# Controller & HCI

[中文]

## Application Examples

- bluetooth/hci/ble_adv_scan_combined demonstrates how to use Bluetooth capabilities for advertising and scanning with a virtual Host Controller Interface (HCI). This example shows how to implement some host functionalities without a host and displays scanned advertising reports from other devices.

- bluetooth/hci/controller_hci_uart_esp32 demonstrates how to configure the Bluetooth LE Controller's HCI to communicate over UART on ESP32, enabling communication with an external Bluetooth host stack.

- bluetooth/hci/controller_vhci_ble_adv demonstrates how to use the ESP-IDF VHCI ble_advertising app to perform advertising without a host and display received HCI events from the controller.

## API Reference

### Header File

- components/bt/include/esp32/include/esp_bt.h

- This header file can be included with:

  >     #include "esp_bt.h"

- This header file is a part of the API provided by the `bt` component. To declare that your component depends on `bt`, add the following to your CMakeLists.txt:

  >     REQUIRES bt

  > or

  >     PRIV_REQUIRES bt

### Functions

esp_err_t esp_bt_controller_init(esp_bt_controller_config_t *cfg)

  Initialize the Bluetooth Controller to allocate tasks and other resources.

  Note

  This function should be called only once, before any other Bluetooth functions.

  Parameters:

    cfg -- [in] Initial Bluetooth Controller configuration

  Returns:

    - ESP_OK: Success

    - ESP_ERR_INVALID_STATE: Invalid Bluetooth Controller state

    - ESP_ERR_INVALID_ARG: Invalid arguments

    - ESP_ERR_NO_MEM: Out of memory

esp_err_t esp_bt_controller_deinit(void)

  De-initialize Bluetooth Controller to free resources and delete tasks.

  Note

  1. You should stop advertising and scanning, and disconnect all existing connections before de-initializing Bluetooth Controller.

  2. This function should be called after `esp_bt_controller_disable` if the Controller was enabled before.

  3. This function should be called only once, after any other Bluetooth functions.

  Returns:

    - ESP_OK: Success

    - ESP_ERR_INVALID_STATE: Invalid Bluetooth Controller state

esp_err_t esp_bt_controller_enable(esp_bt_mode_t mode)

  Enable Bluetooth Controller.

  For API compatibility, retain this argument. This mode must match the mode specified in the `cfg` of `esp_bt_controller_init()`.

  Note

  1. Bluetooth Controller cannot be enabled in `ESP_BT_CONTROLLER_STATUS_IDLE` status. It has to be initialized first.

  2. Due to a known issue, you cannot call `esp_bt_controller_enable()` for the second time to change the Controller mode dynamically. To change the Controller mode, call `esp_bt_controller_disable()` and then call `esp_bt_controller_enable()` with the new mode.

  Parameters:

    mode -- [in] The Bluetooth Controller mode (BLE/Classic Bluetooth/BTDM) to enable

  Returns:

    - ESP_OK: Success

    - ESP_ERR_INVALID_STATE: Invalid Bluetooth Controller state

    - ESP_ERR_INVALID_ARG: Invalid arguments

esp_err_t esp_bt_controller_disable(void)

  Disable Bluetooth Controller.

  Returns:

    - ESP_OK: Success

    - ESP_ERR_INVALID_STATE: Invalid Bluetooth Controller state

esp_bt_controller_status_t esp_bt_controller_get_status(void)

  Get Bluetooth Controller status.

  Returns:

    - ESP_BT_CONTROLLER_STATUS_IDLE: The Controller is not initialized or has been de-initialized.

    - ESP_BT_CONTROLLER_STATUS_INITED: The Controller has been initialized, but not enabled or has been disabled.

    - ESP_BT_CONTROLLER_STATUS_ENABLED: The Controller has been initialized and enabled.

esp_err_t esp_bt_controller_mem_release(esp_bt_mode_t mode)

  Release the Controller memory as per the mode.

  This function releases the BSS, data and other sections of the Controller to heap. The total size is about 70 KB.

  If you never intend to use Bluetooth in a current boot-up cycle, calling `esp_bt_controller_mem_release(ESP_BT_MODE_BTDM)` could release the BSS and data consumed by both Classic Bluetooth and BLE Controller to heap.

  If you intend to use BLE only, calling `esp_bt_controller_mem_release(ESP_BT_MODE_CLASSIC_BT)` could release the BSS and data consumed by Classic Bluetooth Controller. You can then continue using BLE.

  If you intend to use Classic Bluetooth only, calling `esp_bt_controller_mem_release(ESP_BT_MODE_BLE)` could release the BSS and data consumed by BLE Controller. You can then continue using Classic Bluetooth.

  Note

  1. This function is optional and should be called only if you want to free up memory for other components.

  2. This function should only be called when the Controller is in `ESP_BT_CONTROLLER_STATUS_IDLE` status.

  3. Once Bluetooth Controller memory is released, the process cannot be reversed. This means you cannot use the Bluetooth Controller mode that you have released using this function.

  4. If your firmware will upgrade the Bluetooth Controller mode later (such as switching from BLE to Classic Bluetooth or from disabled to enabled), then do not call this function.

  Parameters:

    mode -- [in] The Bluetooth Controller mode

  Returns:

    - ESP_OK: Success

    - ESP_ERR_INVALID_STATE: Invalid Bluetooth Controller state

    - ESP_ERR_NOT_FOUND: Requested resource not found

esp_err_t esp_bt_mem_release(esp_bt_mode_t mode)

  Release the Controller memory, BSS and data section of the Classic Bluetooth/BLE Host stack as per the mode.

  This function first releases Controller memory by internally calling `esp_bt_controller_mem_release()`, then releases Host memory.

  If you never intend to use Bluetooth in a current boot-up cycle, calling `esp_bt_mem_release(ESP_BT_MODE_BTDM)` could release the BSS and data consumed by both Classic Bluetooth and BLE stack to heap.

  If you intend to use BLE only, calling `esp_bt_mem_release(ESP_BT_MODE_CLASSIC_BT)` could release the BSS and data consumed by Classic Bluetooth. You can then continue using BLE.

  If you intend to use Classic Bluetooth only, calling `esp_bt_mem_release(ESP_BT_MODE_BLE)` could release the BSS and data consumed by BLE. You can then continue using Classic Bluetooth.

  For example, if you only use Bluetooth for setting the Wi-Fi configuration, and do not use Bluetooth in the rest of the product operation, after receiving the Wi-Fi configuration, you can disable/de-init Bluetooth and release its memory. Below is the sequence of APIs to be called for such scenarios:

        esp_bluedroid_disable();
        esp_bluedroid_deinit();
        esp_bt_controller_disable();
        esp_bt_controller_deinit();
        esp_bt_mem_release(ESP_BT_MODE_BTDM);

  Note

  1. This function is optional and should be called only if you want to free up memory for other components.

  2. This function should only be called when the Controller is in `ESP_BT_CONTROLLER_STATUS_IDLE` status.

  3. Once Bluetooth Controller memory is released, the process cannot be reversed. This means you cannot use the Bluetooth Controller mode that you have released using this function.

  4. If your firmware will upgrade the Bluetooth Controller mode later (such as switching from BLE to Classic Bluetooth or from disabled to enabled), then do not call this function.

  Parameters:

    mode -- [in] The Bluetooth Controller mode

  Returns:

    - ESP_OK: Success

    - ESP_ERR_INVALID_STATE: Invalid Bluetooth Controller state

    - ESP_ERR_NOT_FOUND: Requested resource not found

esp_err_t esp_bt_sleep_enable(void)

  Enable Bluetooth modem sleep.

  There are currently two options for Bluetooth modem sleep: ORIG mode and EVED mode. The latter is intended for BLE only. The modem sleep mode could be configured in menuconfig.

  In ORIG mode, if there is no event to process, the Bluetooth Controller will periodically switch off some components and pause operation, then wake up according to the scheduled interval and resume work. It can also wakeup earlier upon external request using function `esp_bt_controller_wakeup_request()`.

  Note

  This function shall not be invoked before `esp_bt_controller_enable()`.

  Returns:

    - ESP_OK: Success

    - ESP_ERR_INVALID_STATE: Invalid Bluetooth Controller state

    - ESP_ERR_NOT_SUPPORTED: Operation or feature not supported

esp_err_t esp_bt_sleep_disable(void)

  Disable Bluetooth modem sleep.

  Note

  1. Bluetooth Controller will not be allowed to enter modem sleep after calling this function.

  2. In ORIG modem sleep mode, calling this function may not immediately wake up the Controller if it is currently dormant. In this case, `esp_bt_controller_wakeup_request()` can be used to shorten the wake-up time.

  3. This function shall not be invoked before `esp_bt_controller_enable()`.

  Returns:

    - ESP_OK: Success

    - ESP_ERR_INVALID_STATE: Invalid Bluetooth Controller state

    - ESP_ERR_NOT_SUPPORTED: The modem sleep mode is not supported

esp_err_t esp_ble_tx_power_set(esp_ble_power_type_t power_type, esp_power_level_t power_level)

  Set BLE TX power.

  Note

  Connection TX power should only be set after the connection is established.

  Parameters:

    - power_type -- [in] The type of TX power. It could be Advertising, Connection, Default, etc.

    - power_level -- [in] Power level (index) corresponding to the absolute value (dBm)

  Returns:

    - ESP_OK: Success

    - ESP_ERR_INVALID_ARG: Invalid argument

esp_power_level_t esp_ble_tx_power_get(esp_ble_power_type_t power_type)

  Get BLE TX power.

  Note

  Connection TX power should only be retrieved after the connection is established.

  Parameters:

    power_type -- [in] The type of TX power. It could be Advertising/Connection/Default and etc.

  Returns:

    - Power level

esp_err_t esp_ble_scan_duplicate_list_flush(void)

  Manually clear the BLE scan duplicate list.

  Note

  1. This function name is incorrectly spelled, it will be fixed in release 5.x version.

  2. The scan duplicate list will be automatically cleared when the maximum amount of devices in the filter is reached. The amount of devices in the filter can be configured in menuconfig.

  Returns:

    - ESP_OK: Success

    - ESP_ERR_INVALID_STATE: Invalid Bluetooth Controller state

esp_err_t esp_ble_scan_dupilcate_list_flush(void)

esp_err_t esp_bredr_tx_power_set(esp_power_level_t min_power_level, esp_power_level_t max_power_level)

  Set BR/EDR TX power.

  BR/EDR power control will use the power within the range of minimum value and maximum value. The power level will affect the global BR/EDR TX power for operations such as inquiry, page, and connection.

  Note

  1. Please call this function after `esp_bt_controller_enable()` and before any functions that cause RF transmission, such as performing discovery, profile initialization, and so on.

  2. For BR/EDR to use the new TX power for inquiry, call this function before starting an inquiry. If BR/EDR is already inquiring, restart the inquiry after calling this function.

  Parameters:

    - min_power_level -- [in] The minimum power level. The default value is `ESP_PWR_LVL_N0`.

    - max_power_level -- [in] The maximum power level. The default value is `ESP_PWR_LVL_P3`.

  Returns:

    - ESP_OK: Success

    - ESP_ERR_INVALID_ARG: Invalid argument

    - ESP_ERR_INVALID_STATE: Invalid Bluetooth Controller state

esp_err_t esp_bredr_tx_power_get(esp_power_level_t *min_power_level, esp_power_level_t *max_power_level)

  Get BR/EDR TX power.

  The corresponding power levels will be stored into the arguments.

  Parameters:

    - min_power_level -- [out] Pointer to store the minimum power level

    - max_power_level -- [out] The maximum power level

  Returns:

    - ESP_OK: Success

    - ESP_ERR_INVALID_ARG: Invalid argument

esp_err_t esp_bredr_sco_datapath_set(esp_sco_data_path_t data_path)

  Set BR/EDR default SCO data path.

  Note

  This function should be called after the Controller is enabled, and before (e)SCO link is established.

  Parameters:

    data_path -- [in] SCO data path

  Returns:

    - ESP_OK: Success

    - ESP_ERR_INVALID_STATE: Invalid Bluetooth Controller state

bool esp_vhci_host_check_send_available(void)

  Check whether the Controller is ready to receive the packet.

  If the return value is True, the Host can send the packet to the Controller.

  Note

  This function should be called before each `esp_vhci_host_send_packet()`.

  Returns:

    True if the Controller is ready to receive packets; false otherwise

void esp_vhci_host_send_packet(uint8_t *data, uint16_t len)

  Send the packet to the Controller.

  Note

  1. This function shall not be called within a critical section or when the scheduler is suspended.

  2. This function should be called only if `esp_vhci_host_check_send_available()` returns True.

  Parameters:

    - data -- [in] Pointer to the packet data

    - len -- [in] The packet length

esp_err_t esp_vhci_host_register_callback(const esp_vhci_host_callback_t *callback)

  Register the VHCI callback funations defined in `esp_vhci_host_callback` structure.

  Parameters:

    callback -- [in] `esp_vhci_host_callback` type variable

  Returns:

    - ESP_OK: Success

    - ESP_FAIL: Failure

esp_bt_sleep_clock_t esp_bt_get_lpclk_src(void)

  Get the Bluetooth module sleep clock source.

  Note

  This function should be called after `esp_bt_controller_init()`

  Returns:

    - Clock source used in Bluetooth low power mode

esp_err_t esp_bt_set_lpclk_src(esp_bt_sleep_clock_t lpclk)

  Set the Bluetooth module sleep clock source.

  Note

  This function should be called before `esp_bt_controller_init()`

  Parameters:

    lpclk -- [in] Bluetooth sleep clock source

  Returns:

    - ESP_OK: Success

    - ESP_ERR_INVALID_ARG: Invalid argument

### Structures

struct esp_bt_controller_config_t

  Bluetooth Controller config options.

  Note

  1. For parameters configurable through menuconfig, it is recommended to adjust them via the menuconfig interface. Please refer to menuconfig for details on the range and default values.

  2. It is not recommended to modify the values for parameters which are not configurable through menuconfig.

  Public Members

  uint16_t controller_task_stack_size

    Bluetooth Controller task stack size in bytes

  uint8_t controller_task_prio

    Bluetooth Controller task priority

  uint8_t hci_uart_no

    UART number as HCI I/O interface. Configurable in menuconfig.

    - 1 - URAT 1 (default)

    - 2 - URAT 2

  uint32_t hci_uart_baudrate

    UART baudrate. Configurable in menuconfig.

    - Range: 115200 - 921600

    - Default: 921600

  uint8_t scan_duplicate_mode

    Scan duplicate filtering mode. Configurable in menuconfig.

    - 0 - Normal scan duplicate filtering mode (default)

    - 1 - Special scan duplicate filtering mode for BLE Mesh

  uint8_t scan_duplicate_type

    Scan duplicate filtering type. If `scan_duplicate_mode` is set to 1, this parameter will be ignored. Configurable in menuconfig.

    - 0 - Filter scan duplicates by device address only (default)

    - 1 - Filter scan duplicates by advertising data only, even if they originate from different devices.

    - 2 - Filter scan duplicated by device address and advertising data.

  uint16_t normal_adv_size

    Maximum number of devices in scan duplicate filtering list. Configurable in menuconfig

    - Range: 10 - 1000

    - Default: 100

  uint16_t mesh_adv_size

    Maximum number of Mesh advertising packets in scan duplicate filtering list. Configurable in menuconfig

    - Range: 10 - 1000

    - Default: 100

  uint16_t send_adv_reserved_size

    Controller minimum memory value in bytes. Internal use only

  uint32_t controller_debug_flag

    Controller debug log flag. Internal use only

  uint8_t mode

    Controller mode. Configurable in menuconfig

    - 1 - BLE mode

    - 2 - Classic Bluetooth mode

    - 3 - Dual mode

    - 4 - Others: Invalid

  uint8_t ble_max_conn

    Maximum number of BLE connections. Configurable in menuconfig

    - Range: 1 - 9

    - Default: 3

  uint8_t bt_max_acl_conn

    Maximum number of BR/EDR ACL connections. Configurable in menuconfig

    - Range: 1 - 7

    - Default: 2

  uint8_t bt_sco_datapath

    SCO data path. Configurable in menuconfig

    - 0 - HCI module (default)

    - 1 - PCM module

  bool auto_latency

    True if BLE auto latency is enabled, used to enhance Classic Bluetooth performance in the Dual mode; false otherwise (default). Configurable in menuconfig

  bool bt_legacy_auth_vs_evt

    True if BR/EDR Legacy Authentication Vendor Specific Event is enabled (default in the classic bluetooth or Dual mode), which is required to protect from BIAS attack; false otherwise. Configurable in menuconfig

  uint8_t bt_max_sync_conn

    Maximum number of BR/EDR synchronous connections. Configurable in menuconfig

    - Range: 0 - 3

    - Default: 0

  uint8_t ble_sca

    BLE low power crystal accuracy index. Configurable in menuconfig

    - 0 - `BTDM_BLE_DEFAULT_SCA_500PPM`

    - 1 - `BTDM_BLE_DEFAULT_SCA_250PPM` (default)

  uint8_t pcm_role

    PCM role. Configurable in menuconfig

    - 0 - PCM master (default)

    - 1 - PCM slave (default)

  uint8_t pcm_polar

    PCM polarity (falling clk edge & rising clk edge). Configurable in menuconfig

    - 0 - Falling Edge (default)

    - 1 - Rising Edge

  uint8_t pcm_fsyncshp

    Physical shape of the PCM Frame Synchronization signal. Configurable in menuconfig

    - 0 - Stereo Mode (default)

    - 1 - Mono Mode 1

    - 2 - Mono Mode 2

  bool hli

    True if using high-level (level 4) interrupt (default); false otherwise. Configurable in menuconfig

  uint8_t enc_key_sz_min

    Minimum size of the encryption key

    - Range: 7 - 16

    - Default: 7

  uint16_t dup_list_refresh_period

    Scan duplicate filtering list refresh period in seconds. Configurable in menuconfig

    - Range: 0 - 100 seconds

    - Default: 0 second

  bool ble_scan_backoff

    True if BLE scan backoff is enabled; false otherwise (default). Configurable in menuconfig

  uint8_t ble_llcp_disc_flag

    Flag indicating whether the Controller disconnects after Instant Passed (0x28) error occurs. Configurable in menuconfig.

    - The Controller does not disconnect after Instant Passed (0x28) by default.

  bool ble_aa_check

    True if adds a verification step for the Access Address within the `CONNECT_IND` PDU; false otherwise (default). Configurable in menuconfig

  uint8_t ble_chan_ass_en

    True if BLE channel assessment is enabled (default), false otherwise. Configurable in menuconfig

  uint8_t ble_ping_en

    True if BLE ping procedure is enabled (default), false otherwise. Configurable in menuconfig

  uint32_t magic

    Magic number

struct esp_vhci_host_callback

  Virtual HCI (VHCI) callback functions to notify the Host on the next operation.

  Public Members

  void (*notify_host_send_available)(void)

    Callback to notify the Host that the Controller is ready to receive the packet

  int (*notify_host_recv)(uint8_t *data, uint16_t len)

    Callback to notify the Host that the Controller has a packet to send

### Macros

ESP_BT_CONTROLLER_CONFIG_MAGIC_VAL

  Internal use only.

  Note

  Please do not modify this value

BT_CONTROLLER_INIT_CONFIG_DEFAULT()

  Default Bluetooth Controller configuration.

### Type Definitions

typedef struct esp_vhci_host_callback esp_vhci_host_callback_t

  Virtual HCI (VHCI) callback functions to notify the Host on the next operation.

### Enumerations

enum esp_bt_mode_t

  Bluetooth Controller mode.

  Values:

  enumerator ESP_BT_MODE_IDLE

    Bluetooth is not operating.

  enumerator ESP_BT_MODE_BLE

    Bluetooth is operating in BLE mode.

  enumerator ESP_BT_MODE_CLASSIC_BT

    Bluetooth is operating in Classic Bluetooth mode.

  enumerator ESP_BT_MODE_BTDM

    Bluetooth is operating in Dual mode.

enum esp_ble_sca_t

  BLE sleep clock accuracy (SCA)

  Note

  Currently only ESP_BLE_SCA_500PPM and ESP_BLE_SCA_250PPM are supported.

  Values:

  enumerator ESP_BLE_SCA_500PPM

    BLE SCA at 500 ppm

  enumerator ESP_BLE_SCA_250PPM

    BLE SCA at 250 ppm

  enumerator ESP_BLE_SCA_150PPM

    BLE SCA at 150 ppm

  enumerator ESP_BLE_SCA_100PPM

    BLE SCA at 100 ppm

  enumerator ESP_BLE_SCA_75PPM

    BLE SCA at 75 ppm

  enumerator ESP_BLE_SCA_50PPM

    BLE SCA at 50 ppm

  enumerator ESP_BLE_SCA_30PPM

    BLE SCA at 30 ppm

  enumerator ESP_BLE_SCA_20PPM

    BLE SCA at 20 ppm

enum esp_bt_controller_status_t

  Bluetooth Controller status.

  Values:

  enumerator ESP_BT_CONTROLLER_STATUS_IDLE

    The Controller is not initialized or has been de-initialized.

  enumerator ESP_BT_CONTROLLER_STATUS_INITED

    The Controller has been initialized, but not enabled or has been disabled.

  enumerator ESP_BT_CONTROLLER_STATUS_ENABLED

    The Controller has been initialized and enabled.

  enumerator ESP_BT_CONTROLLER_STATUS_NUM

    Number of Controller statuses

enum esp_ble_power_type_t

  BLE TX power type.

  Note

  1. The connection TX power can only be set after the connection is established. After disconnecting, the corresponding TX power will not be affected.

  2. `ESP_BLE_PWR_TYPE_DEFAULT` can be used to set the TX power for power types that have not been set before. It will not affect the TX power values which have been set for the ADV/SCAN/CONN0-8 power types.

  3. If none of power type is set, the system will use `ESP_PWR_LVL_P3` as default for all power types.

  Values:

  enumerator ESP_BLE_PWR_TYPE_CONN_HDL0

    TX power for connection handle 0

  enumerator ESP_BLE_PWR_TYPE_CONN_HDL1

    TX power for connection handle 1

  enumerator ESP_BLE_PWR_TYPE_CONN_HDL2

    TX power for connection handle 2

  enumerator ESP_BLE_PWR_TYPE_CONN_HDL3

    TX power for connection handle 3

  enumerator ESP_BLE_PWR_TYPE_CONN_HDL4

    TX power for connection handle 4

  enumerator ESP_BLE_PWR_TYPE_CONN_HDL5

    TX power for connection handle 5

  enumerator ESP_BLE_PWR_TYPE_CONN_HDL6

    TX power for connection handle 6

  enumerator ESP_BLE_PWR_TYPE_CONN_HDL7

    TX power for connection handle 7

  enumerator ESP_BLE_PWR_TYPE_CONN_HDL8

    TX power for connection handle 8

  enumerator ESP_BLE_PWR_TYPE_ADV

    TX power for advertising

  enumerator ESP_BLE_PWR_TYPE_SCAN

    TX power for scan

  enumerator ESP_BLE_PWR_TYPE_DEFAULT

    Default TX power type, which can be used to set the TX power for power types that have not been set before.

  enumerator ESP_BLE_PWR_TYPE_NUM

    Number of types

enum esp_power_level_t

  Bluetooth TX power level (index). Each index corresponds to a specific power value in dBm.

  Values:

  enumerator ESP_PWR_LVL_N12

    Corresponding to -12 dBm

  enumerator ESP_PWR_LVL_N9

    Corresponding to -9 dBm

  enumerator ESP_PWR_LVL_N6

    Corresponding to -6 dBm

  enumerator ESP_PWR_LVL_N3

    Corresponding to -3 dBm

  enumerator ESP_PWR_LVL_N0

    Corresponding to 0 dBm

  enumerator ESP_PWR_LVL_P3

    Corresponding to +3 dBm

  enumerator ESP_PWR_LVL_P6

    Corresponding to +6 dBm

  enumerator ESP_PWR_LVL_P9

    Corresponding to +9 dBm

  enumerator ESP_PWR_LVL_N14

    Backward compatibility! Setting to -14 dBm will actually result in -12 dBm

  enumerator ESP_PWR_LVL_N11

    Backward compatibility! Setting to -11 dBm will actually result in -9 dBm

  enumerator ESP_PWR_LVL_N8

    Backward compatibility! Setting to -8 dBm will actually result in -6 dBm

  enumerator ESP_PWR_LVL_N5

    Backward compatibility! Setting to -5 dBm will actually result in -3 dBm

  enumerator ESP_PWR_LVL_N2

    Backward compatibility! Setting to -2 dBm will actually result in 0 dBm

  enumerator ESP_PWR_LVL_P1

    Backward compatibility! Setting to +1 dBm will actually result in +3 dBm

  enumerator ESP_PWR_LVL_P4

    Backward compatibility! Setting to +4 dBm will actually result in +6 dBm

  enumerator ESP_PWR_LVL_P7

    Backward compatibility! Setting to +7 dBm will actually result in +9 dBm

enum esp_sco_data_path_t

  Bluetooth audio data transport path.

  Values:

  enumerator ESP_SCO_DATA_PATH_HCI

    data over HCI transport

  enumerator ESP_SCO_DATA_PATH_PCM

    data over PCM interface

enum esp_bt_sleep_clock_t

  Bluetooth sleep clock.

  Values:

  enumerator ESP_BT_SLEEP_CLOCK_NONE

    Sleep clock not configured

  enumerator ESP_BT_SLEEP_CLOCK_MAIN_XTAL

    SoC main crystal

  enumerator ESP_BT_SLEEP_CLOCK_EXT_32K_XTAL

    External 32.768kHz crystal/oscillator

## HCI Vendor-specific (VS) Commands

Espressif's HCI VS commands are exclusively designed for use with Espressif's Bluetooth Host stack or internal debugging purposes. Application developers should not initialize or invoke these VS commands in their applications. Please refer to HCI Vendor-specific (VS) Commands for detailed information.

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