ESP32-C3入门教程 WiFi篇①——WiFi Scan 快速扫描附近AP无线热点

ゝ一世哀愁。 2022-09-12 13:43 1908阅读 1赞

### 文章目录 ###

*  一、前言
 *  二、快速运行
 *  三、运行效果
 *  四、程序流程
 *  五、关键函数
 *   *  5.1 扫描所有有效的AP
     *  5.2 获取上次扫描中找到的AP列表
     *  5.3 获取上次扫描中找到的AP数

# 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、快速运行 #

*  示例项目中，选择`WiFi`—>`scan`
 *  `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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# 三、运行效果 #

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# 四、程序流程 #

*  `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_sta`，使用默认WiFi Station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_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station
 *  `esp_wifi_start`，根据配置，启动WiFi
 *  `esp_wifi_scan_start`，扫描所有有效的AP
 *  `esp_wifi_scan_get_ap_records`，获取上次扫描中找到的AP列表
 *  `esp_wifi_scan_get_ap_num`，获取上次扫描中找到的AP数

# 五、关键函数 #

## 5.1 扫描所有有效的AP ##

*  `config`，扫描的配置
 *  `block`，是否堵塞程序运行

/** * @brief Scan all available APs. * * @attention If this API is called, the found APs are stored in WiFi driver dynamic allocated memory and the * will be freed in esp_wifi_scan_get_ap_records, so generally, call esp_wifi_scan_get_ap_records to cause * the memory to be freed once the scan is done * @attention The values of maximum active scan time and passive scan time per channel are limited to 1500 milliseconds. * Values above 1500ms may cause station to disconnect from AP and are not recommended. * * @param config configuration of scanning * @param block if block is true, this API will block the caller until the scan is done, otherwise * it will return immediately * * @return * - ESP_OK: succeed * - ESP_ERR_WIFI_NOT_INIT: WiFi is not initialized by esp_wifi_init * - ESP_ERR_WIFI_NOT_STARTED: WiFi was not started by esp_wifi_start * - ESP_ERR_WIFI_TIMEOUT: blocking scan is timeout * - ESP_ERR_WIFI_STATE: wifi still connecting when invoke esp_wifi_scan_start * - others: refer to error code in esp_err.h */
    esp_err_t esp_wifi_scan_start(const wifi_scan_config_t *config, bool block);

## 5.2 获取上次扫描中找到的AP列表 ##

*  `number`，返回的最大ap个数
 *  `ap_records`，返回的app记录数组

/** * @brief Get AP list found in last scan * * @param[inout] number As input param, it stores max AP number ap_records can hold. * As output param, it receives the actual AP number this API returns. * @param ap_records wifi_ap_record_t array to hold the found APs * * @return * - ESP_OK: succeed * - ESP_ERR_WIFI_NOT_INIT: WiFi is not initialized by esp_wifi_init * - ESP_ERR_WIFI_NOT_STARTED: WiFi is not started by esp_wifi_start * - ESP_ERR_INVALID_ARG: invalid argument * - ESP_ERR_NO_MEM: out of memory */
    esp_err_t esp_wifi_scan_get_ap_records(uint16_t *number, wifi_ap_record_t *ap_records);

## 5.3 获取上次扫描中找到的AP数 ##

*  `number`，存储上次扫描中找到的API数

/** * @brief Get number of APs found in last scan * * @param[out] number store number of APs found in last scan * * @attention This API can only be called when the scan is completed, otherwise it may get wrong value. * * @return * - ESP_OK: succeed * - ESP_ERR_WIFI_NOT_INIT: WiFi is not initialized by esp_wifi_init * - ESP_ERR_WIFI_NOT_STARTED: WiFi is not started by esp_wifi_start * - ESP_ERR_INVALID_ARG: invalid argument */
    esp_err_t esp_wifi_scan_get_ap_num(uint16_t *number);

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