ESP32-C3入门教程 WiFi篇③——WiFi SoftAP 模式开启AP热点

「爱情、让人受尽委屈。」 2022-09-13 00:24 2055阅读 0赞

### 文章目录 ###

*  一、前言
 *  二、WiFi模式
 *  三、快速运行
 *  四、运行效果
 *  五、程序流程
 *   *  5.1 主程序
     *  5.2 注册事件回调函数
 *  六、关键函数
 *   *  6.1 将事件回调函数注册到特定循环
     *  6.2 设置 ESP32 STA 或 AP 的配置

# 一、前言 #

> 本文基于VS Code IDE进行编程、编译、下载、运行等操作  
> 基础知识点请查阅：[ESP32-C3入门教程 基础篇①——基于VS Code构建Hello World][ESP32-C3_ _VS Code_Hello World]

# 二、WiFi模式 #

ESP32给WiFi提供了三种模式

*  基站模式（即 STA 模式或 Wi-Fi 客户端模式），此时 ESP32-C3 连接到接入点 (AP)。
 *  AP 模式（即 Soft-AP 模式或接入点模式），此时其他WiFi设备连接到 ESP32-C3。
 *  AP-STA 共存模式（ESP32-C3 既是接入点，同时又作为基站连接到另外一个接入点）。

本博文描述ESP32-C3作为Soft-AP 模式，开启WiFi AP热点，供其他WiFi设备连接。

# 三、快速运行 #

*  示例项目中，选择`WiFi`—>`getting_started`\->`softAP`
 *  `menuconfig`配置`ESP32C3-Specific`—>`Rec 0`
 *  芯片选择`ESP32-C3(Built-in USB JTAG)`
 *  快速运行`ESP-IDF Build, Flash and Monitor`（左下角）

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# 四、运行效果 #

*  修改WiFi AP的SSID和password
 *  使用手机连接该AP
 *  使用手机断开该AP

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# 五、程序流程 #

## 5.1 主程序 ##

*  `nvs_flash_init`，初始化默认 NVS 分区。
 *  `esp_netif_init`，初始化底层TCP/IP堆栈
 *  `esp_event_loop_create_default`，创建默认事件循环。
 *  `esp_netif_create_default_wifi_ap`，使用默认WiFi AP配置创建`esp_netif`对象，将netif连接到WiFi并注册默认WiFi处理程序。
 *  `esp_wifi_init`，为 WiFi 驱动初始化 WiFi 分配资源，如 WiFi 控制结构、RX/TX 缓冲区、WiFi NVS 结构等，这个 WiFi 也启动 WiFi 任务。必须先调用此API，然后才能调用所有其他WiFi API
 *  `esp_event_handler_instance_register`，监听`WIFI_EVENT`WiFi 任意事件，触发事件后，进入回调函数
 *  `esp_wifi_set_mode`，设置WiFi工作模式为station、soft-AP或station+soft-AP，默认模式为soft-AP模式。本程序设置为AP
 *  `esp_wifi_set_config`，设置 ESP32 STA 或 AP 的配置
 *  `esp_wifi_start`，根据配置，启动WiFi

## 5.2 注册事件回调函数 ##

*  `WIFI_EVENT_AP_STACONNECTED`：一个station连接到AP时
 *  `WIFI_EVENT_AP_STADISCONNECTED`：一个station断开连接时

static void wifi_event_handler(void* arg, esp_event_base_t event_base, int32_t event_id, void* event_data)
    { 
        if (event_id == WIFI_EVENT_AP_STACONNECTED) { 
            wifi_event_ap_staconnected_t* event = (wifi_event_ap_staconnected_t*) event_data;
            ESP_LOGI(TAG, "station "MACSTR" join, AID=%d", MAC2STR(event->mac), event->aid);
        } else if (event_id == WIFI_EVENT_AP_STADISCONNECTED) { 
            wifi_event_ap_stadisconnected_t* event = (wifi_event_ap_stadisconnected_t*) event_data;
            ESP_LOGI(TAG, "station "MACSTR" leave, AID=%d", MAC2STR(event->mac), event->aid);
        }
    }

# 六、关键函数 #

## 6.1 将事件回调函数注册到特定循环 ##

*  `[in] event_base`：要为其注册事件的基本 ID
 *  `[in] event_id`：要为其注册事件的 ID
 *  `[in] event_handler`：事件被调度时的回调函数
 *  `[in] event_handler_arg`：事件被调度时的回调函数的参数
 *  `[out] instance`：事件被调度时的回调函数的实例，取消该注册所必须的参数。如果不取消，则可以不保存

esp_err_t esp_event_handler_instance_register(esp_event_base_t event_base, int32_t  event_id, esp_event_handler_t event_handler, void *event_handler_arg, esp_event_handler_instance_t *instance)

## 6.2 设置 ESP32 STA 或 AP 的配置 ##

*  `interface`：`WIFI_IF_STA`或者`WIFI_IF_AP`
 *  `conf`：配置参数，有两种`wifi_sta_config_t`或者`wifi_ap_config_t`

esp_err_t esp_wifi_set_config(wifi_interface_t interface, wifi_config_t *conf)

/** @brief STA configuration settings for the ESP32 */
    typedef struct { 
        uint8_t ssid[32];      /**< SSID of target AP. */
        uint8_t password[64];  /**< Password of target AP. */
        wifi_scan_method_t scan_method;    /**< do all channel scan or fast scan */
        bool bssid_set;        /**< whether set MAC address of target AP or not. Generally, station_config.bssid_set needs to be 0; and it needs to be 1 only when users need to check the MAC address of the AP.*/
        uint8_t bssid[6];     /**< MAC address of target AP*/
        uint8_t channel;       /**< channel of target AP. Set to 1~13 to scan starting from the specified channel before connecting to AP. If the channel of AP is unknown, set it to 0.*/
        uint16_t listen_interval;   /**< Listen interval for ESP32 station to receive beacon when WIFI_PS_MAX_MODEM is set. Units: AP beacon intervals. Defaults to 3 if set to 0. */
        wifi_sort_method_t sort_method;    /**< sort the connect AP in the list by rssi or security mode */
        wifi_scan_threshold_t  threshold;     /**< When sort_method is set, only APs which have an auth mode that is more secure than the selected auth mode and a signal stronger than the minimum RSSI will be used. */
        wifi_pmf_config_t pmf_cfg;    /**< Configuration for Protected Management Frame. Will be advertized in RSN Capabilities in RSN IE. */
        uint32_t rm_enabled:1;        /**< Whether Radio Measurements are enabled for the connection */
        uint32_t btm_enabled:1;       /**< Whether BSS Transition Management is enabled for the connection */
        uint32_t reserved:30;         /**< Reserved for future feature set */
    } wifi_sta_config_t;
    
    /** @brief Soft-AP configuration settings for the ESP32 */
    typedef struct { 
        uint8_t ssid[32];           /**< SSID of ESP32 soft-AP. If ssid_len field is 0, this must be a Null terminated string. Otherwise, length is set according to ssid_len. */
        uint8_t password[64];       /**< Password of ESP32 soft-AP. */
        uint8_t ssid_len;           /**< Optional length of SSID field. */
        uint8_t channel;            /**< Channel of ESP32 soft-AP */
        wifi_auth_mode_t authmode;  /**< Auth mode of ESP32 soft-AP. Do not support AUTH_WEP in soft-AP mode */
        uint8_t ssid_hidden;        /**< Broadcast SSID or not, default 0, broadcast the SSID */
        uint8_t max_connection;     /**< Max number of stations allowed to connect in, default 4, max 10 */
        uint16_t beacon_interval;   /**< Beacon interval which should be multiples of 100. Unit: TU(time unit, 1 TU = 1024 us). Range: 100 ~ 60000. Default value: 100 */
        wifi_cipher_type_t pairwise_cipher;   /**< pairwise cipher of SoftAP, group cipher will be derived using this. cipher values are valid starting from WIFI_CIPHER_TYPE_TKIP, enum values before that will be considered as invalid and default cipher suites(TKIP+CCMP) will be used. Valid cipher suites in softAP mode are WIFI_CIPHER_TYPE_TKIP, WIFI_CIPHER_TYPE_CCMP and WIFI_CIPHER_TYPE_TKIP_CCMP. */
        bool ftm_responder;         /**< Enable FTM Responder mode */
    } wifi_ap_config_t;
    
    typedef union { 
        wifi_ap_config_t  ap;  /**< configuration of AP */
        wifi_sta_config_t sta; /**< configuration of STA */
    } wifi_config_t;

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[ESP32-C3_ _VS Code_Hello World]: https://blog.csdn.net/kangweijian/article/details/120284617
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