SPP API

Application Examples

  • bluetooth/bluedroid/classic_bt/bt_spp_acceptor demonstrates how to use Bluetooth capabilities to create a Serial Port Protocol (SPP) acceptor that acts as a server and integrate Secure Simple Pairing (SSP). This example also includes a demo for communicating with an SPP initiator that acts as a client.

  • bluetooth/bluedroid/classic_bt/bt_spp_initiator demonstrates how to use Bluetooth capabilities to create an SPP initiator that performs as a client and integrate SSP. This example also includes a demo for communicating with an SPP acceptor that acts as a server.

  • bluetooth/bluedroid/classic_bt/bt_spp_vfs_initiator demonstrates how to use SPP APIs to create an SPP initiator that acts as a client and communicates with an SPP acceptor, using Virtual File System (VFS) interface to send and receive data.

API Reference

Header File

  • components/bt/host/bluedroid/api/include/api/esp_spp_api.h

  • This header file can be included with:

    #include "esp_spp_api.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_spp_register_callback(esp_spp_cb_t callback)

This function is called to init callbacks with SPP module.

Parameters

callback -- [in] pointer to the init callback function.

Returns

  • ESP_OK: success

  • other: failed

esp_err_t esp_spp_init(esp_spp_mode_t mode)

This function is called to init SPP module. When the operation is completed, the callback function will be called with ESP_SPP_INIT_EVT. This function should be called after esp_bluedroid_enable() completes successfully.

Parameters

mode -- [in] Choose the mode of SPP, ESP_SPP_MODE_CB or ESP_SPP_MODE_VFS.

Returns

  • ESP_OK: success

  • other: failed

esp_err_t esp_spp_enhanced_init(const esp_spp_cfg_t *cfg)

This function is called to init SPP module. When the operation is completed, the callback function will be called with ESP_SPP_INIT_EVT. This function should be called after esp_bluedroid_enable() completes successfully.

Note

The member variable enable_l2cap_etrm in esp_spp_cfg_t can affect all L2CAP channel configurations of the upper layer RFCOMM protocol.

Parameters

cfg -- [in] SPP configuration.

Returns

  • ESP_OK: success

  • other: failed

esp_err_t esp_spp_deinit(void)

This function is called to uninit SPP module. The operation will close all active SPP connection first, then the callback function will be called with ESP_SPP_CLOSE_EVT, and the number of ESP_SPP_CLOSE_EVT is equal to the number of connection. When the operation is completed, the callback function will be called with ESP_SPP_UNINIT_EVT. This function should be called after esp_spp_init()/esp_spp_enhanced_init() completes successfully.

Returns

  • ESP_OK: success

  • other: failed

esp_err_t esp_spp_start_discovery(esp_bd_addr_t bd_addr)

This function is called to performs service discovery for the services provided by the given peer device. When the operation is completed, the callback function will be called with ESP_SPP_DISCOVERY_COMP_EVT. This function must be called after esp_spp_init()/esp_spp_enhanced_init() successful and before esp_spp_deinit().

Parameters

bd_addr -- [in] Remote device bluetooth device address.

Returns

  • ESP_OK: success

  • other: failed

esp_err_t esp_spp_connect(esp_spp_sec_t sec_mask, esp_spp_role_t role, uint8_t remote_scn, esp_bd_addr_t peer_bd_addr)

This function makes an SPP connection to a remote BD Address. When the connection is initiated or failed to initiate, the callback is called with ESP_SPP_CL_INIT_EVT. When the connection is established or failed, the callback is called with ESP_SPP_OPEN_EVT. This function must be called after esp_spp_init()/esp_spp_enhanced_init() successful and before esp_spp_deinit().

Parameters

  • sec_mask -- [in] Security Setting Mask. Suggest to use ESP_SPP_SEC_NONE, ESP_SPP_SEC_AUTHORIZE or ESP_SPP_SEC_AUTHENTICATE only.

  • role -- [in] Master or slave.

  • remote_scn -- [in] Remote device bluetooth device SCN.

  • peer_bd_addr -- [in] Remote device bluetooth device address.

Returns

  • ESP_OK: success

  • other: failed

esp_err_t esp_spp_disconnect(uint32_t handle)

This function closes an SPP connection. When the operation is completed, the callback function will be called with ESP_SPP_CLOSE_EVT. This function must be called after esp_spp_init()/esp_spp_enhanced_init() successful and before esp_spp_deinit().

Parameters

handle -- [in] The connection handle.

Returns

  • ESP_OK: success

  • other: failed

esp_err_t esp_spp_start_srv(esp_spp_sec_t sec_mask, esp_spp_role_t role, uint8_t local_scn, const char *name)

This function create a SPP server and starts listening for an SPP connection request from a remote Bluetooth device. When the server is started successfully, the callback is called with ESP_SPP_START_EVT. When the connection is established, the callback is called with ESP_SPP_SRV_OPEN_EVT. This function must be called after esp_spp_init()/esp_spp_enhanced_init() successful and before esp_spp_deinit().

Parameters

  • sec_mask -- [in] Security Setting Mask. Suggest to use ESP_SPP_SEC_NONE, ESP_SPP_SEC_AUTHORIZE or ESP_SPP_SEC_AUTHENTICATE only.

  • role -- [in] Master or slave.

  • local_scn -- [in] The specific channel you want to get. If channel is 0, means get any channel.

  • name -- [in] Server's name.

Returns

  • ESP_OK: success

  • other: failed

esp_err_t esp_spp_stop_srv(void)

This function stops all SPP servers. The operation will close all active SPP connection first, then the callback function will be called with ESP_SPP_CLOSE_EVT, and the number of ESP_SPP_CLOSE_EVT is equal to the number of connection. When the operation is completed, the callback is called with ESP_SPP_SRV_STOP_EVT. This function must be called after esp_spp_init()/esp_spp_enhanced_init() successful and before esp_spp_deinit().

Returns

  • ESP_OK: success

  • other: failed

esp_err_t esp_spp_stop_srv_scn(uint8_t scn)

This function stops a specific SPP server. The operation will close all active SPP connection first on the specific SPP server, then the callback function will be called with ESP_SPP_CLOSE_EVT, and the number of ESP_SPP_CLOSE_EVT is equal to the number of connection. When the operation is completed, the callback is called with ESP_SPP_SRV_STOP_EVT. This function must be called after esp_spp_init()/esp_spp_enhanced_init() successful and before esp_spp_deinit().

Parameters

scn -- [in] Server channel number.

Returns

  • ESP_OK: success

  • other: failed

esp_err_t esp_spp_write(uint32_t handle, int len, uint8_t *p_data)

This function is used to write data, only for ESP_SPP_MODE_CB. When this function need to be called repeatedly, it is strongly recommended to call this function again after the previous event ESP_SPP_WRITE_EVT is received and the parameter 'cong' is equal to false. If the previous event ESP_SPP_WRITE_EVT with parameter 'cong' is equal to true, the function can only be called again when the event ESP_SPP_CONG_EVT with parameter 'cong' equal to false is received. This function must be called after an connection between initiator and acceptor has been established.

Parameters

  • handle -- [in] The connection handle.

  • len -- [in] The length of the data written.

  • p_data -- [in] The data written.

Returns

  • ESP_OK: success

  • other: failed

esp_err_t esp_spp_vfs_register(void)

This function is used to register VFS. For now, SPP only supports write, read and close. When the operation is completed, the callback function will be called with ESP_SPP_VFS_REGISTER_EVT. This function must be called after esp_spp_init()/esp_spp_enhanced_init() successful and before esp_spp_deinit().

Returns

  • ESP_OK: success

  • other: failed

esp_err_t esp_spp_vfs_unregister(void)

This function is used to unregister VFS. When the operation is completed, the callback function will be called with ESP_SPP_VFS_UNREGISTER_EVT. This function must be called after esp_spp_vfs_register() successful and before esp_spp_deinit().

Returns

  • ESP_OK: success

  • other: failed

Unions

union esp_spp_cb_param_t
#include <esp_spp_api.h>

SPP callback parameters union.

Public Members

struct esp_spp_cb_param_t::spp_init_evt_param init

SPP callback param of SPP_INIT_EVT

struct esp_spp_cb_param_t::spp_uninit_evt_param uninit

SPP callback param of SPP_UNINIT_EVT

struct esp_spp_cb_param_t::spp_discovery_comp_evt_param disc_comp

SPP callback param of SPP_DISCOVERY_COMP_EVT

struct esp_spp_cb_param_t::spp_open_evt_param open

SPP callback param of ESP_SPP_OPEN_EVT

struct esp_spp_cb_param_t::spp_srv_open_evt_param srv_open

SPP callback param of ESP_SPP_SRV_OPEN_EVT

struct esp_spp_cb_param_t::spp_close_evt_param close

SPP callback param of ESP_SPP_CLOSE_EVT

struct esp_spp_cb_param_t::spp_start_evt_param start

SPP callback param of ESP_SPP_START_EVT

struct esp_spp_cb_param_t::spp_srv_stop_evt_param srv_stop

SPP callback param of ESP_SPP_SRV_STOP_EVT

struct esp_spp_cb_param_t::spp_cl_init_evt_param cl_init

SPP callback param of ESP_SPP_CL_INIT_EVT

struct esp_spp_cb_param_t::spp_write_evt_param write

SPP callback param of ESP_SPP_WRITE_EVT

struct esp_spp_cb_param_t::spp_data_ind_evt_param data_ind

SPP callback param of ESP_SPP_DATA_IND_EVT

struct esp_spp_cb_param_t::spp_cong_evt_param cong

SPP callback param of ESP_SPP_CONG_EVT

struct esp_spp_cb_param_t::spp_vfs_register_evt_param vfs_register

SPP callback param of ESP_SPP_VFS_REGISTER_EVT

struct esp_spp_cb_param_t::spp_vfs_unregister_evt_param vfs_unregister

SPP callback param of ESP_SPP_VFS_UNREGISTER_EVT

struct spp_cl_init_evt_param
#include <esp_spp_api.h>

ESP_SPP_CL_INIT_EVT.

Public Members

esp_spp_status_t status

status

uint32_t handle

The connection handle

uint8_t sec_id

security ID used by this server

bool use_co

TRUE to use co_rfc_data

struct spp_close_evt_param
#include <esp_spp_api.h>

ESP_SPP_CLOSE_EVT.

Public Members

esp_spp_status_t status

status

uint32_t port_status

PORT status

uint32_t handle

The connection handle

bool async

FALSE, if local initiates disconnect

struct spp_cong_evt_param
#include <esp_spp_api.h>

ESP_SPP_CONG_EVT.

Public Members

esp_spp_status_t status

status

uint32_t handle

The connection handle

bool cong

TRUE, congested. FALSE, uncongested

struct spp_data_ind_evt_param
#include <esp_spp_api.h>

ESP_SPP_DATA_IND_EVT.

Public Members

esp_spp_status_t status

status

uint32_t handle

The connection handle

uint16_t len

The length of data

uint8_t *data

The data received

struct spp_discovery_comp_evt_param
#include <esp_spp_api.h>

SPP_DISCOVERY_COMP_EVT.

Public Members

esp_spp_status_t status

status

uint8_t scn_num

The num of scn_num

uint8_t scn[ESP_SPP_MAX_SCN]

channel #

const char *service_name[ESP_SPP_MAX_SCN]

service_name

struct spp_init_evt_param
#include <esp_spp_api.h>

SPP_INIT_EVT.

Public Members

esp_spp_status_t status

status

struct spp_open_evt_param
#include <esp_spp_api.h>

ESP_SPP_OPEN_EVT.

Public Members

esp_spp_status_t status

status

uint32_t handle

The connection handle

int fd

The file descriptor only for ESP_SPP_MODE_VFS

esp_bd_addr_t rem_bda

The peer address

struct spp_srv_open_evt_param
#include <esp_spp_api.h>

ESP_SPP_SRV_OPEN_EVT.

Public Members

esp_spp_status_t status

status

uint32_t handle

The connection handle

uint32_t new_listen_handle

The new listen handle

int fd

The file descriptor only for ESP_SPP_MODE_VFS

esp_bd_addr_t rem_bda

The peer address

struct spp_srv_stop_evt_param
#include <esp_spp_api.h>

ESP_SPP_SRV_STOP_EVT.

Public Members

esp_spp_status_t status

status

uint8_t scn

Server channel number

struct spp_start_evt_param
#include <esp_spp_api.h>

ESP_SPP_START_EVT.

Public Members

esp_spp_status_t status

status

uint32_t handle

The connection handle

uint8_t sec_id

security ID used by this server

uint8_t scn

Server channel number

bool use_co

TRUE to use co_rfc_data

struct spp_uninit_evt_param
#include <esp_spp_api.h>

SPP_UNINIT_EVT.

Public Members

esp_spp_status_t status

status

struct spp_vfs_register_evt_param
#include <esp_spp_api.h>

ESP_SPP_VFS_REGISTER_EVT.

Public Members

esp_spp_status_t status

status

struct spp_vfs_unregister_evt_param
#include <esp_spp_api.h>

ESP_SPP_VFS_UNREGISTER_EVT.

Public Members

esp_spp_status_t status

status

struct spp_write_evt_param
#include <esp_spp_api.h>

ESP_SPP_WRITE_EVT.

Public Members

esp_spp_status_t status

status

uint32_t handle

The connection handle

int len

The length of the data written.

bool cong

congestion status

Structures

struct esp_spp_cfg_t

SPP configuration parameters.

Public Members

esp_spp_mode_t mode

Choose the mode of SPP, ESP_SPP_MODE_CB or ESP_SPP_MODE_VFS.

bool enable_l2cap_ertm

Enable/disable Logical Link Control and Adaptation Layer Protocol enhanced retransmission mode.

uint16_t tx_buffer_size

Tx buffer size for a new SPP channel. A smaller setting can save memory, but may incur a decrease in throughput. Only for ESP_SPP_MODE_VFS mode.

Macros

ESP_SPP_MAX_MTU

SPP max MTU

ESP_SPP_MAX_SCN

SPP max SCN

ESP_SPP_MIN_TX_BUFFER_SIZE

SPP min tx buffer

ESP_SPP_MAX_TX_BUFFER_SIZE

SPP max tx buffer size

BT_SPP_DEFAULT_CONFIG()

SPP default configuration.

ESP_SPP_SEC_NONE

No security. relate to BTA_SEC_NONE in bta/bta_api.h

ESP_SPP_SEC_AUTHORIZE

Authorization required (only needed for out going connection ) relate to BTA_SEC_AUTHORIZE in bta/bta_api.h

ESP_SPP_SEC_AUTHENTICATE

Authentication required. relate to BTA_SEC_AUTHENTICATE in bta/bta_api.h

ESP_SPP_SEC_ENCRYPT

Encryption required. relate to BTA_SEC_ENCRYPT in bta/bta_api.h

ESP_SPP_SEC_MODE4_LEVEL4

Mode 4 level 4 service, i.e. incoming/outgoing MITM and P-256 encryption relate to BTA_SEC_MODE4_LEVEL4 in bta/bta_api.h

ESP_SPP_SEC_MITM

Man-In-The_Middle protection relate to BTA_SEC_MITM in bta/bta_api.h

ESP_SPP_SEC_IN_16_DIGITS

Min 16 digit for pin code relate to BTA_SEC_IN_16_DIGITS in bta/bta_api.h

Type Definitions

typedef uint16_t esp_spp_sec_t
typedef void (*esp_spp_cb_t)(esp_spp_cb_event_t event, esp_spp_cb_param_t *param)

SPP callback function type. When handle ESP_SPP_DATA_IND_EVT, it is strongly recommended to cache incoming data, and process them in other lower priority application task rather than in this callback directly.

Param event

Event type

Param param

Point to callback parameter, currently is union type

Enumerations

enum esp_spp_status_t

Values:

enumerator ESP_SPP_SUCCESS

Successful operation.

enumerator ESP_SPP_FAILURE

Generic failure.

enumerator ESP_SPP_BUSY

Temporarily can not handle this request.

enumerator ESP_SPP_NO_DATA

No data

enumerator ESP_SPP_NO_RESOURCE

No more resource

enumerator ESP_SPP_NEED_INIT

SPP module shall init first

enumerator ESP_SPP_NEED_DEINIT

SPP module shall deinit first

enumerator ESP_SPP_NO_CONNECTION

Connection may have been closed

enumerator ESP_SPP_NO_SERVER

No SPP server

enum esp_spp_role_t

Values:

enumerator ESP_SPP_ROLE_MASTER

Role: master

enumerator ESP_SPP_ROLE_SLAVE

Role: slave

enum esp_spp_mode_t

Values:

enumerator ESP_SPP_MODE_CB

When data is coming, a callback will come with data

enumerator ESP_SPP_MODE_VFS

Use VFS to write/read data

enum esp_spp_cb_event_t

SPP callback function events.

Values:

enumerator ESP_SPP_INIT_EVT

When SPP is initialized, the event comes

enumerator ESP_SPP_UNINIT_EVT

When SPP is deinitialized, the event comes

enumerator ESP_SPP_DISCOVERY_COMP_EVT

When SDP discovery complete, the event comes

enumerator ESP_SPP_OPEN_EVT

When SPP Client connection open, the event comes

enumerator ESP_SPP_CLOSE_EVT

When SPP connection closed, the event comes

enumerator ESP_SPP_START_EVT

When SPP server started, the event comes

enumerator ESP_SPP_CL_INIT_EVT

When SPP client initiated a connection, the event comes

enumerator ESP_SPP_DATA_IND_EVT

When SPP connection received data, the event comes, only for ESP_SPP_MODE_CB

enumerator ESP_SPP_CONG_EVT

When SPP connection congestion status changed, the event comes, only for ESP_SPP_MODE_CB

enumerator ESP_SPP_WRITE_EVT

When SPP write operation completes, the event comes, only for ESP_SPP_MODE_CB

enumerator ESP_SPP_SRV_OPEN_EVT

When SPP Server connection open, the event comes

enumerator ESP_SPP_SRV_STOP_EVT

When SPP server stopped, the event comes

enumerator ESP_SPP_VFS_REGISTER_EVT

When SPP VFS register, the event comes

enumerator ESP_SPP_VFS_UNREGISTER_EVT

When SPP VFS unregister, the event comes

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