deep sleep mode

code-snippets/client/deep_sleep/f_deep_sleep/examples/deep_sleep_timer_wake_up/deep_sleep_timer_wake_up.ino

+#include <f_deep_sleep.h>
+/*
+This code is under Public Domain License.
+Author: Pranav Cherukupalli <cherukupallip@gmail.com>
+*/
+
+/* Data saved on the RTC memory will not be deletet while the deep sleep mode */
+RTC_DATA_ATTR int bootCount = 0;
+/* First we configure the wake up source We set our ESP32 to wake up every 5 seconds */
+#define TIME_TO_SLEEP 5
+
+void setup(){
+  Serial.begin(115200);
+  Serial.println("******************After weak up Programm starts in setup**********************");
+  delay(1000); //Take some time to open up the Serial Monitor
+
+}
+
+
+void loop(){
+  ++bootCount;
+  Serial.println("Boot number: " + String(bootCount));
+  //Print the wakeup reason for ESP32
+  print_wakeup_reason();
+  Serial.println("Setup ESP32 to sleep for every " + String(TIME_TO_SLEEP) + " Seconds");
+  Serial.println("Going to sleep now");
+  Serial.println();
+  Serial.flush();
+  //going to sleep
+  deep_sleep(TIME_TO_SLEEP);
+}

code-snippets/client/deep_sleep/f_deep_sleep/f_deep_sleep.cpp

+#include "f_deep_sleep.h"
+
+void print_wakeup_reason(){
+  esp_sleep_wakeup_cause_t wakeup_reason;
+
+  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;
+    default : Serial.printf("Wakeup was not caused by deep sleep: %d\n",wakeup_reason); break;
+  }
+}
+
+
+void deep_sleep(int time_in_sec){//Increment boot number and print it every reboot
+  esp_sleep_enable_timer_wakeup(time_in_sec * 1000000);
+  esp_deep_sleep_start();
+}

code-snippets/client/deep_sleep/f_deep_sleep/f_deep_sleep.h

+#ifndef F_DEEP_SLEEP_H
+#define F_DEEP_SLEEP_H
+#include <Arduino.h>
+void deep_sleep(int time_to_sleep);
+void print_wakeup_reason();
+#endif