#define MODE 5
#define DEBOUNCE_TIME 200

void IRAM_ATTR modeISR();

volatile int mode = 0;
volatile bool modeChanged = false;
volatile unsigned long prev_press = millis();

//----------------------------------------------------------------------------------------------------------------------
void setup()
{
  Serial.begin(57600);
  pinMode(8, INPUT_PULLUP);
  pinMode(MODE, INPUT_PULLUP);
  attachInterrupt(digitalPinToInterrupt(MODE), modeISR, RISING);
}
//----------------------------------------------------------------------------------------------------------------------
void loop()
{
  if (digitalRead(8) == LOW)
    Serial.print('~');
  
  if (modeChanged) {
    modeChanged = false;
    Serial.print(mode);
  }

  delay(100);
}

void IRAM_ATTR modeISR()
{
  if (millis() - prev_press < DEBOUNCE_TIME)
    return;
  prev_press = millis();
  mode++;
  modeChanged = true;
}