add feature of simple wifi example

Closes: https://github.com/espressif/esp-idf/issues/1433

examples/wifi/simple_wifi/Makefile

@@ -0,0 +1,9 @@
+#
+# This is a project Makefile. It is assumed the directory this Makefile resides in is a
+# project subdirectory.
+#
+
+PROJECT_NAME := simple_wifi
+
+include $(IDF_PATH)/make/project.mk
+

examples/wifi/simple_wifi/main/Kconfig.projbuild

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+menu "Example Configuration"
+
+choice ESP_WIFI_MODE
+    prompt "AP or STA"
+    default ESP_WIFI_IS_STATION
+    help
+        Whether the esp32 is softAP or station.
+
+config ESP_WIFI_IS_SOFTAP
+    bool "SoftAP"
+config ESP_WIFI_IS_STATION
+    bool "Station"
+endchoice
+
+config ESP_WIFI_MODE_AP
+    bool
+    default y if ESP_WIFI_IS_SOFTAP
+    default n if ESP_WIFI_IS_STATION
+
+config ESP_WIFI_SSID
+    string "WiFi SSID"
+    default "myssid"
+    help
+	SSID (network name) for the example to connect to.
+
+config ESP_WIFI_PASSWORD
+    string "WiFi Password"
+    default "mypassword"
+    help
+	WiFi password (WPA or WPA2) for the example to use.
+		
+config MAX_STA_CONN
+    int "Max STA conn"
+    default 4
+    help
+	Max number of the STA connects to AP.
+endmenu

examples/wifi/simple_wifi/main/component.mk

@@ -0,0 +1,8 @@
+#
+# Main component makefile.
+#
+# This Makefile can be left empty. By default, it will take the sources in the 
+# src/ directory, compile them and link them into lib(subdirectory_name).a 
+# in the build directory. This behaviour is entirely configurable,
+# please read the ESP-IDF documents if you need to do this.
+#

examples/wifi/simple_wifi/main/simple_wifi.c

@@ -0,0 +1,147 @@
+/* Simple WiFi Example
+
+   This example code is in the Public Domain (or CC0 licensed, at your option.)
+
+   Unless required by applicable law or agreed to in writing, this
+   software is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR
+   CONDITIONS OF ANY KIND, either express or implied.
+*/
+#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_event_loop.h"
+#include "esp_log.h"
+#include "nvs_flash.h"
+
+#include "lwip/err.h"
+#include "lwip/sys.h"
+
+/* The examples use simple WiFi configuration that you can set via
+   'make menuconfig'.
+
+   If you'd rather not, just change the below entries to strings with
+   the config you want - ie #define EXAMPLE_WIFI_SSID "mywifissid"
+*/
+#define EXAMPLE_ESP_WIFI_MODE_AP   CONFIG_ESP_WIFI_MODE_AP //TRUE:AP FALSE:STA
+#define EXAMPLE_ESP_WIFI_SSID      CONFIG_ESP_WIFI_SSID
+#define EXAMPLE_ESP_WIFI_PASS      CONFIG_ESP_WIFI_PASSWORD
+#define EXAMPLE_MAX_STA_CONN       CONFIG_MAX_STA_CONN
+
+/* FreeRTOS event group to signal when we are connected*/
+static EventGroupHandle_t 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 = "simple wifi";
+
+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:%s",
+                 ip4addr_ntoa(&event->event_info.got_ip.ip_info.ip));
+        xEventGroupSetBits(wifi_event_group, WIFI_CONNECTED_BIT);
+        break;
+    case SYSTEM_EVENT_AP_STACONNECTED:
+        ESP_LOGI(TAG, "station:"MACSTR" join, AID=%d",
+                 MAC2STR(event->event_info.sta_connected.mac),
+                 event->event_info.sta_connected.aid);
+        break;
+    case SYSTEM_EVENT_AP_STADISCONNECTED:
+        ESP_LOGI(TAG, "station:"MACSTR"leave, AID=%d",
+                 MAC2STR(event->event_info.sta_disconnected.mac),
+                 event->event_info.sta_disconnected.aid);
+        break;
+    case SYSTEM_EVENT_STA_DISCONNECTED:
+        esp_wifi_connect();
+        xEventGroupClearBits(wifi_event_group, WIFI_CONNECTED_BIT);
+        break;
+    default:
+        break;
+    }
+    return ESP_OK;
+}
+
+void wifi_init_softap()
+{
+    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));
+    wifi_config_t wifi_config = {
+        .ap = {
+            .ssid = EXAMPLE_ESP_WIFI_SSID,
+            .ssid_len = strlen(EXAMPLE_ESP_WIFI_SSID),
+            .password = EXAMPLE_ESP_WIFI_PASS,
+            .max_connection = EXAMPLE_MAX_STA_CONN,
+            .authmode = WIFI_AUTH_WPA_WPA2_PSK
+        },
+    };
+    if (strlen(EXAMPLE_ESP_WIFI_PASS) == 0) {
+        wifi_config.ap.authmode = WIFI_AUTH_OPEN;
+    }
+
+    ESP_ERROR_CHECK(esp_wifi_set_mode(WIFI_MODE_AP));
+    ESP_ERROR_CHECK(esp_wifi_set_config(ESP_IF_WIFI_AP, &wifi_config));
+    ESP_ERROR_CHECK(esp_wifi_start());
+
+    ESP_LOGI(TAG, "wifi_init_softap finished.SSID:%s password:%s",
+             EXAMPLE_ESP_WIFI_SSID, EXAMPLE_ESP_WIFI_PASS);
+}
+
+void wifi_init_sta()
+{
+    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));
+    wifi_config_t wifi_config = {
+        .sta = {
+            .ssid = EXAMPLE_ESP_WIFI_SSID,
+            .password = EXAMPLE_ESP_WIFI_PASS
+        },
+    };
+
+    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, "wifi_init_sta finished.");
+    ESP_LOGI(TAG, "connect to ap SSID:%s password:%s",
+             EXAMPLE_ESP_WIFI_SSID, EXAMPLE_ESP_WIFI_PASS);
+}
+
+void app_main()
+{
+    //Initialize NVS
+    esp_err_t ret = nvs_flash_init();
+    if (ret == ESP_ERR_NVS_NO_FREE_PAGES) {
+      ESP_ERROR_CHECK(nvs_flash_erase());
+      ret = nvs_flash_init();
+    }
+    ESP_ERROR_CHECK(ret);
+    
+#if EXAMPLE_ESP_WIFI_MODE_AP
+    ESP_LOGI(TAG, "ESP_WIFI_MODE_AP");
+    wifi_init_softap();
+#else
+    ESP_LOGI(TAG, "ESP_WIFI_MODE_STA");
+    wifi_init_sta();
+#endif /*EXAMPLE_ESP_WIFI_MODE_AP*/
+
+}