HFP AG API

Application Examples

bluetooth/bluedroid/classic_bt/hfp_ag demonstrates how to use the Hands-Free Audio Gateway (HF-AG) component to communicate with a device that implements Hands-Free Client Role, such as a headphone set. It provides commands for configuring the project, establishing connections, controlling volume, and answering or rejecting calls.

API Reference

Header File

components/bt/host/bluedroid/api/include/api/esp_hf_ag_api.h
This header file can be included with:
#include "esp_hf_ag_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_hf_ag_register_callback(esp_hf_cb_t callback)

Register application callback function to HFP AG module. This function should be called only after esp_bluedroid_enable() completes successfully.

Parameters

callback -- [in] HFP AG event callback function

Returns

ESP_OK: success
ESP_ERR_INVALID_STATE: if bluetooth stack is not yet enabled
ESP_FAIL: if callback is a NULL function pointer

esp_err_t esp_hf_ag_init(void)

Initialize the bluetooth HF AG module. This function should be called after esp_bluedroid_enable() completes successfully.

Returns

ESP_OK: if the initialization request is sent successfully
ESP_ERR_INVALID_STATE: if bluetooth stack is not yet enabled
ESP_FAIL: others

esp_err_t esp_hf_ag_deinit(void)

De-initialize for HF AG module. This function should be called only after esp_bluedroid_enable() completes successfully.

Returns

ESP_OK: success
ESP_ERR_INVALID_STATE: if bluetooth stack is not yet enabled
ESP_FAIL: others

esp_err_t esp_hf_ag_slc_connect(esp_bd_addr_t remote_bda)

To establish a Service Level Connection to remote bluetooth HFP client device. This function must be called after esp_hf_ag_init() and before esp_hf_ag_deinit().

Parameters

remote_bda -- [in] remote bluetooth HFP client device address

Returns

ESP_OK: connect request is sent to lower layer
ESP_ERR_INVALID_STATE: if bluetooth stack is not yet enabled
ESP_FAIL: others

esp_err_t esp_hf_ag_slc_disconnect(esp_bd_addr_t remote_bda)

Disconnect from the remote HFP client. This function must be called after esp_hf_ag_init() and before esp_hf_ag_deinit().

Parameters

remote_bda -- [in] remote bluetooth device address

Returns

ESP_OK: disconnect request is sent to lower layer
ESP_ERR_INVALID_STATE: if bluetooth stack is not yet enabled
ESP_FAIL: others

esp_err_t esp_hf_ag_audio_connect(esp_bd_addr_t remote_bda)

Create audio connection with remote HFP client. As a precondition to use this API, Service Level Connection shall exist with HFP client.

Parameters

remote_bda -- [in] remote bluetooth device address

Returns

ESP_OK: audio connect request is sent to lower layer
ESP_ERR_INVALID_STATE: if bluetooth stack is not yet enabled
ESP_FAIL: others

esp_err_t esp_hf_ag_audio_disconnect(esp_bd_addr_t remote_bda)

Release the established audio connection with remote HFP client. As a precondition to use this API, Service Level Connection shall exist with HFP client.

Parameters

remote_bda -- [in] remote bluetooth device address

Returns

ESP_OK: audio disconnect request is sent to lower layer
ESP_ERR_INVALID_STATE: if bluetooth stack is not yet enabled
ESP_FAIL: others

esp_err_t esp_hf_ag_vra_control(esp_bd_addr_t remote_bda, esp_hf_vr_state_t value)

Response of Volume Recognition Command(AT+VRA) from HFP client. As a precondition to use this API, Service Level Connection shall exist with HFP client.

Parameters

remote_bda -- [in] the device address of voice recognition initiator
value -- [in] 0 - voice recognition disabled, 1- voice recognition enabled

Returns

ESP_OK: response of volume recognition is sent to lower layer
ESP_ERR_INVALID_STATE: if bluetooth stack is not yet enabled
ESP_FAIL: others

esp_err_t esp_hf_ag_volume_control(esp_bd_addr_t remote_bda, esp_hf_volume_control_target_t type, int volume)

Volume synchronization with HFP client. As a precondition to use this API, Service Level Connection shall exist with HFP client.

Parameters

remote_bda -- [in] remote bluetooth device address
type -- [in] volume control target, speaker or microphone
volume -- [in] gain of the speaker of microphone, ranges 0 to 15

Returns

ESP_OK: volume synchronization control is sent to lower layer
ESP_ERR_INVALID_STATE: if bluetooth stack is not yet enabled
ESP_ERR_INVALID_ARG: if arguments are invalid
ESP_FAIL: others

esp_err_t esp_hf_ag_unknown_at_send(esp_bd_addr_t remote_addr, char *unat)

Handle Unknown AT command from HFP Client. As a precondition to use this API, Service Level Connection shall exist with HFP client.

Parameters

remote_addr -- [in] remote bluetooth device address
unat -- [in] User AT command response to HF Client. It will response "ERROR" by default if unat is NULL.

Returns

ESP_OK: response of unknown AT command is sent to lower layer
ESP_ERR_INVALID_STATE: if bluetooth stack is not yet enabled
ESP_FAIL: others

esp_err_t esp_hf_ag_cmee_send(esp_bd_addr_t remote_bda, esp_hf_at_response_code_t response_code, esp_hf_cme_err_t error_code)

Unsolicited send extend AT error code to HFP Client. As a precondition to use this API, Service Level Connection shall exist with HFP client.

Parameters

remote_bda -- [in] remote bluetooth device address
response_code -- [in] AT command response code
error_code -- [in] CME error code

Returns

ESP_OK: extend error code is sent to lower layer
ESP_ERR_INVALID_STATE: if bluetooth stack is not yet enabled
ESP_FAIL: others

esp_err_t esp_hf_ag_devices_status_indchange(esp_bd_addr_t remote_addr, esp_hf_call_status_t call_state, esp_hf_call_setup_status_t call_setup_state, esp_hf_network_state_t ntk_state, int signal)

Unsolicited send device status notification to HFP Client. As a precondition to use this API, Service Level Connection shall exist with HFP client.

Parameters

remote_addr -- [in] remote bluetooth device address
call_state -- [in] call state
call_setup_state -- [in] call setup state
ntk_state -- [in] network service state
signal -- [in] signal strength from 0 to 5

Returns

ESP_OK: device status notification is sent to lower layer
ESP_ERR_INVALID_STATE: if bluetooth stack is not yet enabled
ESP_ERR_INVALID_ARG: if arguments are invalid
ESP_FAIL: others

esp_err_t esp_hf_ag_ciev_report(esp_bd_addr_t remote_addr, esp_hf_ciev_report_type_t ind_type, int value)

Send indicator report "+CIEV: <ind> <value>" to HFP Client. "CIEV" means “indicator events reporting", and all indicator types can be sent one type at a time. As a precondition to use this API, Service Level Connection shall exist with HFP client.

Parameters

remote_addr -- [in] remote bluetooth device address
ind_type -- [in] indicator type
value -- [in] indicator value

Returns

ESP_OK: indicator report is sent to lower layer
ESP_ERR_INVALID_STATE: if bluetooth stack is not yet enabled
ESP_FAIL: others

esp_err_t esp_hf_ag_cind_response(esp_bd_addr_t remote_addr, esp_hf_call_status_t call_state, esp_hf_call_setup_status_t call_setup_state, esp_hf_network_state_t ntk_state, int signal, esp_hf_roaming_status_t roam, int batt_lev, esp_hf_call_held_status_t call_held_status)

Response to device individual indicators to HFP Client. As a precondition to use this API, Service Level Connection shall exist with HFP client.

Parameters

remote_addr -- [in] remote bluetooth device address
call_state -- [in] call state
call_setup_state -- [in] call setup state
ntk_state -- [in] network service state
signal -- [in] signal strength from 0 to 5
roam -- [in] roam state
batt_lev -- [in] battery level from 0 to 5
call_held_status -- [in] call held status

Returns

ESP_OK: response to device individual indicators is sent to lower layer
ESP_ERR_INVALID_STATE: if bluetooth stack is not yet enabled
ESP_ERR_INVALID_ARG: if the arguments are invalid
ESP_FAIL: others

esp_err_t esp_hf_ag_cops_response(esp_bd_addr_t remote_addr, char *name)

Reponse for AT+COPS command from HF Client. As a precondition to use this API, Service Level Connection shall exist with HFP client.

Parameters

remote_addr -- [in] remote bluetooth device address
name -- [in] current operator name

Returns

ESP_OK: reponse for AT+COPS command is sent to lower layer
ESP_ERR_INVALID_STATE: if bluetooth stack is not yet enabled
ESP_FAIL: others

esp_err_t esp_hf_ag_clcc_response(esp_bd_addr_t remote_addr, int index, esp_hf_current_call_direction_t dir, esp_hf_current_call_status_t current_call_state, esp_hf_current_call_mode_t mode, esp_hf_current_call_mpty_type_t mpty, char *number, esp_hf_call_addr_type_t type)

Response to AT+CLCC command from HFP Client. As a precondition to use this API, Service Level Connection shall exist with HFP client.

Parameters

remote_addr -- [in] remote bluetooth device address
index -- [in] the index of current call, starting with 1, finishing response with 0 (send OK)
dir -- [in] call direction (incoming/outgoing)
current_call_state -- [in] current call state
mode -- [in] current call mode (voice/data/fax)
mpty -- [in] single or multi type
number -- [in] current call number
type -- [in] international type or unknow

Returns

ESP_OK: response to AT+CLCC command is sent to lower layer
ESP_ERR_INVALID_STATE: if bluetooth stack is not yet enabled
ESP_FAIL: others

esp_err_t esp_hf_ag_cnum_response(esp_bd_addr_t remote_addr, char *number, int number_type, esp_hf_subscriber_service_type_t service_type)

Response for AT+CNUM command from HF Client. As a precondition to use this API, Service Level Connection shall exist with HFP client.

Parameters

remote_addr -- [in] remote bluetooth device address
number -- [in] registration number
number_type -- [in] value of number type from 128-143: national or international, may contain prefix and/or escape digits 144-159: international, includes country code prefix, add "+" if needed 160-175: national, but no prefix nor escape digits
service_type -- [in] service type (unknown/voice/fax)

Returns

ESP_OK: response for AT+CNUM command is sent to lower layer
ESP_ERR_INVALID_STATE: if bluetooth stack is not yet enabled
ESP_FAIL: others

esp_err_t esp_hf_ag_bsir(esp_bd_addr_t remote_addr, esp_hf_in_band_ring_state_t state)

Inform HF Client that AG Provided in-band ring tone or not. As a precondition to use this API, Service Level Connection shall exist with HFP client.

Parameters

remote_addr -- [in] remote bluetooth device address
state -- [in] in-band ring tone state

Returns

ESP_OK: information of in-band ring tone is sent to lower layer
ESP_ERR_INVALID_STATE: if bluetooth stack is not yet enabled
ESP_ERR_INVALID_ARG: if arguments are invalid
ESP_FAIL: others

esp_err_t esp_hf_ag_answer_call(esp_bd_addr_t remote_addr, int num_active, int num_held, esp_hf_call_status_t call_state, esp_hf_call_setup_status_t call_setup_state, char *number, esp_hf_call_addr_type_t call_addr_type)

Answer Incoming Call from AG. As a precondition to use this API, Service Level Connection shall exist with HFP client.

Parameters

remote_addr -- [in] remote bluetooth device address
num_active -- [in] the number of active call
num_held -- [in] the number of held call
call_state -- [in] call state
call_setup_state -- [in] call setup state
number -- [in] number of the incoming call
call_addr_type -- [in] call address type

Returns

ESP_OK: answer incoming call is sent to lower layer
ESP_ERR_INVALID_STATE: if bluetooth stack is not yet enabled
ESP_FAIL: others

esp_err_t esp_hf_ag_reject_call(esp_bd_addr_t remote_addr, int num_active, int num_held, esp_hf_call_status_t call_state, esp_hf_call_setup_status_t call_setup_state, char *number, esp_hf_call_addr_type_t call_addr_type)

Reject Incoming Call from AG. As a precondition to use this API, Service Level Connection shall exist with HFP client.

Parameters

remote_addr -- [in] remote bluetooth device address
num_active -- [in] the number of active call
num_held -- [in] the number of held call
call_state -- [in] call state
call_setup_state -- [in] call setup state
number -- [in] number of the incoming call
call_addr_type -- [in] call address type

Returns

ESP_OK: reject incoming call is sent to lower layer
ESP_ERR_INVALID_STATE: if bluetooth stack is not yet enabled
ESP_FAIL: others

esp_err_t esp_hf_ag_out_call(esp_bd_addr_t remote_addr, int num_active, int num_held, esp_hf_call_status_t call_state, esp_hf_call_setup_status_t call_setup_state, char *number, esp_hf_call_addr_type_t call_addr_type)

Initiate a call from AG. As a precondition to use this API, Service Level Connection shall exist with HFP client. If the AG is driven by the HF to call esp_hf_ag_out_call, it needs to response an OK or ERROR to HF. But if the AG is actively calling esp_hf_ag_out_call, it does not need to take a response to HF.

Parameters

remote_addr -- [in] remote bluetooth device address
num_active -- [in] the number of active call
num_held -- [in] the number of held call
call_state -- [in] call state
call_setup_state -- [in] call setup state
number -- [in] number of the outgoing call
call_addr_type -- [in] call address type

Returns

ESP_OK: a call initiation is sent to lower layer
ESP_ERR_INVALID_STATE: if bluetooth stack is not yet enabled
ESP_FAIL: others

esp_err_t esp_hf_ag_end_call(esp_bd_addr_t remote_addr, int num_active, int num_held, esp_hf_call_status_t call_state, esp_hf_call_setup_status_t call_setup_state, char *number, esp_hf_call_addr_type_t call_addr_type)

End an ongoing call. As a precondition to use this API, Service Level Connection shall exist with HFP client.

Parameters

remote_addr -- [in] remote bluetooth device address
num_active -- [in] the number of active call
num_held -- [in] the number of held call
call_state -- [in] call state
call_setup_state -- [in] call setup state
number -- [in] number of the call
call_addr_type -- [in] call address type

Returns

ESP_OK: end an ongoing call is sent to lower layer
ESP_ERR_INVALID_STATE: if bluetooth stack is not yet enabled
ESP_FAIL: others

esp_err_t esp_hf_ag_register_data_callback(esp_hf_incoming_data_cb_t recv, esp_hf_outgoing_data_cb_t send)

Register AG data output function. The callback is only used in the case that Voice Over HCI is enabled.

Parameters

recv -- [in] HFP client incoming data callback function
send -- [in] HFP client outgoing data callback function

Returns

ESP_OK: success
ESP_ERR_INVALID_STATE: if bluetooth stack is not yet enabled
ESP_FAIL: if callback is a NULL function pointer

esp_err_t esp_hf_ag_pkt_stat_nums_get(uint16_t sync_conn_handle)

Get the number of packets received and sent.

             This function is only used in the case that Voice Over HCI is enabled and the audio state is connected.
             When the operation is completed, the callback function will be called with ESP_HF_PKT_STAT_NUMS_GET_EVT.

Parameters

sync_conn_handle -- [in] the (e)SCO connection handle

Returns

ESP_OK: if the request is sent successfully
ESP_ERR_INVALID_STATE: if bluetooth stack is not yet enabled
ESP_FAIL: others

void esp_hf_ag_outgoing_data_ready(void)

Trigger the lower-layer to fetch and send audio data.

             This function is only used in the case that Voice Over HCI is enabled.
             As a precondition to use this API, Service Level Connection shall exist with HFP client.
             After this function is called, lower layer will invoke esp_hf_client_outgoing_data_cb_t to fetch data

Unions

union esp_hf_cb_param_t

#include <esp_hf_ag_api.h>

HFP AG callback parameters.

Public Members

struct esp_hf_cb_param_t::hf_conn_stat_param conn_stat: AG callback param of ESP_HF_CONNECTION_STATE_EVT

struct esp_hf_cb_param_t::hf_audio_stat_param audio_stat: AG callback param of ESP_HF_AUDIO_STATE_EVT

struct esp_hf_cb_param_t::hf_vra_rep_param vra_rep: AG callback param of ESP_HF_BVRA_RESPONSE_EVT

struct esp_hf_cb_param_t::hf_volume_control_param volume_control: AG callback param of ESP_HF_VOLUME_CONTROL_EVT

struct esp_hf_cb_param_t::hf_unat_rep_param unat_rep: AG callback param of ESP_HF_UNAT_RESPONSE_EVT

struct esp_hf_cb_param_t::hf_out_call_param out_call: AG callback param of ESP_HF_DIAL_EVT

struct esp_hf_cb_param_t::hf_ind_upd_param ind_upd: AG callback param of ESP_HF_IND_UPDATE_EVT

struct esp_hf_cb_param_t::hf_cind_rep_param cind_rep: AG callback param of ESP_HF_CIND_RESPONSE_EVT

struct esp_hf_cb_param_t::hf_cops_rep_param cops_rep: AG callback param of ESP_HF_COPS_RESPONSE_EVT

struct esp_hf_cb_param_t::hf_clcc_rep_param clcc_rep: AG callback param of ESP_HF_CLCC_RESPONSE_EVT

struct esp_hf_cb_param_t::hf_cnum_rep_param cnum_rep: AG callback param of ESP_HF_CNUM_RESPONSE_EVT

struct esp_hf_cb_param_t::hf_vts_rep_param vts_rep: AG callback param of ESP_HF_VTS_RESPONSE_EVT

struct esp_hf_cb_param_t::hf_nrec_param nrec: AG callback param of ESP_HF_NREC_RESPONSE_EVT

struct esp_hf_cb_param_t::hf_ata_rep_param ata_rep: AG callback param of ESP_HF_ATA_RESPONSE_EVT

struct esp_hf_cb_param_t::hf_chup_rep_param chup_rep: AG callback param of ESP_HF_CHUP_RESPONSE_EVT

struct esp_hf_cb_param_t::hf_wbs_rep_param wbs_rep: AG callback param of ESP_HF_WBS_RESPONSE_EVT

struct esp_hf_cb_param_t::hf_bcs_rep_param bcs_rep: AG callback param of ESP_HF_BCS_RESPONSE_EVT

struct esp_hf_cb_param_t::ag_pkt_status_nums pkt_nums: AG callback param of ESP_HF_PKT_STAT_NUMS_GET_EVT

struct ag_pkt_status_nums

#include <esp_hf_ag_api.h>

ESP_HF_PKT_STAT_NUMS_GET_EVT.

Public Members

uint32_t rx_total: the total number of packets received

uint32_t rx_correct: the total number of packets data correctly received

uint32_t rx_err: the total number of packets data with possible invalid

uint32_t rx_none: the total number of packets data no received

uint32_t rx_lost: the total number of packets data partially lost

uint32_t tx_total: the total number of packets send

uint32_t tx_discarded: the total number of packets send lost

struct hf_ata_rep_param

#include <esp_hf_ag_api.h>

ESP_HF_ATA_RESPONSE_EVT.

Public Members

esp_bd_addr_t remote_addr: remote bluetooth device address

struct hf_audio_stat_param

#include <esp_hf_ag_api.h>

ESP_HF_AUDIO_STATE_EVT.

Public Members

esp_bd_addr_t remote_addr: Remote bluetooth device address

esp_hf_audio_state_t state: Audio connection state

uint16_t sync_conn_handle: (e)SCO connection handle

struct hf_bcs_rep_param

#include <esp_hf_ag_api.h>

ESP_HF_BCS_RESPONSE_EVT.

Public Members

esp_bd_addr_t remote_addr: Remote bluetooth device address

esp_hf_wbs_config_t mode: codec mode CVSD or mSBC

struct hf_chup_rep_param

#include <esp_hf_ag_api.h>

ESP_HF_CHUP_RESPONSE_EVT.

Public Members

esp_bd_addr_t remote_addr: remote bluetooth device address

struct hf_cind_rep_param

#include <esp_hf_ag_api.h>

ESP_HF_CIND_RESPONSE_EVT.

Public Members

esp_bd_addr_t remote_addr: remote bluetooth device address

struct hf_clcc_rep_param

#include <esp_hf_ag_api.h>

ESP_HF_CLCC_RESPONSE_EVT.

Public Members

esp_bd_addr_t remote_addr: remote bluetooth device address

struct hf_cnum_rep_param

#include <esp_hf_ag_api.h>

ESP_HF_CNUM_RESPONSE_EVT.

Public Members

esp_bd_addr_t remote_addr: remote bluetooth device address

struct hf_conn_stat_param

#include <esp_hf_ag_api.h>

ESP_HF_CONNECTION_STATE_EVT.

Public Members

esp_bd_addr_t remote_bda: Remote bluetooth device address

esp_hf_connection_state_t state: Connection state

uint32_t peer_feat: HF supported features

uint32_t chld_feat: AG supported features on call hold and multiparty services

struct hf_cops_rep_param

#include <esp_hf_ag_api.h>

ESP_HF_COPS_RESPONSE_EVT.

Public Members

esp_bd_addr_t remote_addr: remote bluetooth device address

struct hf_ind_upd_param

#include <esp_hf_ag_api.h>

ESP_HF_IND_UPDATE_EVT.

Public Members

esp_bd_addr_t remote_addr: remote bluetooth device address

struct hf_nrec_param

#include <esp_hf_ag_api.h>

ESP_HF_NREC_RESPONSE_EVT.

Public Members

esp_bd_addr_t remote_addr: Remote bluetooth device address

esp_hf_nrec_t state: NREC enabled or disabled

struct hf_out_call_param

#include <esp_hf_ag_api.h>

ESP_HF_DIAL_EVT.

Public Members

esp_bd_addr_t remote_addr: remote bluetooth device address

esp_hf_dial_type_t type: dial type

char *num_or_loc: location in phone memory

struct hf_unat_rep_param

#include <esp_hf_ag_api.h>

ESP_HF_UNAT_RESPONSE_EVT.

Public Members

esp_bd_addr_t remote_addr: Remote bluetooth device address

char *unat: Unknown AT command string

struct hf_volume_control_param

#include <esp_hf_ag_api.h>

ESP_HF_VOLUME_CONTROL_EVT.

Public Members

esp_bd_addr_t remote_addr: Remote bluetooth device address

esp_hf_volume_type_t type: Volume control target, speaker or microphone

int volume: Gain, ranges from 0 to 15

struct hf_vra_rep_param

#include <esp_hf_ag_api.h>

ESP_HF_BVRA_RESPONSE_EVT.

Public Members

esp_bd_addr_t remote_addr: Remote bluetooth device address

esp_hf_vr_state_t value: Voice recognition state

struct hf_vts_rep_param

#include <esp_hf_ag_api.h>

ESP_HF_VTS_RESPONSE_EVT.

Public Members

esp_bd_addr_t remote_addr: Remote bluetooth device address

char *code: MTF code from HF Client

struct hf_wbs_rep_param

#include <esp_hf_ag_api.h>

ESP_HF_WBS_RESPONSE_EVT.

Public Members

esp_bd_addr_t remote_addr: Remote bluetooth device address

esp_hf_wbs_config_t codec: codec mode CVSD or mSBC

Macros

ESP_HF_PEER_FEAT_3WAY

ESP_HF_PEER_FEAT_ECNR

ESP_HF_PEER_FEAT_VREC

ESP_HF_PEER_FEAT_INBAND

ESP_HF_PEER_FEAT_VTAG

ESP_HF_PEER_FEAT_REJECT

ESP_HF_PEER_FEAT_ECS

ESP_HF_PEER_FEAT_ECC

ESP_HF_PEER_FEAT_EXTERR

ESP_HF_PEER_FEAT_CODEC

ESP_HF_PEER_FEAT_HF_IND

ESP_HF_PEER_FEAT_ESCO_S4

ESP_HF_CHLD_FEAT_REL

ESP_HF_CHLD_FEAT_REL_ACC

ESP_HF_CHLD_FEAT_REL_X

ESP_HF_CHLD_FEAT_HOLD_ACC

ESP_HF_CHLD_FEAT_PRIV_X

ESP_HF_CHLD_FEAT_MERGE

ESP_HF_CHLD_FEAT_MERGE_DETACH

Type Definitions

typedef void (*esp_hf_incoming_data_cb_t)(const uint8_t *buf, uint32_t len)

AG incoming data callback function, the callback is useful in case of Voice Over HCI.

Param buf: [in] : pointer to incoming data(payload of HCI synchronous data packet), the buffer is allocated inside bluetooth protocol stack and will be released after invoke of the callback is finished.
Param len: [in] : size(in bytes) in buf

typedef uint32_t (*esp_hf_outgoing_data_cb_t)(uint8_t *buf, uint32_t len)

AG outgoing data callback function, the callback is useful in case of Voice Over HCI. Once audio connection is set up and the application layer has prepared data to send, the lower layer will call this function to read data and then send. This callback is supposed to be implemented as non-blocking, and if data is not enough, return value 0 is supposed.

Param buf: [in] : pointer to incoming data(payload of HCI synchronous data packet), the buffer is allocated inside bluetooth protocol stack and will be released after invoke of the callback is finished.
Param len: [in] : size(in bytes) in buf
Return: length of data successfully read

typedef void (*esp_hf_cb_t)(esp_hf_cb_event_t event, esp_hf_cb_param_t *param)

HF AG callback function type.

Param event: : Event type
Param param: : Pointer to callback parameter

Enumerations

enum esp_hf_cb_event_t

HF callback events.

Values:

enumerator ESP_HF_CONNECTION_STATE_EVT: Connection state changed event

enumerator ESP_HF_AUDIO_STATE_EVT: Audio connection state change event

enumerator ESP_HF_BVRA_RESPONSE_EVT: Voice recognition state change event

enumerator ESP_HF_VOLUME_CONTROL_EVT: Audio volume control command from HF Client, provided by +VGM or +VGS message

enumerator ESP_HF_UNAT_RESPONSE_EVT: Unknown AT cmd Response

enumerator ESP_HF_IND_UPDATE_EVT: Indicator Update Event

enumerator ESP_HF_CIND_RESPONSE_EVT: Call And Device Indicator Response

enumerator ESP_HF_COPS_RESPONSE_EVT: Current operator information

enumerator ESP_HF_CLCC_RESPONSE_EVT: List of current calls notification

enumerator ESP_HF_CNUM_RESPONSE_EVT: Subscriber information response from HF Client

enumerator ESP_HF_VTS_RESPONSE_EVT: Enable or not DTMF

enumerator ESP_HF_NREC_RESPONSE_EVT: Enable or not NREC

enumerator ESP_HF_ATA_RESPONSE_EVT: Answer an Incoming Call

enumerator ESP_HF_CHUP_RESPONSE_EVT: Reject an Incoming Call

enumerator ESP_HF_DIAL_EVT: Origin an outgoing call with specific number or the dial the last number

enumerator ESP_HF_WBS_RESPONSE_EVT: Codec Status

enumerator ESP_HF_BCS_RESPONSE_EVT: Final Codec Choice

enumerator ESP_HF_PKT_STAT_NUMS_GET_EVT: Request number of packet different status

enum esp_hf_dial_type_t

Dial type of ESP_HF_DIAL_EVT.

Values:

enumerator ESP_HF_DIAL_NUM: Dial with a phone number

enumerator ESP_HF_DIAL_VOIP: Dial with VoIP

enumerator ESP_HF_DIAL_MEM: Dial with a memory position

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