SmartConfig ESP8266 save Wifi configuration on Pin0

smartconfig_save.ino

#include <ESP8266WiFi.h>
#include <WiFiUdp.h>

void setup() {
  int cnt = 0;  
  WiFi.mode(WIFI_STA);
  Serial.begin(9600);
  pinMode(0, INPUT_PULLUP);
  Serial.println("2 sec before clear SmartConfig");
  delay(2000);

  int isSmartConfig = digitalRead(0);
  if (isSmartConfig==0) {
    Serial.println("clear config");
    WiFi.disconnect();
  }

  // if wifi cannot connect start smartconfig
  while(WiFi.status() != WL_CONNECTED) {
    delay(500);
    Serial.print(".");
    if(cnt++ >= 15){
       WiFi.beginSmartConfig();
       while(1){
           delay(500);
           if(WiFi.smartConfigDone()){
             Serial.println("SmartConfig Success");
             break;
           }
       }
    }
  }

  Serial.println("");
  WiFi.printDiag(Serial);
  // Print the IP address
  Serial.println(WiFi.localIP());
  Serial.println(WiFi.macAddress());

}

void loop() { 
}