Implementation of deep sleep with wakeup button for the M5StickC

M5StickC_DeepSleep.ino

#include <esp_sleep.h>
#include <esp_wifi.h>
#include <esp_bt.h>
#include <esp_bt_main.h>
#include <driver/adc.h>
#include <M5StickC.h>

void setup() {
  M5.begin();
  Serial.begin(115200);
  while (Serial.available()) char c = Serial.read();
  delay(200);
  Serial.println("Deep Sleep Test.");
  Serial.println("Press Button A to go to sleep and come back.");
}

void loop() {
  M5.update();
  if (M5.BtnA.isPressed()) {
    Serial.println("Going to sleep");
    myDeepSleep((gpio_num_t)BUTTON_A_PIN);
    Serial.println("Hello!");
  }
}

void myDeepSleep(gpio_num_t PIN) {
  esp_sleep_enable_ext0_wakeup(PIN, LOW);
  esp_sleep_pd_config(ESP_PD_DOMAIN_RTC_PERIPH, ESP_PD_OPTION_AUTO);
  while (digitalRead(BUTTON_A_PIN) == LOW) delay(10);
  M5.Axp.SetSleep();
  esp_wifi_stop();
  /*
    On recommendation from https://twitter.com/ioPush_net
    to further reduce consumption
  */
  esp_bluedroid_disable();
  esp_bluedroid_deinit();
  esp_bt_controller_disable();
  esp_bt_controller_deinit();
  esp_bt_mem_release(ESP_BT_MODE_BTDM);
  adc_power_off();
  esp_deep_sleep_start();
}