const int buttonPin = 33;
const int ledPin = 17;
int buttonState = 0;
int lastMillis = 0;

void IRAM_ATTR function_ISR() {
 if(millis() - lastMillis > 100){ // Software debouncing buton
         Serial.println("ISR triggered");
         //ets_printf("ISR triggered\n");
         buttonState = !buttonState;
         digitalWrite(ledPin,buttonState);
 }
 lastMillis = millis();
}

void setup() {
 Serial.begin(115200);
 pinMode(buttonPin, INPUT_PULLUP);
 pinMode(ledPin,OUTPUT);
 attachInterrupt(buttonPin, function_ISR, CHANGE);
 digitalWrite(ledPin, buttonState);
}

void loop() {
 // Code ...
}