Get data from website with ESP8266 using AT commands

Question

I'm trying to get data from a website by sending a HTTP GET request via AT commands for the ESP8266. Here is my current code:

#include <SoftwareSerial.h>

const byte rxPin = 2;
const byte txPin = 3;

SoftwareSerial ESP8266 (rxPin, txPin);

void setup() {
  Serial.begin(9600);   
  ESP8266.begin(9600);
  delay(2000);
}

void printResponse() {
  while (ESP8266.available()) {
    Serial.println(ESP8266.readStringUntil('\n')); 
  }
}

void loop() {

  ESP8266.println("AT+CIPMUX=1");
  delay(1000);
  printResponse();

  ESP8266.println("AT+CIPSTART=4,\"TCP\",\"192.168.1.19\",80");
  delay(1000);
  printResponse();

  String cmd = "GET /test.html HTTP/1.1";
  ESP8266.println("AT+CIPSEND=4," + String(cmd.length() + 4));
  delay(1000);

  ESP8266.println(cmd);
  delay(1000);
  ESP8266.println();
  delay(1000);
  printResponse();

  delay(5000);
}

Running this code I get the following response:

AT+CIPMUX=1

OK
AT+CIPSTART=4,"TCP","192.168.1.19",80
4,CONNECT

OK
AT+CIPSEND=4,27

OK
> 
Recv 27 bytes

SEND OK

+IPD,4,

It looks like it gets a response, but nothing is printed.

I tried doing the same thing by sending the AT commands manually using this code:

#include <SoftwareSerial.h>

const byte rxPin = 2;
const byte txPin = 3;
SoftwareSerial ESP8266 (rxPin, txPin);

void setup() {
  Serial.begin(9600);
  ESP8266.begin(9600);
}

void loop() {
  if (ESP8266.available()) {
    Serial.write(ESP8266.read());
  }
  if (Serial.available()) {
    ESP8266.write(Serial.read());
  }
}

With this approach I actually get a response:

AT+CIPMUX=1

OK
AT+CIPSTART=4,"TCP","192.168.1.19",80
4,CONNECT

OK
AT+CIPSEND=4,27

OK
> 
Recv 27 bytes

SEND OK

+IPD,4,275:HTTP/1.1 200 OK
Date: Thu, 22 Dec 2016 20:20:47 GMT
Server: Apache/2.4.23 (Win64) PHP/5.6.25
Last-Modified: Thu, 22 Dec 2016 19:37:22 GMT
ETag: "13-5444465f69339"
Accept-Ranges: bytes
Content-Length: 19
Connection: close
Content-Type: text/html

THIS IS MY WEBSITE!4,CLOSED

Does anyone know what is happening and how I can get this to work with my Arduino code?

Other ways to get data from a website are also welcome.

Answer 1

As pointed out in the first comment, my printResponse() function was not working correctly when waiting for a response from a website. I changed my code to the following, and now it seems to work every time.

#include <SoftwareSerial.h>

const byte rxPin = 2;
const byte txPin = 3;

SoftwareSerial ESP8266 (rxPin, txPin);

unsigned long lastTimeMillis = 0;

void setup() {
  Serial.begin(9600);   
  ESP8266.begin(9600);
  delay(2000);
}

void printResponse() {
  while (ESP8266.available()) {
    Serial.println(ESP8266.readStringUntil('\n')); 
  }
}

void loop() {

  if (millis() - lastTimeMillis > 30000) {
    lastTimeMillis = millis();

    ESP8266.println("AT+CIPMUX=1");
    delay(1000);
    printResponse();

    ESP8266.println("AT+CIPSTART=4,\"TCP\",\"192.168.1.19\",80");
    delay(1000);
    printResponse();

    String cmd = "GET /test.html HTTP/1.1";
    ESP8266.println("AT+CIPSEND=4," + String(cmd.length() + 4));
    delay(1000);

    ESP8266.println(cmd);
    delay(1000);
    ESP8266.println(""); 
  }

  if (ESP8266.available()) {
    Serial.write(ESP8266.read());
  }

}

Answer 2

Slightly modified code. With the addition of a more correct query

#include <SoftwareSerial.h>

const byte rxPin = 2;
const byte txPin = 3;

SoftwareSerial ESP8266 (rxPin, txPin);

unsigned long lastTimeMillis = 0;

void setup() {
  Serial.begin(9600);   
  ESP8266.begin(9600);
  delay(2000);
}

void printResponse() {
  while (ESP8266.available()) {
    Serial.println(ESP8266.readStringUntil('\n')); 
  }
}

void loop() {

  if (millis() - lastTimeMillis < 3000) {
    lastTimeMillis = millis();

    ESP8266.println("AT+CIPMUX=1");
    delay(1000);
    printResponse();

    ESP8266.println("AT+CIPSTART=4,\"TCP\",\"192.168.0.79\",80");
    delay(1000);
    printResponse();

    String cmd = "GET / HTTP/1.1\r\nHost: 192.168.0.79\r\nConnection: close\r\n\r\n";
    ESP8266.println("AT+CIPSEND=4," + String(cmd.length() + 4));
    delay(1000);

    ESP8266.println(cmd);
    delay(1000);
    ESP8266.println(""); 
  }

  if (ESP8266.available()) {
    Serial.write(ESP8266.read());
  }

}