12-digit alphanumeric RFID tag value.

I have attached the Arduino and also the output screen of the Serial Monitor.

I have my college submission next week so it's urgent. Any help would be appreciated.

#include "SoftwareSerial.h"
String ssid ="Home";
String password="****";
SoftwareSerial esp(2, 3);// RX, TX
String data;
String server = "192.168.0.182"; // www.example.com
String uri = "/testget.php";// our example is /esppost.php
int DHpin = 0;//sensor pin
byte dat [12];
String tag;

void setup() {
  pinMode (DHpin, OUTPUT);
  esp.begin(9600);
  Serial.begin(9600);
  reset();
  connectWifi();
}

//reset the esp8266 module

void reset() {
  esp.println("AT+RST");
  delay(1000);
  if(esp.find("OK") ) 
    Serial.println("Module Reset");
}

//connect to your wifi network

void connectWifi() {
  String cmd = "AT+CWJAP=\"" +ssid+"\",\"" + password + "\"";
  esp.println(cmd);
  delay(4000);
  /*
  if(esp.find("OK")) {
    Serial.println("Connected!");
  }
  else {
    connectWifi();
    Serial.println("Cannot connect to wifi"); }*/
} 

byte read_data () {
  byte data;
  for (int i = 0; i < 13; i ++) {
    if (digitalRead (DHpin) == LOW) {
      while (digitalRead (DHpin) == LOW); // wait for 50us
        delayMicroseconds (30); // determine the duration of the high level to determine the data is '0 'or '1'
      if (digitalRead (DHpin) == HIGH)
        data |= (1 << (12-i)); // high front and low in the post
      while (digitalRead (DHpin) == HIGH);
// data '1 ', wait for the next one receiver
    }
  } 
  return data; 
}

void start_test () {
  digitalWrite (DHpin, LOW); // bus down, send start signal
  delay (30); // delay greater than 18ms, so DHT11 start signal can be detected
  digitalWrite (DHpin, HIGH);
  delayMicroseconds (40); // Wait for DHT11 response
  pinMode (DHpin, INPUT);
  while (digitalRead (DHpin) == HIGH);
    delayMicroseconds (80);
  // DHT11 response, pulled the bus 80us
  if (digitalRead (DHpin) == LOW);
    delayMicroseconds (80);
  // DHT11 80us after the bus pulled to start sending data
  for (int i = 0; i < 13; i ++)
    // receive tag value data, the parity bit is not considered
    dat[i] = read_data ();
  pinMode (DHpin, OUTPUT);
  digitalWrite (DHpin, HIGH);
  // send data once after releasing the bus, wait for the host to open the next Start signal
}

void loop () {
  start_test ();
  // convert the bit data to string form
  tag= String(dat[12]);
  data = "tag=" + tag;// data sent must be under this form //name1=value1&name2=value2.
  Serial.println(data);
  httppost();
  delay(1000);
}

void httppost () {
  esp.println("AT+CIPSTART=\"TCP\",\"" + server + "\",80");//start a TCP connection.
  if( esp.find("OK")) {
    Serial.println("TCP connection ready");
  } 
  delay(1000);
  String postRequest =
  "POST " + uri + " HTTP/1.0\r\n" +
  "Host: " + server + "\r\n" +
  "Accept: *" + "/" + "*\r\n" +
  "Content-Length: " + data.length() + "\r\n" +
  "Content-Type: application/x-www-form-urlencoded\r\n" +
  "\r\n" + data;
  String sendCmd = "AT+CIPSEND=";//determine the number of caracters to be sent.
  esp.print(sendCmd);
  esp.println(postRequest.length() );
  delay(500);
  if(esp.find(">")) { 
    Serial.println("Sending.."); 
    esp.print(postRequest);
    if( esp.find("SEND OK")) { 
      Serial.println("Packet sent");
      while (esp.available()) {
        String tmpResp = esp.readString();
        Serial.println(tmpResp);
      }
      // close the connection
    esp.println("AT+CIPCLOSE");
    }
  }
}

Output :

tag= String(dat[12]); doesn't do what you think it does. Also you are trying to read 13 bytes into an array of 12 bytes and cram 13 bits into a byte. And for some reason using pin 0 for the sensor while still using serial. — gre_gor
– gre_gor, Commented Apr 13, 2018 at 17:47
Please can you help me with the code? I am new to Arduino and I'm really struggling with my grades on the line! — curiously77
– curiously77, Commented Apr 13, 2018 at 17:55
change <13 to <12 and properly convert the byte(/char) array to a String — Gerben
– Gerben, Commented Apr 13, 2018 at 18:47
I did that and I'm getting 254 now. I wrote this: String myString = String(myByteArray); to convert. — curiously77
– curiously77, Commented Apr 13, 2018 at 18:59
Your example code doesn't have myByteArray, so saying you tried that doesn't help anyone understand the context in which you tried it. You can edit your question to include updated code you have tried, etc. — jose can u c
– jose can u c, Commented Apr 13, 2018 at 19:49

curiously77 · Accepted Answer · 2018-04-13 19:56:05Z

I got it working using the code below:

#include "SoftwareSerial.h"
String ssid ="Home";

String password="%Qwerty@123%";
char input[12];        
int count = 0;  
SoftwareSerial esp(2, 3);// RX, TX

String data;

String server = "192.168.0.182"; // www.example.com

String uri = "/testget.php";// our example is /esppost.php

int DHpin = 0;//sensor pin

byte dat [12];

String temp;

void setup() {

pinMode (DHpin, OUTPUT);

esp.begin(9600);

Serial.begin(9600);

reset();

connectWifi();

}

//reset the esp8266 module

void reset() {

esp.println("AT+RST");

delay(1000);

if(esp.find("OK") ) Serial.println("Module Reset");

}

//connect to your wifi network

void connectWifi() {

String cmd = "AT+CWJAP=\"" +ssid+"\",\"" + password + "\"";

esp.println(cmd);

delay(4000);
}

byte read_data () {

byte data;

for (int i = 0; i < 8; i ++) {

if (digitalRead (DHpin) == LOW) {

while (digitalRead (DHpin) == LOW); // wait for 50us

delayMicroseconds (30); // determine the duration of the high level to determine the data is '0 'or '1'

if (digitalRead (DHpin) == HIGH){

data |= (1 << (7-i)); // high front and low in the post
 }
while (digitalRead (DHpin) == HIGH);


// data '1 ', wait for the next one receiver

}

} return data; }

void start_test () {

digitalWrite (DHpin, LOW); // bus down, send start signal

delay (30); // delay greater than 18ms, so DHT11 start signal can be detected

digitalWrite (DHpin, HIGH);

delayMicroseconds (40); // Wait for DHT11 response

pinMode (DHpin, INPUT);

while (digitalRead (DHpin) == HIGH);

delayMicroseconds (80);

// DHT11 response, pulled the bus 80us

if (digitalRead (DHpin) == LOW);

delayMicroseconds (80);
while(count<12){
input[count] = Serial.read(); // Read 1 Byte of data and store it in the input[] variable
      count++;          // increment counter
      delay(5);}
// DHT11 80us after the bus pulled to start sending data

//for (int i = 0; i < 4; i ++)

// receive temperature and humidity data, the parity bit is not considered
/*for(int x=0;x<12;x++)
for(int i=0;i<12;i++)
//dat[i] = read_data ();
dat[x]=input[i];*/

pinMode (DHpin, OUTPUT);

digitalWrite (DHpin, HIGH);

// send data once after releasing the bus, wait for the host to open the next Start signal

}

void loop () {


start_test ();

    count = 0;      // Reset the counter to zero
    temp = "";
    // convert the bit data to string form
for(int i=0;i<13;i++)
temp += input[i];
Serial.println(temp);
//Serial.println(temp);


data = "tag=" + temp;// data sent must be under this form //name1=value1&name2=value2.

httppost();

delay(200);

}

void httppost () {

esp.println("AT+CIPSTART=\"TCP\",\"" + server + "\",80");//start a TCP connection.

if( esp.find("OK")) {

Serial.println("TCP connection ready");

} delay(100);

String postRequest =

"POST " + uri + " HTTP/1.0\r\n" +

"Host: " + server + "\r\n" +

"Accept: *" + "/" + "*\r\n" +

"Content-Length: " + data.length() + "\r\n" +

"Content-Type: application/x-www-form-urlencoded\r\n" +

"\r\n" + data;

String sendCmd = "AT+CIPSEND=";//determine the number of caracters to be sent.

esp.print(sendCmd);

esp.println(postRequest.length() );

delay(500);

if(esp.find(">")) { Serial.println("Sending.."); esp.print(postRequest);

if( esp.find("SEND OK")) { Serial.println("Packet sent");

//while (esp.available()) {

//String tmpResp = esp.readString();

//Serial.println(tmpResp);

//}

// close the connection

esp.println("AT+CIPCLOSE");

}

}}

Cedric Don Coloma · Accepted Answer · 2019-01-29 13:53:15Z

0

You can follow this awesome tutorial if you want to connect your RFID RC522 module to PHP. Source Code and a step by step tutorial are provided. You only need NodeMcu and RC522 RFID module. https://devcraze.com/tutorials/connecting-rfid-scanner-to-php-using-nodemcu-wifi-module/

answered Jan 29, 2019 at 13:53

Cedric Don Coloma

1

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