Timer Wake-Up

#include <esp_sleep.h>

#define TIME_TO_SLEEP  10  // Sleep time in seconds

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

    Serial.println("ESP32 going to deep sleep...");
    esp_sleep_enable_timer_wakeup(TIME_TO_SLEEP * 1000000);  // Convert seconds to microseconds

    esp_deep_sleep_start();
}

void loop() {
    // This won't run after deep sleep, as ESP32 restarts upon wake-up
}

1. The ESP32 executes the setup() function.
2. It prints a message, configures the wake-up timer, and enters deep sleep.
3. After the timer expires, the ESP32 wakes up and restarts from setup().

Since RTC memory is not used, the ESP32 enters Hibernation Mode, consuming only ~5µA.