基于ESP-IDF4.1版本

main.c文件如下：

#include
#include "freertos/FreeRTOS.h"
#include "freertos/task.h"
#include "freertos/event_groups.h"
#include "esp_system.h"
#include "esp_wifi.h"
#include "esp_event.h"
#include "esp_log.h"
#include "nvs_flash.h"
#include "esp_pm.h"

#include "lwip/err.h"
#include "lwip/sys.h"

//值在sdkconfig中配置
#define ESP_WIFI_SSID CONFIG_ESP_WIFI_SSID
#define ESP_WIFI_PASS CONFIG_ESP_WIFI_PASSWORD
#define ESP_MAXIMUM_RETRY CONFIG_ESP_MAXIMUM_RETRY

#define DEFAULT_LISTEN_INTERVAL CONFIG_WIFI_LISTEN_INTERVAL
#define DEFAULT_PS_MODE WIFI_PS_MIN_MODEM

//事件的位，连接成功和失败
#define WIFI_CONNECTED_BIT BIT0
#define WIFI_FAIL_BIT BIT1

//FreeRTOS事件组用于表示什么时候建立连接
static EventGroupHandle_t s_wifi_event_group;

static const char *TAG = "wifi station";

static int s_retry_num = 0;

//事件处理服务
static void event_handler(void* arg, esp_event_base_t event_base, int32_t event_id, void* event_data)
{
if (event_base == WIFI_EVENT && event_id == WIFI_EVENT_STA_START) {
esp_wifi_connect();
} else if (event_base == WIFI_EVENT && event_id == WIFI_EVENT_STA_DISCONNECTED) {
if (s_retry_num < ESP_MAXIMUM_RETRY) { esp_wifi_connect(); s_retry_num++; ESP_LOGI(TAG, "retry to connect to the AP"); } else { //事件组置位 xEventGroupSetBits(s_wifi_event_group, WIFI_FAIL_BIT); } ESP_LOGI(TAG,"connect to the AP fail"); } else if (event_base == IP_EVENT && event_id == IP_EVENT_STA_GOT_IP) { ip_event_got_ip_t* event = (ip_event_got_ip_t*) event_data; ESP_LOGI(TAG, "got ip:" IPSTR, IP2STR(&event->ip_info.ip));
s_retry_num = 0;
//事件组置位
xEventGroupSetBits(s_wifi_event_group, WIFI_CONNECTED_BIT);
}
}

//wifi初始化
void wifi_init_sta(void)
{
//创建事件组
s_wifi_event_group = xEventGroupCreate();

ESP\_ERROR\_CHECK(esp\_netif\_init());  
ESP\_ERROR\_CHECK(esp\_event\_loop\_create\_default());  
esp\_netif\_t \*sta\_netif = esp\_netif\_create\_default\_wifi\_sta();  
assert(sta\_netif);

wifi\_init\_config\_t cfg = WIFI\_INIT\_CONFIG\_DEFAULT();  
ESP\_ERROR\_CHECK(esp\_wifi\_init(&cfg));

//注册事件处理服务  
ESP\_ERROR\_CHECK(esp\_event\_handler\_register(WIFI\_EVENT, ESP\_EVENT\_ANY\_ID, &event\_handler, NULL));  
ESP\_ERROR\_CHECK(esp\_event\_handler\_register(IP\_EVENT, IP\_EVENT\_STA\_GOT\_IP, &event\_handler, NULL));

wifi\_config\_t wifi\_config = {  
    .sta = {  
        .ssid = ESP\_WIFI\_SSID,  
        .password = ESP\_WIFI\_PASS,  
        //设备从AP监听信标的间隔  
        .listen\_interval = DEFAULT\_LISTEN\_INTERVAL,  
        //设置密码意味着设备将会连接所有安全的模式，包括WEP、WPA。然而这些模式不建议使用，如果你的接入点不支持WPA2，注释以下行来启用其他模式  
        .threshold.authmode = WIFI\_AUTH\_WPA2\_PSK,

        .pmf\_cfg = {  
            .capable = true,  
            .required = false  
        },  
    },  
};  
ESP\_ERROR\_CHECK(esp\_wifi\_set\_mode(WIFI\_MODE\_STA) );  
ESP\_ERROR\_CHECK(esp\_wifi\_set\_config(ESP\_IF\_WIFI\_STA, &wifi\_config) );  
ESP\_ERROR\_CHECK(esp\_wifi\_start() );  
ESP\_LOGI(TAG, "esp\_wifi\_set\_ps().");  
esp\_wifi\_set\_ps(DEFAULT\_PS\_MODE);  
ESP\_LOGI(TAG, "wifi\_init\_sta finished.");

//事件组等待位，等到连接建立或者超过最大重连数后连接仍然失败。位的设置是通过事件处理服务  
EventBits\_t bits = xEventGroupWaitBits(s\_wifi\_event\_group,  
        WIFI\_CONNECTED\_BIT | WIFI\_FAIL\_BIT,  
        pdFALSE,  
        pdFALSE,  
        portMAX\_DELAY);

//通过事件组等待位返回位的值，判断事件做了什么  
if (bits & WIFI\_CONNECTED\_BIT) {  
    ESP\_LOGI(TAG, "connected to ap SSID:%s password:%s",  
             ESP\_WIFI\_SSID, ESP\_WIFI\_PASS);  
} else if (bits & WIFI\_FAIL\_BIT) {  
    ESP\_LOGI(TAG, "Failed to connect to SSID:%s, password:%s",  
             ESP\_WIFI\_SSID, ESP\_WIFI\_PASS);  
} else {  
    ESP\_LOGE(TAG, "UNEXPECTED EVENT");  
}

//注销事件处理服务，注销后，即便此前已注册的事件再次被发送时，也不会再执行了。  
ESP\_ERROR\_CHECK(esp\_event\_handler\_unregister(IP\_EVENT, IP\_EVENT\_STA\_GOT\_IP, &event\_handler));  
ESP\_ERROR\_CHECK(esp\_event\_handler\_unregister(WIFI\_EVENT, ESP\_EVENT\_ANY\_ID, &event\_handler));  
vEventGroupDelete(s\_wifi\_event\_group);  

}

//启动
void app_main(void)
{
//初始化非易失性存储
esp_err_t ret = nvs_flash_init();
if (ret == ESP_ERR_NVS_NO_FREE_PAGES || ret == ESP_ERR_NVS_NEW_VERSION_FOUND) {
ESP_ERROR_CHECK(nvs_flash_erase());
ret = nvs_flash_init();
}
ESP_ERROR_CHECK(ret);

//配置动态频率缩放：最高频率和最低频率在sdkconfig中配置  
esp\_pm\_config\_esp32\_t pm\_config = {  
        .max\_freq\_mhz = CONFIG\_MAX\_CPU\_FREQ\_MHZ,  
        .min\_freq\_mhz = CONFIG\_MIN\_CPU\_FREQ\_MHZ,  
        .light\_sleep\_enable = true  
};

ESP\_LOGI(TAG, "ESP\_WIFI\_MODE\_STA");  
wifi\_init\_sta();  

}

Kconfig.projbuild文件如下：

menu "Example Configuration"

config ESP\_WIFI\_SSID  
    string "WiFi SSID"  
    default "wifissid"  
    help  
        SSID (network name) for the example to connect to.

config ESP\_WIFI\_PASSWORD  
    string "WiFi Password"  
    default "wifipassword"  
    help  
        WiFi password (WPA or WPA2) for the example to use.

config ESP\_MAXIMUM\_RETRY  
    int "Maximum retry"  
    default 5  
    help  
        Set the Maximum retry to avoid station reconnecting to the AP unlimited when the AP is really inexistent.

config WIFI\_LISTEN\_INTERVAL  
    int "WiFi listen interval"  
    default 3  
    help  
        Interval for station to listen to beacon from AP. The unit of listen interval is one beacon interval.  
        For example, if beacon interval is 100 ms and listen interval is 3, the interval for station to listen  
        to beacon is 300 ms.

choice POWER\_SAVE\_MODE  
    prompt "power save mode"  
    default POWER\_SAVE\_MIN\_MODEM  
    help  
        Power save mode for the esp32 to use. Modem sleep mode includes minimum and maximum power save modes.  
        In minimum power save mode, station wakes up every DTIM to receive beacon. Broadcast data will not be  
        lost because it is transmitted after DTIM. However, it can not save much more power if DTIM is short  
        for DTIM is determined by AP.  
        In maximum power save mode, station wakes up every listen interval to receive beacon. Broadcast data  
        may be lost because station may be in sleep state at DTIM time. If listen interval is longer, more power  
        is saved but broadcast data is more easy to lose.

    config POWER\_SAVE\_NONE  
        bool "none"  
    config POWER\_SAVE\_MIN\_MODEM  
        bool "minimum modem"  
    config POWER\_SAVE\_MAX\_MODEM  
        bool "maximum modem"  
endchoice

choice MAX\_CPU\_FREQ  
    prompt "Maximum CPU frequency"  
    default MAX\_CPU\_FREQ\_80  
    help  
        Maximum CPU frequency to use for dynamic frequency scaling.

    config MAX\_CPU\_FREQ\_80  
        bool "80 MHz"  
    config MAX\_CPU\_FREQ\_160  
        bool "160 MHz"  
    config MAX\_CPU\_FREQ\_240  
        bool "240 MHz"  
endchoice

config MAX\_CPU\_FREQ\_MHZ  
    int  
    default 80 if MAX\_CPU\_FREQ\_80  
    default 160 if MAX\_CPU\_FREQ\_160  
    default 240 if MAX\_CPU\_FREQ\_240

choice MIN\_CPU\_FREQ  
    prompt "Minimum CPU frequency"  
    default MIN\_CPU\_FREQ\_10M  
    help  
        Minimum CPU frequency to use for dynamic frequency scaling.  
        Should be set to XTAL frequency or XTAL frequency divided by integer.

    config MIN\_CPU\_FREQ\_40M  
        bool "40 MHz (use with 40MHz XTAL)"  
        depends on ESP32\_XTAL\_FREQ\_40 || ESP32\_XTAL\_FREQ\_AUTO  
    config MIN\_CPU\_FREQ\_20M  
        bool "20 MHz (use with 40MHz XTAL)"  
        depends on ESP32\_XTAL\_FREQ\_40 || ESP32\_XTAL\_FREQ\_AUTO  
    config MIN\_CPU\_FREQ\_10M  
        bool "10 MHz (use with 40MHz XTAL)"  
        depends on ESP32\_XTAL\_FREQ\_40 || ESP32\_XTAL\_FREQ\_AUTO  
    config MIN\_CPU\_FREQ\_26M  
        bool "26 MHz (use with 26MHz XTAL)"  
        depends on ESP32\_XTAL\_FREQ\_26 || ESP32\_XTAL\_FREQ\_AUTO  
    config MIN\_CPU\_FREQ\_13M  
        bool "13 MHz (use with 26MHz XTAL)"  
        depends on ESP32\_XTAL\_FREQ\_26 || ESP32\_XTAL\_FREQ\_AUTO  
endchoice

config MIN\_CPU\_FREQ\_MHZ  
    int  
    default 40 if MIN\_CPU\_FREQ\_40M  
    default 20 if MIN\_CPU\_FREQ\_20M  
    default 10 if MIN\_CPU\_FREQ\_10M  
    default 26 if MIN\_CPU\_FREQ\_26M  
    default 13 if MIN\_CPU\_FREQ\_13M

endmenu

原文：https://gitee.com/EspressifSystems/esp-idf