ESP8266 Conectado WI-FI com WPS/QSS (sem senha no código fonte)

 Para acabar com o problema de quando muda a senha do wi-fi ter que recompilar o código segue o código para uso do botão WPS/QSS.

Para conectar o ESP8266 pela primeira vez no wi-fi, basta pressionar primeiramente o WPS do roteador e depois o WPS  do ESP8266 ilustrado na foto abaixo onde o botão WPS é feito com um push buton ligando o pino D4 com o Ground.

Para reconectar quando muda a senha do wi-fi basta pressionar o WPS do roteador, não precisa pressionar o WPS do ESP8266.

/***************************************************************************
#include <ESP8266WiFi.h>
bool debug = false;
#define MAX_SRV_CLIENTS 1
WiFiServer server(23);  //  port 23 = telnet
WiFiClient serverClients[MAX_SRV_CLIENTS];
bool startWPSPBC() {
  Serial.println("WPS config start");
  bool wpsSuccess = WiFi.beginWPSConfig();
  if (wpsSuccess) {
    // Well this means not always success :-/ in case of a timeout we have an empty ssid
    String newSSID = WiFi.SSID();
    if (newSSID.length() > 0) {
      // WPSConfig has already connected in STA mode successfully to the new station.
      Serial.printf("WPS finished. Connected successfull to SSID '%s'\n", newSSID.c_str());
    } else {
      wpsSuccess = false;
    }
  }
  return wpsSuccess;
}

void setup() {
  Serial.begin(9600);        // adopt baud rate to your needs
  delay(1000);
  if (debug) {
    Serial.println("\n WPS with push button on GPIO2 input, LOW = active");
    Serial.printf("\nTry connecting to WiFi with SSID '%s'\n", WiFi.SSID().c_str());
  }

  WiFi.mode(WIFI_STA);
  WiFi.begin(WiFi.SSID().c_str(), WiFi.psk().c_str()); // reading data from EPROM,
  while (WiFi.status() == WL_DISCONNECTED) {          // last saved credentials
    delay(500);
    if (debug) Serial.print(".");
  }

  wl_status_t status = WiFi.status();
  if (status == WL_CONNECTED) {
    if (debug) Serial.printf("\nConnected successful to SSID '%s'\n", WiFi.SSID().c_str());
  } else {
    // WPS button I/O setup
    pinMode(0, OUTPUT);        // Use GPIO0
    digitalWrite(0, LOW);      // for hardware safe operation.
    pinMode(2, INPUT_PULLUP);  // Push Button for GPIO2 active LOW
    Serial.printf("\nCould not connect to WiFi. state='%d'\n", status);
    Serial.println("Please press WPS button on your router, until mode is indicated.");
    Serial.println("next press the ESP module WPS button, router WPS timeout = 2 minutes");

    while (digitalRead(2) == HIGH) // wait for WPS Button active
      yield(); // do nothing, allow background work (WiFi) in while loops
    Serial.println("WPS button pressed");

    if (!startWPSPBC()) {
      Serial.println("Failed to connect with WPS :-(");
    } else {
      WiFi.begin(WiFi.SSID().c_str(), WiFi.psk().c_str()); // reading data from EPROM,
      while (WiFi.status() == WL_DISCONNECTED) {          // last saved credentials
        delay(500);
        Serial.print("."); // show wait for connect to AP
      }
      pinMode(0, INPUT);   // GPIO0, LED OFF, show WPS & connect OK
    }
  }

  server.begin();  // telnet server
  server.setNoDelay(true);
  if (debug) {
    Serial.print("\nReady! Use 'telnet ");
    Serial.print(WiFi.localIP());
    Serial.println(" port 23' to connect");
  }
}


void loop() {
  uint8_t i;
  //check if there are any new clients
  if (server.hasClient()) {
    for (i = 0; i < MAX_SRV_CLIENTS; i++) {
      //find free/disconnected spot
      if (!serverClients[i] || !serverClients[i].connected()) {
        if (serverClients[i]) serverClients[i].stop();
        serverClients[i] = server.available();
        if (debug) {
          Serial.print("New client: ");
          Serial.println(i);
        }
        continue;
      }
    }
    //no free/disconnected spot so reject
    WiFiClient serverClient = server.available();
    serverClient.stop();
  }
  //check clients for data
  for (i = 0; i < MAX_SRV_CLIENTS; i++) {
    if (serverClients[i] && serverClients[i].connected()) {
      if (serverClients[i].available()) {
        //get data from the telnet client and push it to the UART
        while (serverClients[i].available()) Serial.write(serverClients[i].read());
      }
    }
  }
  //check UART for data
  if (Serial.available()) {
    size_t len = Serial.available();
    uint8_t sbuf[len];
    Serial.readBytes(sbuf, len);
    //push UART data to all connected telnet clients
    for (i = 0; i < MAX_SRV_CLIENTS; i++) {
      if (serverClients[i] && serverClients[i].connected()) {
        serverClients[i].write(sbuf, len);
        delay(1);  // for multitasking
      }
    }
  }
}