text: // Copyright 2015-2016 Espressif Systems (Shanghai) PTE LTD
  //
  // Licensed under the Apache License, Version 2.0 (the "License");
  // you may not use this file except in compliance with the License.
  // You may obtain a copy of the License at
  
  //     http://www.apache.org/licenses/LICENSE-2.0
  //
  // Unless required by applicable law or agreed to in writing, software
  // distributed under the License is distributed on an "AS IS" BASIS,
  // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  // See the License for the specific language governing permissions and
  // limitations under the License.
  
  #include <stdio.h>
  #include <stdlib.h>
  #include <unistd.h>
  #include <string.h>
  #include "freertos/FreeRTOS.h"
  #include "freertos/task.h"
  #include "nvs.h"
  #include "nvs_flash.h"
  #include "esp_system.h"
  #include "esp_log.h"
  
  #include "esp_bt.h"
  #include "bt_app_core.h"
  #include "bt_app_av.h"
  #include "esp_bt_main.h"
  #include "esp_bt_device.h"
  #include "esp_gap_bt_api.h"
  #include "esp_a2dp_api.h"
  #include "esp_avrc_api.h"
  #include "driver/i2s.h"
  
  /* event for handler "bt_av_hdl_stack_up */
  enum {
      BT_APP_EVT_STACK_UP = 0,
  };
  
  /* handler for bluetooth stack enabled events */
  static void bt_av_hdl_stack_evt(uint16_t event, void *p_param);
  
  
  void app_main()
  {
      /* Initialize NVS — it is used to store PHY calibration data */
      esp_err_t err = nvs_flash_init();
      if (err == ESP_ERR_NVS_NO_FREE_PAGES || err == ESP_ERR_NVS_NEW_VERSION_FOUND) {
          ESP_ERROR_CHECK(nvs_flash_erase());
          err = nvs_flash_init();
      }
      ESP_ERROR_CHECK(err);
  
      i2s_config_t i2s_config = {
  #ifdef CONFIG_A2DP_SINK_OUTPUT_INTERNAL_DAC
          .mode = I2S_MODE_MASTER | I2S_MODE_TX | I2S_MODE_DAC_BUILT_IN,
  #else
          .mode = I2S_MODE_MASTER | I2S_MODE_TX,                                  // Only TX
  #endif
          .sample_rate = 44100,
          .bits_per_sample = 16,
          .channel_format = I2S_CHANNEL_FMT_RIGHT_LEFT,                           //2-channels
          .communication_format = I2S_COMM_FORMAT_I2S_MSB,
          .dma_buf_count = 6,
          .dma_buf_len = 60,                                                      //
          .intr_alloc_flags = ESP_INTR_FLAG_LEVEL1                                //Interrupt level 1
      };
  
  
      i2s_driver_install(0, &i2s_config, 0, NULL);
  #ifdef CONFIG_A2DP_SINK_OUTPUT_INTERNAL_DAC
      i2s_set_dac_mode(I2S_DAC_CHANNEL_BOTH_EN);
      i2s_set_pin(0, NULL);
  #else
      i2s_pin_config_t pin_config = {
          .bck_io_num = CONFIG_I2S_BCK_PIN,
          .ws_io_num = CONFIG_I2S_LRCK_PIN,
          .data_out_num = CONFIG_I2S_DATA_PIN,
          .data_in_num = -1                                                       //Not used
      };
  
      i2s_set_pin(0, &pin_config);
  #endif
  
  
      ESP_ERROR_CHECK(esp_bt_controller_mem_release(ESP_BT_MODE_BLE));
  
      esp_bt_controller_config_t bt_cfg = BT_CONTROLLER_INIT_CONFIG_DEFAULT();
      if ((err = esp_bt_controller_init(&bt_cfg)) != ESP_OK) {
          ESP_LOGE(BT_AV_TAG, "%s initialize controller failed: %s\n", __func__, esp_err_to_name(err));
          return;
      }
  
      if ((err = esp_bt_controller_enable(ESP_BT_MODE_CLASSIC_BT)) != ESP_OK) {
          ESP_LOGE(BT_AV_TAG, "%s enable controller failed: %s\n", __func__, esp_err_to_name(err));
          return;
      }
  
      if ((err = esp_bluedroid_init()) != ESP_OK) {
          ESP_LOGE(BT_AV_TAG, "%s initialize bluedroid failed: %s\n", __func__, esp_err_to_name(err));
          return;
      }
  
      if ((err = esp_bluedroid_enable()) != ESP_OK) {
          ESP_LOGE(BT_AV_TAG, "%s enable bluedroid failed: %s\n", __func__, esp_err_to_name(err));
          return;
      }
  
      /* create application task */
      bt_app_task_start_up();
  
      /* Bluetooth device name, connection mode and profile set up */
      bt_app_work_dispatch(bt_av_hdl_stack_evt, BT_APP_EVT_STACK_UP, NULL, 0, NULL);
  
      /* Set default parameters for Secure Simple Pairing */
      esp_bt_sp_param_t param_type = ESP_BT_SP_IOCAP_MODE;
      esp_bt_io_cap_t iocap = ESP_BT_IO_CAP_IO;
      esp_bt_gap_set_security_param(param_type, &iocap, sizeof(uint8_t));
  
      /*
       * Set default parameters for Legacy Pairing
       * Use fixed pin code
       */
      esp_bt_pin_type_t pin_type = ESP_BT_PIN_TYPE_FIXED;
      esp_bt_pin_code_t pin_code;
      pin_code[0] = '1';
      pin_code[1] = '2';
      pin_code[2] = '3';
      pin_code[3] = '4';
      esp_bt_gap_set_pin(pin_type, 4, pin_code);
  }
  
  void bt_app_gap_cb(esp_bt_gap_cb_event_t event, esp_bt_gap_cb_param_t *param)
  {
      switch (event) {
      case ESP_BT_GAP_AUTH_CMPL_EVT: {
          if (param->auth_cmpl.stat == ESP_BT_STATUS_SUCCESS) {
              ESP_LOGI(BT_AV_TAG, "authentication success: %s", param->auth_cmpl.device_name);
              esp_log_buffer_hex(BT_AV_TAG, param->auth_cmpl.bda, ESP_BD_ADDR_LEN);
          } else {
              ESP_LOGE(BT_AV_TAG, "authentication failed, status:%d", param->auth_cmpl.stat);
          }
          break;
      }
      case ESP_BT_GAP_CFM_REQ_EVT:
          ESP_LOGI(BT_AV_TAG, "ESP_BT_GAP_CFM_REQ_EVT Please compare the numeric value: %d", param->cfm_req.num_val);
          esp_bt_gap_ssp_confirm_reply(param->cfm_req.bda, true);
          break;
      case ESP_BT_GAP_KEY_NOTIF_EVT:
          ESP_LOGI(BT_AV_TAG, "ESP_BT_GAP_KEY_NOTIF_EVT passkey:%d", param->key_notif.passkey);
          break;
      case ESP_BT_GAP_KEY_REQ_EVT:
          ESP_LOGI(BT_AV_TAG, "ESP_BT_GAP_KEY_REQ_EVT Please enter passkey!");
          break;
      default: {
          ESP_LOGI(BT_AV_TAG, "event: %d", event);
          break;
      }
      }
      return;
  }
  static void bt_av_hdl_stack_evt(uint16_t event, void *p_param)
  {
      ESP_LOGD(BT_AV_TAG, "%s evt %d", __func__, event);
      switch (event) {
      case BT_APP_EVT_STACK_UP: {
          /* set up device name */
          char *dev_name = "ESP_SPEAKER";
          esp_bt_dev_set_device_name(dev_name);
  
          esp_bt_gap_register_callback(bt_app_gap_cb);
          /* initialize A2DP sink */
          esp_a2d_register_callback(&bt_app_a2d_cb);
          esp_a2d_sink_register_data_callback(bt_app_a2d_data_cb);
          esp_a2d_sink_init();
  
          /* initialize AVRCP controller */
          esp_avrc_ct_init();
          esp_avrc_ct_register_callback(bt_app_rc_ct_cb);
  
          /* set discoverable and connectable mode, wait to be connected */
          esp_bt_gap_set_scan_mode(ESP_BT_SCAN_MODE_CONNECTABLE_DISCOVERABLE);
          break;
      }
      default:
          ESP_LOGE(BT_AV_TAG, "%s unhandled evt %d", __func__, event);
          break;
      }
  }
  