#define LED_PIN 14 // GPIO pin where the LED is connected on the M5Core2
hw_timer_t*timer=NULL;
int cont=0;

void IRAM_ATTR changeState() {
  digitalWrite(LED_PIN, !(digitalRead(LED_PIN)));
  cont++;
  if(cont==20) timerStop(timer);
}

void setup() {
 //M5.begin(); // Initialize the M5Core2 hardware (display, I2C, etc.)
 pinMode(LED_PIN, OUTPUT); // Configure the LED pin as an output
 timer = timerBegin(80000);
 timerAttachInterrupt(timer, &changeState);
 timerWrite (timer, 500000);
 timerAlarm(timer, 80000, true, 0); 
}

void loop() {
}