Added wifi connection example

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 := 02_wifi_connection
+
+include $(IDF_PATH)/make/project.mk
+

main/main.c

@@ -0,0 +1,102 @@
+#include <stdio.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"
+
+#define WIFI_SSID "MYSSID"
+#define WIFI_PASS "MYPASSWORD"
+
+
+// Event group
+static EventGroupHandle_t wifi_event_group;
+const int CONNECTED_BIT = BIT0;
+
+
+// Wifi event handler
+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:
+        xEventGroupSetBits(wifi_event_group, CONNECTED_BIT);
+        break;
+    
+	case SYSTEM_EVENT_STA_DISCONNECTED:
+		xEventGroupClearBits(wifi_event_group, CONNECTED_BIT);
+        break;
+    
+	default:
+        break;
+    }
+   
+	return ESP_OK;
+}
+
+
+// Main task
+void main_task(void *pvParameter)
+{
+	// wait for connection
+	printf("Main task: waiting for connection to the wifi network... ");
+	xEventGroupWaitBits(wifi_event_group, CONNECTED_BIT, false, true, portMAX_DELAY);
+	printf("connected!\n");
+	
+	// print the local IP address
+	tcpip_adapter_ip_info_t ip_info;
+	ESP_ERROR_CHECK(tcpip_adapter_get_ip_info(TCPIP_ADAPTER_IF_STA, &ip_info));
+	printf("IP Address:  %s\n", ip4addr_ntoa(&ip_info.ip));
+	printf("Subnet mask: %s\n", ip4addr_ntoa(&ip_info.netmask));
+	printf("Gateway:     %s\n", ip4addr_ntoa(&ip_info.gw));
+	
+	while(1) {
+		vTaskDelay(1000 / portTICK_RATE_MS);
+	}
+}
+
+
+// Main application
+void app_main()
+{
+	// disable the default wifi logging
+	esp_log_level_set("wifi", ESP_LOG_NONE);
+	
+	// disable stdout buffering
+	setvbuf(stdout, NULL, _IONBF, 0);
+	
+	// create the event group to handle wifi events
+	wifi_event_group = xEventGroupCreate();
+		
+	// initialize the tcp stack
+	tcpip_adapter_init();
+
+	// initialize the wifi event handler
+	ESP_ERROR_CHECK(esp_event_loop_init(event_handler, NULL));
+	
+	// initialize the wifi stack in STAtion mode with config in RAM
+	wifi_init_config_t wifi_init_config = WIFI_INIT_CONFIG_DEFAULT();
+	ESP_ERROR_CHECK(esp_wifi_init(&wifi_init_config));
+	ESP_ERROR_CHECK(esp_wifi_set_storage(WIFI_STORAGE_RAM));
+	ESP_ERROR_CHECK(esp_wifi_set_mode(WIFI_MODE_STA));
+
+	// configure the wifi connection and start the interface
+	wifi_config_t wifi_config = {
+        .sta = {
+            .ssid = WIFI_SSID,
+            .password = WIFI_PASS,
+        },
+    };
+	ESP_ERROR_CHECK(esp_wifi_set_config(ESP_IF_WIFI_STA, &wifi_config));
+    ESP_ERROR_CHECK(esp_wifi_start());
+	printf("Connecting to %s\n", WIFI_SSID);
+	
+	// start the main task
+    xTaskCreate(&main_task, "main_task", 2048, NULL, 5, NULL);
+}