Standalone ESP8266/ESP-12: web control on-board LED

It's a example of Standalone ESP8266/ESP-12 web server, to control on-board LED.

Prepare:
- Install ESP8266 Board to Arduino IDE
- Program standalone ESP8266/ESP-12 WiFi module with Arduino IDE
- Simple Web Server example of standalone ESP8266/ESP-12 WiFi Module

This example modify from the last example Simple Web Server example of standalone ESP8266/ESP-12 WiFi Module, to control on-board LED. You need a Terminal program (ex. Arduino IDE's Serial Monitor) to display the ESP8266's IP.

ESP12-WebControlLed.ino

#include <ESP8266WiFi.h>
#include <WiFiClient.h>
#include <ESP8266WebServer.h>
#include <ESP8266mDNS.h>
 
const char* ssid = "testAP";
const char* password = "12345678";
MDNSResponder mdns;

ESP8266WebServer server(80);

const int led = 13;

void handleRoot() {
  server.send(200, "text/plain", 
    "hello from esp8266!) \n/on: to tuen LED ON \n/off: to tuen LED OFF \n");

}

void handleNotFound(){
  digitalWrite(led, 1);
  String message = "File Not Found\n\n";
  message += "URI: ";
  message += server.uri();
  message += "\nMethod: ";
  message += (server.method() == HTTP_GET)?"GET":"POST";
  message += "\nArguments: ";
  message += server.args();
  message += "\n";
  for (uint8_t i=0; i<server.args(); i++){
    message += " " + server.argName(i) + ": " + server.arg(i) + "\n";
  }
  server.send(404, "text/plain", message);
  digitalWrite(led, 0);
}
 
void setup(void){
  pinMode(led, OUTPUT);
  digitalWrite(led, 0);
  Serial.begin(115200);
  WiFi.begin(ssid, password);
  Serial.println("");

  // Wait for connection
  while (WiFi.status() != WL_CONNECTED) {
    delay(500);
    Serial.print(".");
  }
  Serial.println("");
  Serial.print("Connected to ");
  Serial.println(ssid);
  Serial.print("IP address: ");
  Serial.println(WiFi.localIP());
  
  if (mdns.begin("esp8266", WiFi.localIP())) {
    Serial.println("MDNS responder started");
  }
  
  server.on("/", handleRoot);

  server.on("/on", [](){
    digitalWrite(BUILTIN_LED, LOW);
    server.send(200, "text/plain", "LED ON");
  });
  
  server.on("/off", [](){
    digitalWrite(BUILTIN_LED, HIGH);
    server.send(200, "text/plain", "LED OFF");
  });

  server.onNotFound(handleNotFound);
  
  server.begin();
  Serial.println("HTTP server started");

  //delay a moment, 
  //for terminal to receive inf, such as IP address
  delay(1000);
  Serial.end();
  pinMode(BUILTIN_LED, OUTPUT);
}
 
void loop(void){
  server.handleClient();
} 

Android App to test:
- Android App to control Standalone ESP8266/ESP-12 on-board LED, using HttpClient, with Android example code.

- Android App to control Standalone ESP8266/ESP-12 on-board LED, using HttpURLConnection, with Android example code and APK for test without coding.

Simple Web Server example of standalone ESP8266/ESP-12 WiFi Module

Former posts show how to "Install ESP8266 Board to Arduino IDE" and "Program standalone ESP8266/ESP-12 WiFi module with Arduino IDE". ESP8266 Board Library come with a HelloServer example, it's easy to implement a simple web server.

Load ESP8266WebServer example of HelloServer, change ssid and password for your WiFi network, Save another file.

Next:
- Standalone ESP8266/ESP-12: web control on-board LED

Program standalone ESP8266/ESP-12 WiFi module with Arduino IDE

This post show how to program and run standalone ESP8266/ESP-12 WiFi module. To program ESP8266 board with Arduino, we have to "Install ESP8266 Board to Arduino IDE".

Connect USB-to-Serial adapter to ESP8266/ESP-12 board, FT232RL module is used in this example.

Minimal Hardware Setup for Bootloading only

ESPxx Hardware

PIN	Resistor	Serial Adapter
VCC		VCC (3.3V)
GND		GND
TX or GPIO2		RX
RX		TX
GPIO0		GND
Reset		RTS*
GPIO15	PullDown
CH_PD	PullUp

• Note
  • if no RTS is used a manual power toggle is needed

Minimal Hardware Setup for Running only

ESPxx Hardware

PIN	Resistor	Power supply
VCC		VCC (3.3V)
GND		GND
GPIO0	PullUp
GPIO15	PullDown
CH_PD	PullUp

reference: https://github.com/esp8266/Arduino/blob/master/doc/boards.md

Load Examples > esp8266 > Blink

To program ESP8266 board, press the button to connect GPIO0 to GND. Because there are no RTS in my FT232RL module, so I have to power OFF and ON to reset ESP8266 before programming.

Once programmed, power off the board, press the button to release GPIO0, then power on again to run in standalone.

---

Updated@2015-11-15:
My setup have no RTS, so I add a button to reset the ESP-12 manually.

---

List of Standalone ESP8266 board posts:
- Install ESP8266 Board to Arduino IDE
- Program standalone ESP8266/ESP-12 WiFi module with Arduino IDE (this post)
- Simple Web Server example of standalone ESP8266/ESP-12 WiFi Module
- Standalone ESP8266/ESP-12: web control on-board LED

Fit ESP-12 Breakout Board on breadboard

I have a ESP8266 ESP-12 WiFi Module (Full I/O) Breakout Board. But the board cover whole the width of breadboard, such that cannot insert breadboard wire. Alternatively, I have some pre-cut wires for breadboard, can be inserted under the breakout board to make it fit on breadboard.

I also add a breadboard power supply (3.3V selectable), a FTDI adapter and button for flashing firmware. And wires to lead out the GPIO16, 14, 12 and 13 for future use.

Here is the wires placement:

Arduino + ESP8266 - Web Server (II)

Last exercise "Arduino + ESP8266 - a simpe web server response with HTML" use a simple approach to find the "+IPD" in the income stream. But if fail to detect it, the buffer will not be updated, it will stop and need restart. It's another approach using readBytesUntil() to load the data to another buffer, and find "+IPD" programmatically using strncmp(). Such that if fail to detect "+IPD", it still can work for next connection.


In order to know the pattern of "+IPD" and the connection id in the incoming stream, I make a test program to show it in Serial Monitor, refer to the bottom of this post.

Due8266Web.ino

/*
Arduino Due - ESP 8266 WiFi Module
Serial (Tx/Rx) communicate to PC via USB
Serial3 (Tx3/Rx3) connect to ESP8266
Tx3 - ESP8266 Rx
Rx3 - ESP8266 Tx
ESP8266 CH_PD Connect to ESP8266 VCC
*/
#define ASCII_0 48
#define ESP8266 Serial3
String SSID = "TestAP";
String PASSWORD = "12345678";

int LED = 13;

boolean FAIL_8266 = false;

String strHTML = "<!doctype html>\
<html>\
<head>\
<title>arduino-er</title>\
</head>\
<body>\
<H1>arduino-er.blogspot.com</H1>\
</body>\
</html>";

#define BUFFER_SIZE 128
char buffer[BUFFER_SIZE];

void setup() {
  pinMode(LED, OUTPUT);
  
  digitalWrite(LED, LOW);
  delay(300);
  digitalWrite(LED, HIGH);
  delay(200);
  digitalWrite(LED, LOW);
  delay(300);
  digitalWrite(LED, HIGH);
  delay(200);
  digitalWrite(LED, LOW);
  delay(300);
  digitalWrite(LED, HIGH);
  delay(200);
  digitalWrite(LED, LOW);

  do{
    Serial.begin(9600);
    ESP8266.begin(9600);
  
    //Wait Serial Monitor to start
    while(!Serial);
    Serial.println("--- Start ---");

    ESP8266.println("AT+RST");
    delay(1000);
    if(ESP8266.find("ready"))
    {
      Serial.println("Module is ready");
      ESP8266.println("AT+CWMODE=1");
      delay(2000);
      
      //Quit existing AP, for demo
      Serial.println("Quit AP");
      ESP8266.println("AT+CWQAP");
      delay(1000);
      
      clearESP8266SerialBuffer();
      if(cwJoinAP())
      {
        Serial.println("CWJAP Success");
        FAIL_8266 = false;
        
        delay(3000);
        clearESP8266SerialBuffer();
        //Get and display my IP
        sendESP8266Cmdln("AT+CIFSR", 1000);  
        //Set multi connections
        sendESP8266Cmdln("AT+CIPMUX=1", 1000);
        //Setup web server on port 80
        sendESP8266Cmdln("AT+CIPSERVER=1,80",1000);
        
        Serial.println("Server setup finish");
      }else{
        Serial.println("CWJAP Fail");
        delay(500);
        FAIL_8266 = true;
      }
    }else{
      Serial.println("Module have no response.");
      delay(500);
      FAIL_8266 = true;
    }
  }while(FAIL_8266);
  
  digitalWrite(LED, HIGH);
}

void loop(){
  int connectionId;
  
  if(ESP8266.readBytesUntil('\n', buffer, BUFFER_SIZE)>0)
  {
    Serial.println("Something received");
    Serial.println(buffer);
    if(strncmp(buffer, "+IPD,", 5)==0){
      Serial.println("+IPD, found");
      sscanf(buffer+5, "%d", &connectionId);
      Serial.println("connectionId: " + String(connectionId));
      delay(1000);
      clearESP8266SerialBuffer();
      
      sendHTTPResponse(connectionId, strHTML);
      
      //Close TCP/UDP
      String cmdCIPCLOSE = "AT+CIPCLOSE="; 
      cmdCIPCLOSE += connectionId;
      sendESP8266Cmdln(cmdCIPCLOSE, 1000);
    }
  }
}

void sendHTTPResponse(int id, String content)
{
  String response;
  response = "HTTP/1.1 200 OK\r\n";
  response += "Content-Type: text/html; charset=UTF-8\r\n"; 
  response += "Content-Length: ";
  response += content.length();
  response += "\r\n";
  response +="Connection: close\r\n\r\n";
  response += content;

  String cmd = "AT+CIPSEND=";
  cmd += id;
  cmd += ",";
  cmd += response.length();
  
  Serial.println("--- AT+CIPSEND ---");
  sendESP8266Cmdln(cmd, 1000);
  
  Serial.println("--- data ---");
  sendESP8266Data(response, 1000);
}

boolean waitOKfromESP8266(int timeout)
{
  do{
    Serial.println("wait OK...");
    delay(1000);
    if(ESP8266.find("OK"))
    {
      return true;
    }

  }while((timeout--)>0);
  return false;
}

boolean cwJoinAP()
{
  String cmd="AT+CWJAP=\"" + SSID + "\",\"" + PASSWORD + "\"";
  ESP8266.println(cmd);
  return waitOKfromESP8266(10);
}

//Send command to ESP8266, assume OK, no error check
//wait some time and display respond
void sendESP8266Cmdln(String cmd, int waitTime)
{
  ESP8266.println(cmd);
  delay(waitTime);
  clearESP8266SerialBuffer();
}

//Basically same as sendESP8266Cmdln()
//But call ESP8266.print() instead of call ESP8266.println()
void sendESP8266Data(String data, int waitTime)
{
  ESP8266.print(data);
  delay(waitTime);
  clearESP8266SerialBuffer();
}

//Clear and display Serial Buffer for ESP8266
void clearESP8266SerialBuffer()
{
  Serial.println("= clearESP8266SerialBuffer() =");
  while (ESP8266.available() > 0) {
    char a = ESP8266.read();
    Serial.write(a);
  }
  Serial.println("==============================");
}

---

NOTICE:
In my test, sometimes the ESP8266 ESP-12 reset and show the vendor website. It's caused by the pre-load old firmware, to fix it, flash ESP8266 with new firmware. Refer to my next exercise with the updated firmware 00200.9.5(b1).

---

To know the "+IPD" and the connection id, I prepare this simple program to show the incoming data on Serial Monitor, without response back to the client.

testDue8266Web.ino

/*
Arduino Due - ESP 8266 WiFi Module
Serial (Tx/Rx) communicate to PC via USB
Serial3 (Tx3/Rx3) connect to ESP8266
Tx3 - ESP8266 Rx
Rx3 - ESP8266 Tx
ESP8266 CH_PD Connect to ESP8266 VCC
*/
#define ASCII_0 48
#define ESP8266 Serial3
//String SSID = "TestAP";
//String PASSWORD = "12345678";

int LED = 13;

boolean FAIL_8266 = false;

String strHTML = "<!doctype html>\
<html>\
<head>\
<title>arduino-er</title>\
</head>\
<body>\
<H1>arduino-er.blogspot.com</H1>\
</body>\
</html>";

void setup() {
  pinMode(LED, OUTPUT);
  
  digitalWrite(LED, LOW);
  delay(300);
  digitalWrite(LED, HIGH);
  delay(200);
  digitalWrite(LED, LOW);
  delay(300);
  digitalWrite(LED, HIGH);
  delay(200);
  digitalWrite(LED, LOW);
  delay(300);
  digitalWrite(LED, HIGH);
  delay(200);
  digitalWrite(LED, LOW);

  do{
    Serial.begin(9600);
    ESP8266.begin(9600);
  
    //Wait Serial Monitor to start
    while(!Serial);
    Serial.println("--- Start ---");

    ESP8266.println("AT+RST");
    delay(1000);
    if(ESP8266.find("ready"))
    {
      Serial.println("Module is ready");
      ESP8266.println("AT+CWMODE=2");
      delay(1000);
      
      clearESP8266SerialBuffer();
      sendESP8266Cmdln("AT+CIFSR", 1000);  
      //Set multi connections
      sendESP8266Cmdln("AT+CIPMUX=1", 1000);
      //Setup web server on port 80
      sendESP8266Cmdln("AT+CIPSERVER=1,80",1000);
      Serial.println("Server setup finish");
    }else{
      Serial.println("Module have no response.");
      delay(500);
      FAIL_8266 = true;
    }
  }while(FAIL_8266);
  
  digitalWrite(LED, HIGH);
}

void loop(){
  while (ESP8266.available() > 0) {
    char a = ESP8266.read();
    Serial.write(a);
  }
}

boolean waitOKfromESP8266(int timeout)
{
  do{
    Serial.println("wait OK...");
    delay(1000);
    if(ESP8266.find("OK"))
    {
      return true;
    }

  }while((timeout--)>0);
  return false;
}

//Send command to ESP8266, assume OK, no error check
//wait some time and display respond
void sendESP8266Cmdln(String cmd, int waitTime)
{
  ESP8266.println(cmd);
  delay(waitTime);
  clearESP8266SerialBuffer();
}

//Basically same as sendESP8266Cmdln()
//But call ESP8266.print() instead of call ESP8266.println()
void sendESP8266Data(String data, int waitTime)
{
  ESP8266.print(data);
  delay(waitTime);
  clearESP8266SerialBuffer();
}

//Clear and display Serial Buffer for ESP8266
void clearESP8266SerialBuffer()
{
  Serial.println("= clearESP8266SerialBuffer() =");
  while (ESP8266.available() > 0) {
    char a = ESP8266.read();
    Serial.write(a);
  }
  Serial.println("==============================");
}

Arduino + ESP8266 - a simpe web server response with HTML

Implement a web server with Arduino Due + ESP8266 ESP-12, response HTML page.

Connection:

ESP-12 VCC connect to separated power of 3.3V

Due GND - ESP-12 GND

Due TX3 - ESP-12 RX

Due RX3 - ESP-12 TX

ESP-12 CH_PD connect to ESP-12 VCC

Due connect with PC USB, such that we can monitor the status of ESP-12.

Start Serial Monitor, at 9600 baud, to reset and start run the program.

Due8266Web.ino

/*
Arduino Due - ESP 8266 WiFi Module
Serial (Tx/Rx) communicate to PC via USB
Serial3 (Tx3/Rx3) connect to ESP8266
Tx3 - ESP8266 Rx
Rx3 - ESP8266 Tx
ESP8266 CH_PD Connect to ESP8266 VCC
*/
#define ASCII_0 48
#define ESP8266 Serial3
String SSID = "TestAP";
String PASSWORD = "12345678";

int LED = 13;

boolean FAIL_8266 = false;

String strHTML = "<!doctype html>\
<html>\
<head>\
<title>arduino-er</title>\
</head>\
<body>\
<H1>arduino-er.blogspot.com</H1>\
</body>\
</html>";

void setup() {
  pinMode(LED, OUTPUT);
  
  digitalWrite(LED, LOW);
  delay(300);
  digitalWrite(LED, HIGH);
  delay(200);
  digitalWrite(LED, LOW);
  delay(300);
  digitalWrite(LED, HIGH);
  delay(200);
  digitalWrite(LED, LOW);
  delay(300);
  digitalWrite(LED, HIGH);
  delay(200);
  digitalWrite(LED, LOW);

  do{
    Serial.begin(9600);
    ESP8266.begin(9600);
  
    //Wait Serial Monitor to start
    while(!Serial);
    Serial.println("--- Start ---");

    ESP8266.println("AT+RST");
    delay(1000);
    if(ESP8266.find("ready"))
    {
      Serial.println("Module is ready");
      ESP8266.println("AT+CWMODE=1");
      delay(2000);
      
      //Quit existing AP, for demo
      Serial.println("Quit AP");
      ESP8266.println("AT+CWQAP");
      delay(1000);
      
      clearESP8266SerialBuffer();
      if(cwJoinAP())
      {
        Serial.println("CWJAP Success");
        FAIL_8266 = false;
        
        delay(3000);
        clearESP8266SerialBuffer();
        //Get and display my IP
        sendESP8266Cmdln("AT+CIFSR", 1000);  
        //Set multi connections
        sendESP8266Cmdln("AT+CIPMUX=1", 1000);
        //Setup web server on port 80
        sendESP8266Cmdln("AT+CIPSERVER=1,80",1000);
        
        Serial.println("Server setup finish");
      }else{
        Serial.println("CWJAP Fail");
        delay(500);
        FAIL_8266 = true;
      }
    }else{
      Serial.println("Module have no response.");
      delay(500);
      FAIL_8266 = true;
    }
  }while(FAIL_8266);
  
  digitalWrite(LED, HIGH);
}

void loop(){
  if(ESP8266.available())
  {
    Serial.println("Something received");
    delay(1000);
    if(ESP8266.find("+IPD,"))
    {
      String action;
      
      Serial.println("+IPD, found");
      int connectionId = ESP8266.read()-ASCII_0;
      Serial.println("connectionId: " + String(connectionId));
      
      sendHTTPResponse(connectionId, strHTML);
      
      //Close TCP/UDP
      String cmdCIPCLOSE = "AT+CIPCLOSE="; 
      cmdCIPCLOSE += connectionId;
      sendESP8266Cmdln(cmdCIPCLOSE, 1000);
    }
  }
}

void sendHTTPResponse(int id, String content)
{
  String response;
  response = "HTTP/1.1 200 OK\r\n";
  response += "Content-Type: text/html; charset=UTF-8\r\n"; 
  response += "Content-Length: ";
  response += content.length();
  response += "\r\n";
  response +="Connection: close\r\n\r\n";
  response += content;

  String cmd = "AT+CIPSEND=";
  cmd += id;
  cmd += ",";
  cmd += response.length();
  
  Serial.println("--- AT+CIPSEND ---");
  sendESP8266Cmdln(cmd, 1000);
  
  Serial.println("--- data ---");
  sendESP8266Data(response, 1000);
}

boolean waitOKfromESP8266(int timeout)
{
  do{
    Serial.println("wait OK...");
    delay(1000);
    if(ESP8266.find("OK"))
    {
      return true;
    }

  }while((timeout--)>0);
  return false;
}

boolean cwJoinAP()
{
  String cmd="AT+CWJAP=\"" + SSID + "\",\"" + PASSWORD + "\"";
  ESP8266.println(cmd);
  return waitOKfromESP8266(10);
}

//Send command to ESP8266, assume OK, no error check
//wait some time and display respond
void sendESP8266Cmdln(String cmd, int waitTime)
{
  ESP8266.println(cmd);
  delay(waitTime);
  clearESP8266SerialBuffer();
}

//Basically same as sendESP8266Cmdln()
//But call ESP8266.print() instead of call ESP8266.println()
void sendESP8266Data(String data, int waitTime)
{
  ESP8266.print(data);
  delay(waitTime);
  clearESP8266SerialBuffer();
}

//Clear and display Serial Buffer for ESP8266
void clearESP8266SerialBuffer()
{
  Serial.println("= clearESP8266SerialBuffer() =");
  while (ESP8266.available() > 0) {
    char a = ESP8266.read();
    Serial.write(a);
  }
  Serial.println("==============================");
}

Remark:
As shown in the video, it's sometimes unstable! Read the improved version in next post "Arduino + ESP8266 - Web Server (II)".

Arduino Due + ESP8266: Web Control LED

This example show how to implement a simple web server on Arduino Due with ESP8266 ESP-12 WiFi Module. User visit it with GET method to turn ON/OFF the on-board LED of Arduino Due.

to turn ON LED:
http://ipaddress?led=1
to turn OFF LED:
http://ipaddress?led=0

This demo run with ESP-12, suppose it work on any ESP8266 module.


In fact, it's not too stable! Sometime will lost if cannot detect "+IPD".

Connection:
ESP-12 VCC connect to separated power of 3.3V
Due GND - ESP-12 GND
Due TX3 - ESP-12 RX
Due RX3 - ESP-12 TX
ESP-12 CH_PD connect to ESP-12 VCC

Due connect with PC USB, such that we can monitor the status of ESP-12.

Start Serial Monitor, at 9600 baud, to reset and start run the program.

Due8266WebControlLed.ino

/*
Arduino Due - ESP 8266 WiFi Module
Serial (Tx/Rx) communicate to PC via USB
Serial3 (Tx3/Rx3) connect to ESP8266
Tx3 - ESP8266 Rx
Rx3 - ESP8266 Tx
ESP8266 CH_PD Connect to ESP8266 VCC
*/

#define ESP8266 Serial3
String SSID = "TestAP";
String PASSWORD = "12345678";

int LED = 13;

boolean FAIL_8266 = false;

void setup() {
  pinMode(LED, OUTPUT);
  
  digitalWrite(LED, LOW);
  delay(300);
  digitalWrite(LED, HIGH);
  delay(200);
  digitalWrite(LED, LOW);
  delay(300);
  digitalWrite(LED, HIGH);
  delay(200);
  digitalWrite(LED, LOW);
  delay(300);
  digitalWrite(LED, HIGH);
  delay(200);
  digitalWrite(LED, LOW);

  do{
    Serial.begin(9600);
    ESP8266.begin(9600);
  
    //Wait Serial Monitor to start
    while(!Serial);
    Serial.println("--- Start ---");

    ESP8266.println("AT+RST");
    delay(1000);
    if(ESP8266.find("ready"))
    {
      Serial.println("Module is ready");
      ESP8266.println("AT+CWMODE=1");
      delay(2000);
      
      //Quit existing AP, for demo
      Serial.println("Quit AP");
      ESP8266.println("AT+CWQAP");
      delay(1000);
      
      clearESP8266SerialBuffer();
      if(cwJoinAP())
      {
        Serial.println("CWJAP Success");
        FAIL_8266 = false;
        
        delay(3000);
        clearESP8266SerialBuffer();
        //Get and display my IP
        sendESP8266Cmdln("AT+CIFSR", 1000);  
        //Set multi connections
        sendESP8266Cmdln("AT+CIPMUX=1", 1000);
        //Setup web server on port 80
        sendESP8266Cmdln("AT+CIPSERVER=1,80",1000);
        
        Serial.println("Server setup finish");
      }else{
        Serial.println("CWJAP Fail");
        delay(500);
        FAIL_8266 = true;
      }
    }else{
      Serial.println("Module have no response.");
      delay(500);
      FAIL_8266 = true;
    }
  }while(FAIL_8266);
  
  digitalWrite(LED, HIGH);
}

void loop(){
  if(ESP8266.available()) 
  {
    Serial.println("Something received");
    delay(1000);
    if(ESP8266.find("+IPD,"))
    {
      String action;
      
      Serial.println("+IPD, found");
      int connectionId = ESP8266.read()-48;
      Serial.println("connectionId: " + String(connectionId));
      
      ESP8266.find("led=");
      char s = ESP8266.read();
      if(s=='0'){
        action = "led=0";
        digitalWrite(LED, LOW);
      }else if(s=='1'){
        action = "led=1";
        digitalWrite(LED, HIGH);
      }else{
        action = "led=?";
      }
      
      Serial.println(action);
      sendHTTPResponse(connectionId, action);
      
      //Close TCP/UDP
      String cmdCIPCLOSE = "AT+CIPCLOSE="; 
      cmdCIPCLOSE += connectionId;
      sendESP8266Cmdln(cmdCIPCLOSE, 1000);
    }
  }
}

void sendHTTPResponse(int id, String content)
{
  String response;
  response = "HTTP/1.1 200 OK\r\n";
  response += "Content-Type: text/html; charset=UTF-8\r\n"; 
  response += "Content-Length: ";
  response += content.length();
  response += "\r\n";
  response +="Connection: close\r\n\r\n";
  response += content;

  String cmd = "AT+CIPSEND=";
  cmd += id;
  cmd += ",";
  cmd += response.length();
  
  Serial.println("--- AT+CIPSEND ---");
  sendESP8266Cmdln(cmd, 1000);
  
  Serial.println("--- data ---");
  sendESP8266Data(response, 1000);
}

boolean waitOKfromESP8266(int timeout)
{
  do{
    Serial.println("wait OK...");
    delay(1000);
    if(ESP8266.find("OK"))
    {
      return true;
    }

  }while((timeout--)>0);
  return false;
}

boolean cwJoinAP()
{
  String cmd="AT+CWJAP=\"" + SSID + "\",\"" + PASSWORD + "\"";
  ESP8266.println(cmd);
  return waitOKfromESP8266(10);
}

//Send command to ESP8266, assume OK, no error check
//wait some time and display respond
void sendESP8266Cmdln(String cmd, int waitTime)
{
  ESP8266.println(cmd);
  delay(waitTime);
  clearESP8266SerialBuffer();
}

//Basically same as sendESP8266Cmdln()
//But call ESP8266.print() instead of call ESP8266.println()
void sendESP8266Data(String data, int waitTime)
{
  ESP8266.print(data);
  delay(waitTime);
  clearESP8266SerialBuffer();
}

//Clear and display Serial Buffer for ESP8266
void clearESP8266SerialBuffer()
{
  Serial.println("= clearESP8266SerialBuffer() =");
  while (ESP8266.available() > 0) {
    char a = ESP8266.read();
    Serial.write(a);
  }
  Serial.println("==============================");
}

Low cost ESP-12 (ESP8266 WiFi module)

It's ESP-12 (ESP8266 WiFi module) on breakout board, with all I/O pin accessible. Bought from China TaoBao (淘寶) market, cost RMB ¥15.00/pc :)

(have to solder the ESP-12 on breakout board by myself)

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Test with example of "Arduino Due + ESP8266 - to Join AP".

My first exercise of using ESP-12:
- Arduino Due + ESP8266: Web Control LED