fix case of connecting when wifi is stopped

Author: anecdata

ports/esp32s2/common-hal/wifi/Radio.c

@@ -126,15 +126,25 @@ void common_hal_wifi_radio_set_hostname(wifi_radio_obj_t *self, const char *host
 }
 
 wifi_radio_error_t common_hal_wifi_radio_connect(wifi_radio_obj_t *self, uint8_t* ssid, size_t ssid_len, uint8_t* password, size_t password_len, uint8_t channel, mp_float_t timeout, uint8_t* bssid, size_t bssid_len) {
+    if (!common_hal_wifi_radio_get_enabled(self)) {
+        mp_raise_RuntimeError(translate("Can't connect when wifi is not enabled"));
+    }
+
     EventBits_t bits;
+    // can't block since both bits are false after wifi_init
+    // both bits are true after an existing connection stops
     bits = xEventGroupWaitBits(self->event_group_handle,
         WIFI_CONNECTED_BIT | WIFI_DISCONNECTED_BIT,
         pdTRUE,
         pdTRUE,
         0);
-        if ((bits & WIFI_CONNECTED_BIT) != 0) {
-            return WIFI_RADIO_ERROR_NONE;
-        }
+    if (((bits & WIFI_CONNECTED_BIT) != 0) &&
+        !((bits & WIFI_DISCONNECTED_BIT) != 0)) {
+        return WIFI_RADIO_ERROR_NONE;
+    }
+    // explicitly clear bits since xEventGroupWaitBits may have timed out
+    xEventGroupClearBits(self->event_group_handle, WIFI_CONNECTED_BIT);
+    xEventGroupClearBits(self->event_group_handle, WIFI_DISCONNECTED_BIT);
     start_station(self);
 
     wifi_config_t* config = &self->sta_config;