ExternalWakeUp.ino

/*
  Deep Sleep with External Wake Up
  =====================================
  This code displays how to use deep sleep with
  an external trigger as a wake up source and how
  to store data in RTC memory to use it over reboots

  This code is under Public Domain License.

  Hardware Connections
  ======================
  Push Button to GPIO 33 pulled down with a 10K Ohm
  resistor

  NOTE:
  ======
  Only RTC IO can be used as a source for external wake
  source. They are pins: 0,2,4,12-15,25-27,32-39.

  Author:
  Pranav Cherukupalli <cherukupallip@gmail.com>
*/
#include "driver/rtc_io.h"

#define BUTTON_PIN_BITMASK(GPIO) (1ULL << GPIO)  // 2 ^ GPIO_NUMBER in hex
#define USE_EXT0_WAKEUP 1  // 1 = EXT0 wakeup, 0 = EXT1 wakeup
#define WAKEUP_GPIO GPIO_NUM_33 // Only RTC IO are allowed - ESP32 Pin example
RTC_DATA_ATTR int bootCount = 0;

/*
  Method to print the reason by which ESP32
  has been awaken from sleep
*/
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 setup() {
  Serial.begin(115200);
  delay(1000);  //Take some time to open up the Serial Monitor

  //Increment boot number and print it every reboot
  ++bootCount;
  Serial.println("Boot number: " + String(bootCount));

  //Print the wakeup reason for ESP32
  print_wakeup_reason();

  /*
    First we configure the wake up source
    We set our ESP32 to wake up for an external trigger.
    There are two types for ESP32, ext0 and ext1 .
    ext0 uses RTC_IO to wakeup thus requires RTC peripherals
    to be on while ext1 uses RTC Controller so does not need
    peripherals to be powered on.
    Note that using internal pullups/pulldowns also requires
    RTC peripherals to be turned on.
  */
#if USE_EXT0_WAKEUP
  esp_sleep_enable_ext0_wakeup(WAKEUP_GPIO, 1);  //1 = High, 0 = Low
  // Configure pullup/downs via RTCIO to tie wakeup pins to inactive level during deepsleep.
  // EXT0 resides in the same power domain (RTC_PERIPH) as the RTC IO pullup/downs.
  // No need to keep that power domain explicitly, unlike EXT1.
  rtc_gpio_pullup_dis(WAKEUP_GPIO);
  rtc_gpio_pulldown_en(WAKEUP_GPIO);
  
#else // EXT1 WAKEUP
  //If you were to use ext1, you would use it like
  esp_sleep_enable_ext1_wakeup_io(BUTTON_PIN_BITMASK(WAKEUP_GPIO), ESP_EXT1_WAKEUP_ANY_HIGH);
  /*
    If there are no external pull-up/downs, tie wakeup pins to inactive level with internal pull-up/downs via RTC IO
         during deepsleep. However, RTC IO relies on the RTC_PERIPH power domain. Keeping this power domain on will
         increase some power comsumption. However, if we turn off the RTC_PERIPH domain or if certain chips lack the RTC_PERIPH
         domain, we will use the HOLD feature to maintain the pull-up and pull-down on the pins during sleep.
  */
  rtc_gpio_pulldown_en(WAKEUP_GPIO);  // GPIO33 is tie to GND in order to wake up in HIGH
  rtc_gpio_pullup_dis(WAKEUP_GPIO);   // Disable PULL_UP in order to allow it to wakeup on HIGH
#endif
  //Go to sleep now
  Serial.println("Going to sleep now");
  esp_deep_sleep_start();
  Serial.println("This will never be printed");
}

void loop() {
  //This is not going to be called
}