54.1 引言

探索完4G模块的应用、蓝牙模块的应用，最近开始了WiFi模块的使用。WiFi模块我们选择了广泛应用的esp32WiFi模组，所以就重新踏入了WiFi探索之旅。

然后项目上要用到WiFi的AP+STA模式，并且要开启NAT模式，就是WiFi模块能连接路由器，然后手机能连接WiFi模块，然后手机通过WiFi模块连接到路由器，能通过WiFi模块上网。

54.2 AP+STA+IP_NAPT代码

话不多说，先上app_main.c代码。这个代码也是网上搜集到的，自己理解后翻炒了一遍吧。。

#include <string.h>
#include "freertos/FreeRTOS.h"
#include "freertos/task.h"
#include "freertos/event_groups.h"
#include "esp_system.h"
#include "esp_wifi.h"
#include "esp_wpa2.h"
#include "esp_event.h"
#include "esp_log.h"
#include "nvs_flash.h"
#include "driver/gpio.h"
#include "lwip/opt.h"

#if IP_NAPT
#include "lwip/lwip_napt.h"
#endif

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

#define MY_DNS_IP_ADDR 				0x08080808 // 8.8.8.8

//模块AP自己的SSID和PWD
#define HT_ESP32_AP_SSID 			CONFIG_ESP_AP_SSID
#define HT_ESP32_AP_PASS 			CONFIG_ESP_AP_PASSWORD
//连接路由的SSID和PWD
#define HT_ESP32_STA_SSID      		"hello"
#define HT_ESP32_STA_PASS      		"world"

#define HT_ESP32_MAXIMUM_RETRY		(10)

/* FreeRTOS event group to signal when we are connected*/
static EventGroupHandle_t 			s_wifi_event_group;

/* The event group allows multiple bits for each event, but we only care about one event
 * - are we connected to the AP with an IP? */
const int WIFI_CONNECTED_BIT = BIT0;

static const char *TAG = "wifi apsta";

static int s_retry_num = 0;

static esp_err_t event_handler(void *ctx, system_event_t *event)
{
  switch(event->event_id) {
  case SYSTEM_EVENT_STA_START:
    esp_wifi_connect();
    break;
  case SYSTEM_EVENT_STA_GOT_IP:
    ESP_LOGI(TAG, "got ip:" IPSTR, IP2STR(&event->event_info.got_ip.ip_info.ip));
    s_retry_num = 0;
    xEventGroupSetBits(s_wifi_event_group, WIFI_CONNECTED_BIT);
    break;
  case SYSTEM_EVENT_STA_DISCONNECTED:
    {

	
      if (s_retry_num < HT_ESP32_MAXIMUM_RETRY) 
	  {
		esp_wifi_connect();
		xEventGroupClearBits(s_wifi_event_group, WIFI_CONNECTED_BIT);
		s_retry_num++;
		ESP_LOGI(TAG,"retry to connect to the AP");
      }
      ESP_LOGI(TAG,"connect to the AP failed:%d", event->event_info.disconnected.reason);
      break;
    }
  case SYSTEM_EVENT_AP_STACONNECTED:
    ESP_LOGI(TAG,"station connected");
    break;
  case SYSTEM_EVENT_AP_STADISCONNECTED:
    ESP_LOGI(TAG,"station disconnected");
    break;
  default:
    break;
  }
  return ESP_OK;
}

void wifi_init_sta()
{
    ip_addr_t dnsserver;
    //tcpip_adapter_dns_info_t dnsinfo;

    s_wifi_event_group = xEventGroupCreate();

    tcpip_adapter_init();
    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_storage(WIFI_STORAGE_RAM));
    ESP_ERROR_CHECK(esp_wifi_set_mode(WIFI_MODE_APSTA));


    /* ESP STATION CONFIG */
    wifi_config_t sta_config = {
	.sta = {
		    .ssid 		= HT_ESP32_STA_SSID,
		    .password 	= HT_ESP32_STA_PASS,
			/* 设置密码意味着工作站将连接到所有安全模式，包括WEP/WPA.
			 * However these modes are deprecated and not advisable to be used. Incase your Access point
			 * doesn't support WPA2, these mode can be enabled by commenting below line */
			.threshold.authmode = WIFI_AUTH_WPA2_PSK,
			.bssid_set = false,

			.pmf_cfg = {
				.capable = true,
				.required = false
			},
		},
    };

    /* ESP AP CONFIG */
    wifi_config_t ap_config = {
	.ap = {
	    .ssid 			= HT_ESP32_AP_SSID,
	    .channel 		= 0,
	    .authmode 		= WIFI_AUTH_WPA2_PSK,
	    .password 		= HT_ESP32_AP_PASS,
	    .ssid_hidden 	= 0,
	    .max_connection	= 4,
	    .beacon_interval = 100
	}
    };

    ESP_ERROR_CHECK(esp_wifi_set_config(ESP_IF_WIFI_STA, &sta_config) );
    ESP_ERROR_CHECK(esp_wifi_set_config(ESP_IF_WIFI_AP, &ap_config) );

    // Enable DNS (offer) for dhcp server
    dhcps_offer_t dhcps_dns_value = OFFER_DNS;
    dhcps_set_option_info(6, &dhcps_dns_value, sizeof(dhcps_dns_value));

    // Set custom dns server address for dhcp server
    dnsserver.u_addr.ip4.addr = htonl(MY_DNS_IP_ADDR);
    dnsserver.type = IPADDR_TYPE_V4;
    dhcps_dns_setserver(&dnsserver);

    //tcpip_adapter_get_dns_info(TCPIP_ADAPTER_IF_AP, TCPIP_ADAPTER_DNS_MAIN, &dnsinfo);
   // ESP_LOGI(TAG, "DNS IP:" IPSTR, IP2STR(&dnsinfo.ip.u_addr.ip4));

    ESP_ERROR_CHECK(esp_wifi_start());

    ESP_LOGI(TAG, "wifi_init_apsta finished.");
    ESP_LOGI(TAG, "connect to ap SSID: %s ", sta_config.sta.ssid);
}

static void htHrint_task(void *pvParameters)
{
	while(1)
	{
		ESP_LOGI(TAG, "hello world\r\n");
		vTaskDelay(1000 / portTICK_PERIOD_MS);	/* 延时1000ms*/
	}
}


void app_main()
{
  // Initialize NVS
  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);

  // Setup WIFI
  wifi_init_sta();
//这里就是打开nat转换的代码，但是除了代码这里要有，还需要配置
#if IP_NAPT
  u32_t napt_netif_ip = 0xC0A80401; // Set to ip address of softAP netif (Default is 192.168.4.1)
  ip_napt_enable(htonl(napt_netif_ip), 1);
  ESP_LOGI(TAG, "------------------------>NAT is enabled");
#endif

	xTaskCreate(htHrint_task, "HTTask", 4096, NULL, 5, NULL);


}