Light sleep wake-up via gpio on esp32

Question

I have a simple code for esp32 here. I can only use gpio pin number 35 on the board. So esp32 should go to light sleep and wake up on button press. When I run this program below, my esp32 goes into light sleep, but it doesn't wake up when the button is pressed. What's the problem? Any idea please? Thank you.

#include <esp_sleep.h>

void setup() {

  Serial.begin(115200);
  delay(2000);
  gpio_wakeup_enable(GPIO_NUM_35, GPIO_INTR_HIGH_LEVEL);
  esp_sleep_enable_gpio_wakeup();
  delay(2000); 
  Serial.println("Going to sleep now");
  delay(2000); 
  esp_light_sleep_start();
  delay(2000); 
  Serial.println("This will be NOT printed");

}

void loop() {
  delay(2000); 
  Serial.println("Hi after wake up via GPIO Button!");
  delay(2000); 
}

Answer 1

I've figured out by myself, what the trouble was: just change to rtc_io ext0 and set level on 0. Then it will work fine. Hope, it can be helpful for another users. Kind regards!