esp32-core/libraries/ESP32/examples/DeepSleep/TouchWakeUp/TouchWakeUp.ino

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

ESP32 can have multiple touch pads enabled as wakeup source
ESP32-S2 and ESP32-S3 supports only 1 touch pad as wakeup source enabled

This code is under Public Domain License.

Author:
Pranav Cherukupalli <cherukupallip@gmail.com>
*/

#if CONFIG_IDF_TARGET_ESP32
#define THRESHOLD 40 /* Greater the value, more the sensitivity */
#elif (CONFIG_IDF_TARGET_ESP32S2 || CONFIG_IDF_TARGET_ESP32S3)
#define THRESHOLD 5000 /* Lower the value, more the sensitivity */
#else                  // ESP32-P4 + default for other chips (to be adjusted) */
#define THRESHOLD 500  /* Lower the value, more the sensitivity */
#endif

RTC_DATA_ATTR int bootCount = 0;
touch_pad_t touchPin;
/*
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;
  }
}

/*
Method to print the touchpad by which ESP32
has been awaken from sleep
*/
void print_wakeup_touchpad() {
  touchPin = (touch_pad_t)esp_sleep_get_touchpad_wakeup_status();

#if CONFIG_IDF_TARGET_ESP32
  switch (touchPin) {
    case 0:  Serial.println("Touch detected on GPIO 4"); break;
    case 1:  Serial.println("Touch detected on GPIO 0"); break;
    case 2:  Serial.println("Touch detected on GPIO 2"); break;
    case 3:  Serial.println("Touch detected on GPIO 15"); break;
    case 4:  Serial.println("Touch detected on GPIO 13"); break;
    case 5:  Serial.println("Touch detected on GPIO 12"); break;
    case 6:  Serial.println("Touch detected on GPIO 14"); break;
    case 7:  Serial.println("Touch detected on GPIO 27"); break;
    case 8:  Serial.println("Touch detected on GPIO 33"); break;
    case 9:  Serial.println("Touch detected on GPIO 32"); break;
    default: Serial.println("Wakeup not by touchpad"); break;
  }
#else
  if (touchPin < TOUCH_PAD_MAX) {
    Serial.printf("Touch detected on GPIO %d\n", touchPin);
  } else {
    Serial.println("Wakeup not by touchpad");
  }
#endif
}

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 and touchpad too
  print_wakeup_reason();
  print_wakeup_touchpad();

#if CONFIG_IDF_TARGET_ESP32
  //Setup sleep wakeup on Touch Pad 3 + 7 (GPIO15 + GPIO 27)
  touchSleepWakeUpEnable(T3, THRESHOLD);
  touchSleepWakeUpEnable(T7, THRESHOLD);

#else  //ESP32-S2 + ESP32-S3 + ESP32-P4
  //Setup sleep wakeup on Touch Pad 3 (GPIO3)
  touchSleepWakeUpEnable(T3, THRESHOLD);

#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 will never be reached
}