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esp-idf/examples/bluetooth/bluedroid/classic_bt/hfp_ag/README.md
weitianhua 78cbdfa332 HFP AG Example
2019-11-27 13:35:35 +00:00

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Hands-Free Audio Gateway

This example is to show how to use the APIs of Hands-Free (HF) Audio Gateway (AG) Component and the effects of them with the help of user commands. You can use this example to communicate with a Hands-Free Unit (e.g. a headphone set). This example uses UART as a transportation of user commands and configured GPIO for PCM audio data stream.

How to use example

Hardware Required

If possible, example should be able to run on any commonly available ESP32 development board and is supposed to connect to Hands Free Unit example (hfp_hf) in ESP-IDF.

Configure the project

idf.py menuconfig
  • Enable Classic Bluetooth, Hands Free/Handset and Aduio Gateway under Component config ---> Bluetooth ---> Bluedroid Options.
  • When using PCM as the data path and this example configures PCM audio data to GPIO pins. You can link the GPIO pins to a speaker via i2s port. PCM data path does not support mSBC codec but CVSD codec.
  • When using HCI data path, ESP32 support both CVSD and mSBC codec.

Build and Flash

Build the project and flash it to the board, then run monitor tool to view serial output:

idf.py -p PORT flash monitor

(Replace PORT with the name of the serial port to use.)

(To exit the serial monitor, type Ctrl-].)

See the Getting Started Guide for full steps to configure and use ESP-IDF to build projects.

Example Output

When you run this example the command table will prints like:

########################################################################
HFP AG command usage manual
HFP AG commands begins with "hf" and ends with ";"
Supported commands are as follows, arguments are embraced with < and >

hf con;                   -- setup connection with peer device
hf dis;                   -- release connection with peer device
hf cona;                  -- setup audio connection with peer device
hf disa;                  -- release connection with peer device
hf vron;                  -- start voice recognition
hf vroff;                 -- stop voice recognition
hf vu <tgt> <vol>;        -- volume update
     tgt: 0-speaker, 1-microphone
     vol: volume gain ranges from 0 to 15
hf ind <call> <ntk> <callsetup> <sig>;       -- unsolicited notify device notification to HF Client
     call: call status [0,1]
     callsetup: call setup status [0,3]
     ntk: network status [0,1]
     sig: signal strength value from 0~5
hf ate <rep> <err>;       -- send extended at error code
     rep: response code from 0 to 7
     err: error code from 0 to 32
hf iron;                  -- inband ring tone provided
hf iroff;                 -- inband ring tone not provided
hf ac;                    -- Answer Incoming Call from AG
hf rc;                    -- Reject Incoming Call from AG
hf d <num>;               -- Dial Number by AG, e.g. hf d 11223344
hf end;                   -- End up a call by AG
hf h;                     -- to see the command for HFP AG
########################################################################

The commands help table will print out in monitor whenever you type hf h; or input a command that is not required by the command parse rule.

Service Level Connection and Disconnection

You can type hf con; to establish a service level connection with HF Unit device and log prints like:

E (100147) CNSL: Command [hf dis;]
disconnect
W (100427) BT_RFCOMM: port_rfc_closed RFCOMM connection in state 3 closed: Closed (res: 19)
W (100427) BT_APPL: BTA_HF_CLIENT_SCO_SHUTDOWN_ST: Ignoring event 3
E (100427) BT_HF: APP HFP event: CONNECTION_STATE_EVT
E (100437) BT_HF: --connection state disconnected, peer feats 0x0, chld_feats 0x0

Note: Only after HF service is initiated and a service level connection exists between the HF Unit and AG that other commands are available.

You can type hf dis; to disconnect with the connected HF Unit device, and log prints like:

E (100147) CNSL: Command [hf dis;]
disconnect
W (100427) BT_RFCOMM: port_rfc_closed RFCOMM connection in state 3 closed: Closed (res: 19)
W (100427) BT_APPL: BTA_HF_CLIENT_SCO_SHUTDOWN_ST: Ignoring event 3
E (100427) BT_HF: APP HFP event: CONNECTION_STATE_EVT
E (100437) BT_HF: --connection state disconnected, peer feats 0x0, chld_feats 0x0

Audio Connection and Disconnection

You can type hf cona; to establish the audio connection between HF Unit and AG device. Also, you can type hf disa; to close the audio data stream.

Situations for Audio Connection

  • Answer an incoming call
  • Enable voice recognition
  • Dial an outgoing call

Situations for Audio Disconnection

  • Reject an incoming call
  • Disable the voice recognition

Audio Data path

ESP32 supports two type of audio data pth: PCM and HCI.

  • PCM : When using PCM audio data stream is "matrixed" to GPIO pins and you should link these GPIO pins to a speaker via i2s port.
  • HCI : When using HCI audio data stream will act in "loopback" mode. For example, you can hear your own voice when you place a call to a phone connected with a ESP32 development borad.

Codec

ESP32 supports both CVSD and mSBC codec. HF Unit and AG device determine which codec to use when establishing a service level connection. The choice of codec also depends on the user's configuration in menuconfig.

Since CVSD is the default codec in HFP, we just show the situation using mSBC :

  • If you enable BT_HFP_WBS_ENABLE in menuconfig, mSBC will be available.
  • If both HF Unit and AG support mSBC and also BT_HFP_WBS_ENABLE is enabled, ESP32 chooses mSBC.
  • If you use PCM data path, mSBC is not available.

Answer or Reject an Incoming Call

Answer an Incoming Call

You can type hf ac; to answer an incoming call and log prints like:

E (1066280) CNSL: Command [hf ac;]
Answer Call from AG.
W (1066280) BT_APPL: BTA_AG_SCO_CODEC_ST: Ignoring event 1
I (1067200) BT_APP_HF: APP HFP event: BCS_EVT
I (1067200) BT_APP_HF: --AG choose codec mode: CVSD Only
E (1067230) BT_BTM: btm_sco_connected, handle 180
I (1067240) BT_APP_HF: APP HFP event: AUDIO_STATE_EVT
I (1067240) BT_APP_HF: --Audio State connected

Reject an Incoming Call

You can type hf rc; to reject an incoming call and log prints like:

E (10040) CNSL: Command [hf rc;]
Reject Call from AG.
I (1067240) BT_APP_HF: APP HFP event: AUDIO_STATE_EVT
I (1067240) BT_APP_HF: --Audio State disconnected

End Up a Call

You can type hf end; to end up the current ongoing call and log prints like:

E (40390) CNSL: Command [hf end;]
End Call from AG.
I (1067240) BT_APP_HF: APP HFP event: AUDIO_STATE_EVT
I (1067240) BT_APP_HF: --Audio State disconnected

Dial Number

You can type hf d <num>; to dial <num> from AG and log prints like:

E (105600) CNSL: Command [hf d 18629485549;]
Dial number 18629485549
I (105610) BT_APP_HF: APP HFP event: AUDIO_STATE_EVT
I (105610) BT_APP_HF: --Audio State connecting
I (106120) BT_APP_HF: APP HFP event: BCS_EVT
I (106130) BT_APP_HF: --AG choose codec mode: CVSD Only
E (106160) BT_BTM: btm_sco_connected, handle 180
I (106160) BT_APP_HF: APP HFP event: AUDIO_STATE_EVT
I (106160) BT_APP_HF: --Audio State connected

Volume Control

You can type hf vu <tgt> <vol>; to sync volume gain of headset or microphone. The parameter set:

  • <tgt> : 0 - headset, 1 - microphone.
  • <vol> : Integer among 0 - 15.

For example, hf vu 0 9; sync the volume of headset and log on AG side prints volume update, on HF Unit side log prints like:

E (17087) BT_HF: APP HFP event: VOLUME_CONTROL_EVT
E (17087) BT_HF: --volume_target: SPEAKER, volume 9

And also, hf vu 1 9; sync the volume gain of microphone and log on HF Unit side prints like:

E (32087) BT_HF: APP HFP event: VOLUME_CONTROL_EVT
E (32087) BT_HF: --volume_target: MICROPHONE, volume 9

Voice Recognition

You can type hf vron; to start the voice recognition of AG and type hf vroff; to end the voice recognition. Both command will notify the HF Unit the status of voice recognition. For example, type hf vron; and log prints like:

E (203128) CNSL: Command [hf vron;]
Start Voice Recognition.
I (203138) BT_APP_HF: APP HFP event: AUDIO_STATE_EVT
I (203138) BT_APP_HF: --Audio State connecting
I (203148) BT_APP_HF: APP HFP event: AUDIO_STATE_EVT
I (1014138) BT_APP_HF: --Audio State connected

Notify Device Notification

When use hf ind <call> <ntk> <callsetup> <sig> AG will send some device status to HF Unit. Log on AG will printout like: Device Indicator Changed! and on HF Unit side will prints like:

E (293641) BT_HF: APP HFP event: CALL_IND_EVT
E (293641) BT_HF: --Call indicator call in progress
E (293641) BT_HF: APP HFP event: CALL_SETUP_IND_EVT
E (293651) BT_HF: --Call setup indicator INCOMING
E (293651) BT_HF: APP HFP event: SIGNAL_STRENGTH_IND_EVT
E (293661) BT_HF: -- signal strength: 5

Note: AG only sends changed status to HF Unit.

Send Extended AT Error Code

You can type hf ate <rep> <err> to send extended AT error coed to HF Unit. Parameter set:

  • <rep> : integer among 0 - 7.
  • <err> : integer among 0 - 32.

When you type hf ate 7 7; log on AG side prints like Send CME Error. and on HF Unit side prints like:

E (448146) BT_HF: APP HFP event: AT_RESPONSE
E (448146) BT_HF: --AT response event, code 7, cme 7

Inband Ring Tone Enable and Disable

You can type hf iron; to enable inband ring tone and type hf iroff; to disable inband ring tone. Log on AG side prints like Device Indicator Changed! and on HF Unit side prints like:

E (19546) BT_HF: APP HFP event: INBAND_RING_TONE_EVT
E (19556) BT_HF: --inband ring state Provided

Troubleshooting

  • You should type the command in the terminal according to the format described in the command help table.
  • Not all commands in the table are supported by HF Unit.
  • If you want to use AG to establish a service level connection with HF Unit, you should add the MAC address of HF Unit in hfp_hf/main/bt_app.c, for example: esp_bd_addr_t peer_addr = {0xb4, 0xe6, 0x2d, 0xeb, 0x09, 0x93};
  • Use esp_hf_client_register_callback() and esp_hf_client_init(); before establishing a service level connection.

Example Breakdown

This example has relatively more source files than other bluetooth examples because Hands Free Profile is somehow complex. But we want to show the functions of Hands Free Profile in a simple way, so we use the Commands and Effects scheme to show the usage of APIs of HFP in ESP-IDF.

  • The example will respond to user command through UART console. Please go to hfp_hf/main/console_uart.c for the configuration details.
  • For voice interface, ESP32 has provided PCM input/output signals which can be mapped to GPIO pins, please go to hfp_hf/main/gpio_pcm_config.c for the configuration details.
  • If you want to fix the command table, please refer to hfp_hf/main/app_hf_msg_set.c.
  • If you want to fix the command parse rules, please refer to hfp_hf/main/app_hf_msg_prs.c.
  • If you want to fix the responses of AG or want to fix the log, please refer to hfp_hf/main/bt_app_hf.c.
  • Task configuration part is in hfp_hf/main/bt_app_core.c.