#include <EEPROM.h>
bool ledState = 0;
bool lastBtn, btnState;
long lastTime = 0;
void setup(){
  Serial.begin(9600);
  EEPROM.begin(1);
  pinMode(2,OUTPUT); // led
  pinMode(23,INPUT_PULLUP); // button
}
void loop(){
  int readBtn = digitalRead(23);
  if(readBtn != lastBtn)
  {
    lastTime = millis();
  }
  if(millis() - lastTime > 200)
  {
    if(readBtn != btnState)
    {
      btnState = !btnState;
      if(btnState == 0)
      {
        ledState =! ledState;
      }
    }
  }
  lastBtn = readBtn;
  if(digitalRead(2) != ledState)
  {
    digitalWrite(2,ledState);
    EEPROM.write(0,ledState);
    EEPROM.commit();
  }
}