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History

zhiweijian b9a1756202 fix(ble/bluedroid): Remove BLE functions discard declaration fix(nt/bluedroid): Split the device name set functions feat(bt/bluedroid): added APIs to get/set device name on BT GAP side change(bt/common): Marked some APIs in device module as deprecated 1. esp_bt_dev_set_device_name 2. esp_bt_dev_get_device_name change(bt/bluedroid): use BT GAP APIs to set/get device name in bluetooth classic examples change(bt/bluedroid): use BT/BLE GAP APIs to set/get device name in coexist examples		2024-04-18 15:53:54 +08:00
..
main	fix(ble/bluedroid): Remove BLE functions discard declaration	2024-04-18 15:53:54 +08:00
CMakeLists.txt	tools: Increase the minimal supported CMake version to 3.16	2022-06-01 06:35:02 +00:00
README.md	docs(examples/bluetooth): Add the sequence diagram of L2CAP connection and the discription for the sequence diagram	2023-07-07 20:12:05 +08:00
sdkconfig.defaults	add l2cap server demo	2022-05-28 23:34:21 +00:00

README.md

Supported Targets	ESP32

ESP-IDF BT-L2CAP-SERVER EXAMPLE

This example is to show how to use the APIs of Logical Link Control and Adaptation Layer Protocol (L2CAP) to create an L2CAP server. We also provide demo bt_l2cap_client to create L2CAP client. In fact, you can create L2CAP clients and L2CAP servers on a single device at the same time.

How to use example

Hardware Required

This example is designed to run on commonly available ESP32 development board, e.g. ESP32-DevKitC. To operate the example, it should be connected to the L2CAP client running on another ESP32 board.

Configure the project

Open the project configuration menu:

idf.py menuconfig

Enable the BT-L2CAP functionality by choosing the path as following:

Component config --> Bluetooth --> Bluedroid Options --> BT-L2CAP

If you want to limit the number of connected devices, please make sure set the BT/BLE MAX ACL CONNECTIONS and BR/EDR ACL Max Connections with same value you want.

Component config --> Bluetooth --> Bluedroid Options --> BT/BLE MAX ACL CONNECTIONS(1~7) and Component config --> Bluetooth --> Bluetooth --> Bluetooth controller --> BR/EDR ACL Max Connections

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

After the program is started, the example starts inquiry scan and page scan, awaiting being discovered and connected. Other bluetooth devices can discover a device named "ESP_BT_L2CAP_SERVER". ESP-IDF examples for other L2CAP client can be used to connect to the local device.

When you run this example, the explain prints the following at the very begining:

I (1398) L2CAP_TAG: ESP_BT_L2CAP_INIT_EVT: status:0

I (1398) L2CAP_TAG: ESP_BT_L2CAP_START_EVT: status:0, hdl:0x0, sec_id:0x37

I (1408) SDP_TAG: ESP_SDP_INIT_EVT: status:0

I (1408) SDP_TAG: ESP_SDP_CREATE_RECORD_COMP_EVT: status:0

I (1418) L2CAP_TAG: event: 10
I (1428) L2CAP_TAG: Own address:[c4:dd:57:5b:e7:46]

Troubleshooting

This example just demonstrates how to use the SDP and L2CAP APIs. This example cannot establish an l2cap connection with other devices (smartphones, computers, etc.) because the UUID is unknown and does not conform to the Bluetooth protocol standard.
You can complete OBEX related profiles through SPP, SDP and L2CAP APIs.

Workflow of an L2CAP Connection

This example_workflow file describes the workflow of an L2CAP connection.