Esp32 (6): Bluetooth and WiFi functions for function development

    Bluetooth and WIFI yes ESP32 Core functions , Bluetooth and wifi The coexistence of esp32 Your unique martial arts , However, it will be found later that there will be many problems in coexistence . No matter what , Bluetooth and wifi stay esp-idf There are many examples in , You can refer to . This article only gives a brief introduction to the process .

    

    1、 bluetooth a2dp sink The initialization

     blue ⽛ Tooth is ⼀ A short-range communication system , Its key characteristics include robustness 、 low power consumption 、 Low cost, etc . blue ⽛ The system is divided into two parts Kind of no 不 Same technology ： Classic Bluetooth (Classic Bluetooth) He LAN ⽛ Low power consumption (Bluetooth Low Energy).ESP32 Support dual mode blue ⽛, At the same time ⽀ Support classic blue ⽛ And Bluetooth low power consumption .

    Our project Bluetooth only uses A2DP, Basically from esp-idf/examples/bluetooth/a2dp_sink The sample code is modified from , Most have not been changed ,

    esp_bt_controller_config_t bt_cfg = BT_CONTROLLER_INIT_CONFIG_DEFAULT();

    if (esp_bt_controller_init(&bt_cfg) != ESP_OK) {

        ESP_LOGE(BT_AV_TAG, "%s initialize controller failed\n", __func__);

        return;

    }

    if (esp_bt_controller_enable(ESP_BT_MODE_BTDM) != ESP_OK) {

        ESP_LOGE(BT_AV_TAG, "%s enable controller failed\n", __func__);

        return;

    }

    if (esp_bluedroid_init() != ESP_OK) {

        ESP_LOGE(BT_AV_TAG, "%s initialize bluedroid failed\n", __func__);

        return;

    }

    if (esp_bluedroid_enable() != ESP_OK) {

        ESP_LOGE(BT_AV_TAG, "%s enable bluedroid failed\n", __func__);

        return;

    }

    /* create application task */

    bt_app_task_start_up();

    /* Bluetooth device name, connection mode and profile set up */

    bt_app_work_dispatch(bt_av_hdl_stack_evt, BT_APP_EVT_STACK_UP, NULL, 0, NULL);

    Our device is similar to the function of Bluetooth speakers , In the use of a2dp There are also many in the process of bug Of , For example, the noise after pause 、 Bluetooth sound jam 、 System panic etc. , I hope the following esp-idf It's all settled , If you encounter similar problems , We can also discuss in the blog , I won't go into details here .

2、Wifi The initialization

    Wifi Initialization of is relatively simple , Called API as follows , Follow up Wifi Status is handled with callbacks .

    esp-idf Example ： esp-idf/examples/wifi/simple_wifi

    void initialise_wifi()

    {

        tcpip_adapter_init();

        global_wifi_event_group = xEventGroupCreate();

        ESP_ERROR_CHECK( esp_event_loop_init(event_handler, NULL) );

        wifi_init_config_t cfg = WIFI_INIT_CONFIG_DEFAULT();

        ESP_ERROR_CHECK( esp_wifi_init(&cfg) );

        ESP_ERROR_CHECK( esp_wifi_set_mode(WIFI_MODE_STA) );

        ESP_ERROR_CHECK( esp_wifi_start() );

        status.wifi_init_done = true;

    }

    

    ESP32 Supported by the Wifi The pattern of is still very rich ：

    Station Pattern 、AP Pattern 、Station and AP Coexistence mode 、 Hybrid mode （ For monitoring Wifi package ）、

    3、WIFI Configuration of

    IOT Devices usually have no interface interaction , So when he acts as station When , They all face a problem ,Wifi The connected AP Of ssid And how to configure the password ？

    ESP I have thought of it for us , And provides a centralized way ：

    1)、SmartConfig

    SmartConfig  You need one on your mobile phone APP To match , mobile phone APP Come and broadcast AP Of SSID and PASSWORD,ESP32 To monitor the transmission of specific packets on the air interface , And from these packages, we can parse SSID and PASSWORD.

    The logic of the upper layer is roughly like this , The underlying protocol is not scrutinized , It should be that 802.11 Some mechanisms to extend .

    The configuration of our project is SmartConfig, So far, the effect is pretty good , The success rate is very high .

    2)、ESP NOW

    ESP NOW It is defined by Lexin as connectionless WIFI Communication protocol , The data is encapsulated in vendor-specific To transmit . For more information, please refer to the documentation .

    3)、 Custom scheme

    If you support Bluetooth , It can also be configured via Bluetooth WIFI;

    The device can also default to AP Pattern , Configure after the client is connected WIFI Then switch to STATION Pattern ;

    Both schemes need more development .