Add ability to connect to wifi.

This adds a small subsystem to connect to a basic WPA accesspoint.

1 files changed, 121 insertions, 0 deletions

diff --git a/main/station.c b/main/station.c
new file mode 100644
index 0000000..fa1dd0d
--- /dev/null
+++ b/main/station.c
@@ -0,0 +1,121 @@
+#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.h"
+#include "esp_log.h"
+#include "nvs_flash.h"
+
+#include "lwip/err.h"
+#include "lwip/sys.h"
+
+static EventGroupHandle_t s_wifi_event_group;
+static int s_retry_num = 0;
+static const char * TAG = "wifi";
+
+#define WIFI_CONNECTED_BIT BIT0
+#define WIFI_FAIL_BIT      BIT1
+
+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 < 5) {
+            esp_wifi_connect();
+            s_retry_num++;
+            ESP_LOGI(TAG, "retry to connect to the AP");
+        } else {
+            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;
+        xEventGroupSetBits(s_wifi_event_group, WIFI_CONNECTED_BIT);
+    }
+  }
+
+void wifi_init_station()
+{
+  /** Initialize the flash. Not exactly sure why this is required, but it is,
+   * otherwise there will be a fault. */
+  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);
+
+  ESP_LOGI(TAG, "ESP_WIFI_MODE_STA");
+
+  s_wifi_event_group = xEventGroupCreate();
+
+  ESP_ERROR_CHECK(esp_netif_init());
+  ESP_ERROR_CHECK(esp_event_loop_create_default());
+
+  esp_netif_create_default_wifi_sta();
+
+  wifi_init_config_t cfg = WIFI_INIT_CONFIG_DEFAULT();
+  ESP_ERROR_CHECK(esp_wifi_init(&cfg));
+
+  esp_event_handler_instance_t instance_any_id;
+  esp_event_handler_instance_t instance_got_ip;
+
+  ESP_ERROR_CHECK(
+      esp_event_handler_instance_register(WIFI_EVENT, ESP_EVENT_ANY_ID,
+        &event_handler, NULL, &instance_any_id));
+
+  ESP_ERROR_CHECK(
+      esp_event_handler_instance_register(IP_EVENT, IP_EVENT_STA_GOT_IP,
+        &event_handler, NULL, &instance_got_ip));
+
+    wifi_config_t wifi_config = {
+        .sta = {
+            .ssid = "Wort",
+            .password = "psk",
+            /* Setting a password implies station will connect to all security modes including 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,
+
+            .pmf_cfg = {
+                .capable = true,
+                .required = false
+            },
+        },
+    };
+    ESP_ERROR_CHECK(esp_wifi_set_mode(WIFI_MODE_STA) );
+    ESP_ERROR_CHECK(esp_wifi_set_config(WIFI_IF_STA, &wifi_config) );
+    ESP_ERROR_CHECK(esp_wifi_start() );
+
+    ESP_LOGI(TAG, "wifi_init_sta finished.");
+    /* Waiting until either the connection is established (WIFI_CONNECTED_BIT) or connection failed for the maximum
+     * number of re-tries (WIFI_FAIL_BIT). The bits are set by event_handler() (see above) */
+    EventBits_t bits = xEventGroupWaitBits(s_wifi_event_group,
+            WIFI_CONNECTED_BIT | WIFI_FAIL_BIT,
+            pdFALSE,
+            pdFALSE,
+            portMAX_DELAY);
+
+    /* xEventGroupWaitBits() returns the bits before the call returned, hence we can test which event actually
+     * happened. */
+    if (bits & WIFI_CONNECTED_BIT) {
+        ESP_LOGI(TAG, "connected to ap SSID:%s password:%s",
+                 "Wort", "psk");
+    } else if (bits & WIFI_FAIL_BIT) {
+        ESP_LOGI(TAG, "Failed to connect to SSID:%s, password:%s",
+                 "Wort", "psk");
+    } else {
+        ESP_LOGE(TAG, "UNEXPECTED EVENT");
+    }
+
+    /* The event will not be processed after unregister */
+    ESP_ERROR_CHECK(esp_event_handler_instance_unregister(IP_EVENT, IP_EVENT_STA_GOT_IP, instance_got_ip));
+    ESP_ERROR_CHECK(esp_event_handler_instance_unregister(WIFI_EVENT, ESP_EVENT_ANY_ID, instance_any_id));
+    vEventGroupDelete(s_wifi_event_group);
+}