Classic Bluetooth® L2CAP API
Application Example
Check bluetooth/bluedroid/classic_bt folder in ESP-IDF examples, which contains the following application:
- This is a BT_L2CAP demo. This demo can connect, send and receive L2CAP data bluetooth/bluedroid/classic_bt/bt_l2cap_client, bluetooth/bluedroid/classic_bt/bt_l2cap_server
API Reference
Header File
components/bt/host/bluedroid/api/include/api/esp_l2cap_bt_api.h
This header file can be included with:
#include "esp_l2cap_bt_api.h"
- This header file is a part of the API provided by the
btcomponent. To declare that your component depends onbt, add the following to your CMakeLists.txt:
REQUIRES btor
> PRIV_REQUIRES bt
Functions
esp_err_t esp_bt_l2cap_register_callback(esp_bt_l2cap_cb_t callback)
This function is called to init callbacks with L2CAP module.
参数
callback -- [in] pointer to the init callback function.
返回
ESP_OK: success
other: failed
esp_err_t esp_bt_l2cap_init(void)
This function is called to init L2CAP module. When the operation is completed, the callback function will be called with ESP_BT_L2CAP_INIT_EVT. This function should be called after esp_bluedroid_enable() completes successfully.
返回
ESP_OK: success
other: failed
esp_err_t esp_bt_l2cap_deinit(void)
This function is called to uninit l2cap module. The operation will close all active L2CAP connection first, then the callback function will be called with ESP_BT_L2CAP_CLOSE_EVT, and the number of ESP_BT_L2CAP_CLOSE_EVT is equal to the number of connection. When the operation is completed, the callback function will be called with ESP_BT_L2CAP_UNINIT_EVT. This function should be called after esp_bt_l2cap_init() completes successfully.
返回
ESP_OK: success
other: failed
esp_err_t esp_bt_l2cap_connect(esp_bt_l2cap_cntl_flags_t cntl_flag, uint16_t remote_psm, esp_bd_addr_t peer_bd_addr)
This function makes an L2CAP connection to a remote BD Address. When the connection is initiated or failed to initiate, the callback is called with ESP_BT_L2CAP_CL_INIT_EVT. When the connection is established or failed, the callback is called with ESP_BT_L2CAP_OPEN_EVT. This function must be called after esp_bt_l2cap_init() successful and before esp_bt_l2cap_deinit().
参数
cntl_flag -- [in] Lower 16-bit security settings mask.
remote_psm -- [in] Remote device bluetooth Profile PSM.
peer_bd_addr -- [in] Remote device bluetooth device address.
返回
ESP_OK: success
other: failed
esp_err_t esp_bt_l2cap_start_srv(esp_bt_l2cap_cntl_flags_t cntl_flag, uint16_t local_psm)
This function create a L2CAP server and starts listening for an L2CAP connection request from a remote Bluetooth device. When the server is started successfully, the callback is called with ESP_BT_L2CAP_START_EVT. When the connection is established, the callback is called with ESP_BT_L2CAP_OPEN_EVT. This function must be called after esp_bt_l2cap_init() successful and before esp_bt_l2cap_deinit().
参数
cntl_flag -- [in] Lower 16-bit security settings mask.
local_psm -- [in] Dynamic PSM.
返回
ESP_OK: success
other: failed
esp_err_t esp_bt_l2cap_stop_all_srv(void)
This function stops all L2CAP servers. The operation will close all active L2CAP connection first, then the callback function will be called with ESP_BT_L2CAP_CLOSE_EVT, and the number of ESP_BT_L2CAP_CLOSE_EVT is equal to the number of connection. When the operation is completed, the callback is called with ESP_BT_L2CAP_SRV_STOP_EVT. This function must be called after esp_bt_l2cap_init() successful and before esp_bt_l2cap_deinit().
返回
ESP_OK: success
other: failed
esp_err_t esp_bt_l2cap_stop_srv(uint16_t local_psm)
This function stops a specific L2CAP server. The operation will close all active L2CAP connection first on the specific L2CAP server, then the callback function will be called with ESP_BT_L2CAP_CLOSE_EVT, and the number of ESP_BT_L2CAP_CLOSE_EVT is equal to the number of connection. When the operation is completed, the callback is called with ESP_BT_L2CAP_SRV_STOP_EVT. This function must be called after esp_bt_l2cap_init() successful and before esp_bt_l2cap_deinit().
参数
local_psm -- [in] Dynamic PSM.
返回
ESP_OK: success
other: failed
esp_err_t esp_bt_l2cap_vfs_register(void)
This function is used to register VFS. Only supports write, read and close. This function must be called after esp_bt_l2cap_init() successful and before esp_bt_l2cap_deinit().
返回
ESP_OK: success
other: failed
esp_err_t esp_bt_l2cap_vfs_unregister(void)
This function is used to unregister VFS. This function must be called after esp_bt_l2cap_init() successful and before esp_bt_l2cap_deinit().
返回
ESP_OK: success
other: failed
Unions
union esp_bt_l2cap_cb_param_t
#include <esp_l2cap_bt_api.h>
L2CAP callback parameters union.
Public Members
struct esp_bt_l2cap_cb_param_t::l2cap_init_evt_param init
L2CAP callback param of ESP_BT_L2CAP_INIT_EVT
struct esp_bt_l2cap_cb_param_t::l2cap_uninit_evt_param uninit
L2CAP callback param of ESP_BT_L2CAP_UNINIT_EVT
struct esp_bt_l2cap_cb_param_t::l2cap_open_evt_param open
L2CAP callback param of ESP_BT_L2CAP_OPEN_EVT
struct esp_bt_l2cap_cb_param_t::l2cap_close_evt_param close
L2CAP callback param of ESP_BT_L2CAP_CLOSE_EVT
struct esp_bt_l2cap_cb_param_t::l2cap_start_evt_param start
L2CAP callback param of ESP_BT_L2CAP_START_EVT
struct esp_bt_l2cap_cb_param_t::l2cap_cl_init_evt_param cl_init
L2CAP callback param of ESP_BT_L2CAP_CL_INIT_EVT
struct esp_bt_l2cap_cb_param_t::l2cap_srv_stop_evt_param srv_stop
L2CAP callback param of ESP_BT_L2CAP_SRV_STOP_EVT
struct l2cap_cl_init_evt_param
#include <esp_l2cap_bt_api.h>
ESP_BT_L2CAP_CL_INIT_EVT.
Public Members
esp_bt_l2cap_status_t status
status
uint32_t handle
The connection handle
uint8_t sec_id
security ID used by this server
struct l2cap_close_evt_param
#include <esp_l2cap_bt_api.h>
ESP_BT_L2CAP_CLOSE_EVT.
Public Members
esp_bt_l2cap_status_t status
status
uint32_t handle
The connection handle
bool async
FALSE, if local initiates disconnect
struct l2cap_init_evt_param
#include <esp_l2cap_bt_api.h>
ESP_BT_L2CAP_INIT_EVT.
Public Members
esp_bt_l2cap_status_t status
status
struct l2cap_open_evt_param
#include <esp_l2cap_bt_api.h>
ESP_BT_L2CAP_OPEN_EVT.
Public Members
esp_bt_l2cap_status_t status
status
uint32_t handle
The connection handle
int fd
File descriptor
esp_bd_addr_t rem_bda
The peer address
int32_t tx_mtu
The transmit MTU
struct l2cap_srv_stop_evt_param
#include <esp_l2cap_bt_api.h>
ESP_BT_L2CAP_SRV_STOP_EVT.
Public Members
esp_bt_l2cap_status_t status
status
uint8_t psm
local psm
struct l2cap_start_evt_param
#include <esp_l2cap_bt_api.h>
ESP_BT_L2CAP_START_EVT.
Public Members
esp_bt_l2cap_status_t status
status
uint32_t handle
The connection handle
uint8_t sec_id
security ID used by this server
struct l2cap_uninit_evt_param
#include <esp_l2cap_bt_api.h>
ESP_BT_L2CAP_UNINIT_EVT.
Public Members
esp_bt_l2cap_status_t status
status
Macros
ESP_BT_L2CAP_SEC_NONE
Security Setting Mask. Use these three mask mode:
ESP_BT_L2CAP_SEC_NONE
ESP_BT_L2CAP_SEC_AUTHENTICATE
(ESP_BT_L2CAP_SEC_ENCRYPT|ESP_BT_L2CAP_SEC_AUTHENTICATE) No security
ESP_BT_L2CAP_SEC_AUTHORIZE
Authorization required
ESP_BT_L2CAP_SEC_AUTHENTICATE
Authentication required
ESP_BT_L2CAP_SEC_ENCRYPT
Encryption required
Type Definitions
typedef uint32_t esp_bt_l2cap_cntl_flags_t
typedef void (*esp_bt_l2cap_cb_t)(esp_bt_l2cap_cb_event_t event, esp_bt_l2cap_cb_param_t *param)
L2CAP callback function type.
Param event
Event type
Param param
Point to callback parameter, currently is union type
Enumerations
enum esp_bt_l2cap_status_t
L2CAP operation success and failure codes.
Values:
enumerator ESP_BT_L2CAP_SUCCESS
Successful operation.
enumerator ESP_BT_L2CAP_FAILURE
Generic failure.
enumerator ESP_BT_L2CAP_BUSY
Temporarily can not handle this request.
enumerator ESP_BT_L2CAP_NO_RESOURCE
No more resource
enumerator ESP_BT_L2CAP_NEED_INIT
L2CAP module shall init first
enumerator ESP_BT_L2CAP_NEED_DEINIT
L2CAP module shall deinit first
enumerator ESP_BT_L2CAP_NO_CONNECTION
Connection may have been closed
enumerator ESP_BT_L2CAP_NO_SERVER
No server
enum esp_bt_l2cap_cb_event_t
L2CAP callback function events.
Values:
enumerator ESP_BT_L2CAP_INIT_EVT
When L2CAP is initialized, the event comes
enumerator ESP_BT_L2CAP_UNINIT_EVT
When L2CAP is deinitialized, the event comes
enumerator ESP_BT_L2CAP_OPEN_EVT
When L2CAP Client connection open, the event comes
enumerator ESP_BT_L2CAP_CLOSE_EVT
When L2CAP connection closed, the event comes
enumerator ESP_BT_L2CAP_START_EVT
When L2CAP server started, the event comes
enumerator ESP_BT_L2CAP_CL_INIT_EVT
When L2CAP client initiated a connection, the event comes
enumerator ESP_BT_L2CAP_SRV_STOP_EVT
When L2CAP server stopped, the event comes