#define LED 33
#define btn 13

//ESP-32 = IRAM_ATTR
//ESP-8266 = ICACHE_IRAM_ATTR
void IRAM_ATTR adaIntrupsi(){
  digitalWrite(LED, !digitalRead(LED));
}

void setup() {
  pinMode(LED, OUTPUT); digitalWrite(LED, HIGH);
  delay(200);
  pinMode(btn, INPUT_PULLUP);
  attachInterrupt(btn, adaIntrupsi, FALLING);
}
void loop(){

}