void setup() {
  // put your setup code here, to run once:
  pinMode(LED_BUILTIN, OUTPUT);
  Serial.begin(9600);
}

void loop() {
  // put your main code here, to run repeatedly:
  digitalWrite(LED_BUILTIN, LOW);
  Serial.print("LED ON \n");
  delay(1000);
  digitalWrite(LED_BUILTIN, HIGH);
  Serial.print("LED OFF \n");
  delay(1000);
}

#define WAKEUP_PIN D0 // LP_GPIO1

RTC_DATA_ATTR int bootCount = 0;

void print_wakeup_reason(){
  esp_sleep_wakeup_cause_t wakeup_reason = esp_sleep_get_wakeup_cause();

  switch(wakeup_reason)
  {
    case ESP_SLEEP_WAKEUP_EXT0 : Serial.println("Wakeup caused by external signal using RTC_IO"); break;
    case ESP_SLEEP_WAKEUP_EXT1 : Serial.println("Wakeup caused by external signal using RTC_CNTL"); break;
    case ESP_SLEEP_WAKEUP_TIMER : Serial.println("Wakeup caused by timer"); break;
    case ESP_SLEEP_WAKEUP_TOUCHPAD : Serial.println("Wakeup caused by touchpad"); break;
    case ESP_SLEEP_WAKEUP_ULP : Serial.println("Wakeup caused by ULP program"); break;
    case ESP_SLEEP_WAKEUP_GPIO : Serial.println("Wakeup caused by GPIO"); break;
    default : Serial.printf("Wakeup was not caused by deep sleep: %d\n",wakeup_reason); break;
  }
}

void setup(){
  Serial.begin(115200);
  delay(1000);

  ++bootCount;
  Serial.println("Boot number: " + String(bootCount));
  print_wakeup_reason();

  pinMode(WAKEUP_PIN, INPUT_PULLUP);
  pinMode(LED_BUILTIN, OUTPUT);

  uint64_t mask = 1ULL << WAKEUP_PIN;
  esp_deep_sleep_enable_gpio_wakeup(mask, ESP_GPIO_WAKEUP_GPIO_HIGH);

  digitalWrite(LED_BUILTIN, LOW);
  delay(100);
  digitalWrite(LED_BUILTIN, HIGH);

  delay(2000);  //Delay time depends on the serial port / Give the PC time to stabilize
  Serial.println("Going to sleep now");
  esp_deep_sleep_start();
}

void loop(){}

#include <Arduino.h>

void setup() {
  Serial.begin(115200);
  pinMode(BAT_VOLT_PIN, INPUT);         // Configure A0 as ADC input
  pinMode(BAT_VOLT_PIN_EN , OUTPUT);
  digitalWrite(BAT_VOLT_PIN_EN , HIGH);
}

void loop() {
  uint32_t Vbatt = 0;
  for(int i = 0; i < 16; i++) {
    Vbatt += analogReadMilliVolts(BAT_VOLT_PIN ); // Read and accumulate ADC voltage
  }
  float Vbattf = 2 * Vbatt / 16 / 1000.0;     // Adjust for 1:2 divider and convert to volts
  Serial.println(Vbattf, 3);                  // Output voltage to 3 decimal places
  delay(1000);                                // Wait for 1 second
}