do wifi connection in loop

src/main.cpp

@@ -98,19 +98,8 @@ void setup()
   flip.sendRaw(rawBuff, sizeof(rawBuff));
 
   /* attempt to connect to Wifi network */
-  Serial.print("Connecting to Wifi SSID ");
-  Serial.print(WIFI_SSID);
   WiFi.setHostname(HOSTNAME);
   WiFi.begin(WIFI_SSID, WIFI_PASSWORD);
-  while (WiFi.status() != WL_CONNECTED)
-  {
-    Serial.print("!");
-    Serial.print(WiFi.status());
-    Serial.print(".");
-    delay(500);
-  }
-  Serial.print("\nWiFi connected. IP address: ");
-  Serial.println(WiFi.localIP());
 
   /* get internet time */
   Serial.print("Retrieving time: ");
@@ -127,32 +116,70 @@ void setup()
 
   /* setup ArduinoOTA */
   ArduinoOTA.setHostname(HOSTNAME);
-  ArduinoOTA.begin();
   ArduinoOTA.onStart(onOTAStart);
-
-  /* initialize and connect telegram bot */
-  tele.init();
-
-  /* initialy print closed at the display */
-  printClose("");
 }
 
 void loop()
 {
+  static wl_status_t oldWifiStatus = WL_DISCONNECTED;
   unsigned long now = millis();
   static unsigned long lastDisplayRefresh = now;
   static unsigned long lastTelegramRefresh = now;
 
-  /* OTA handling */
-  ArduinoOTA.handle();
-
-  yield();
-
-  /* Telegram handling */
-  if ((now - lastTelegramRefresh) > 5000)
+  if (WiFi.status() == WL_CONNECTED)
   {
-    lastTelegramRefresh = now;
-    tele.cyclic(now);
+    // if the Wifi is connected do all the internet stuff
+    if (WiFi.status() != oldWifiStatus)
+    {
+      /* we freshly reconnected so tell everybody that we are online */
+      Serial.print("\nWiFi connected. IP address: ");
+      Serial.println(WiFi.localIP());
+
+      Serial.print("Retrieving time: ");
+      configTime(0, 0, "pool.ntp.org"); // get UTC time via NTP
+      configTzTime("CET-1CEST,M3.5.0,M10.5.0/3", "pool.ntp.org");
+      time_t now = time(nullptr);
+      while (now < 24 * 3600)
+      {
+        Serial.print(".");
+        delay(100);
+        now = time(nullptr);
+      }
+      Serial.println(now);
+
+      ArduinoOTA.begin();
+
+      tele.init();
+
+      printClose("");
+
+      oldWifiStatus = WiFi.status();
+    }
+
+    /* handle the OTA update */
+    ArduinoOTA.handle();
+
+    /* handle Telegram messages */
+    if ((now - lastTelegramRefresh) > 5000)
+    {
+      lastTelegramRefresh = now;
+      tele.cyclic(now);
+    }
+  }
+  else
+  {
+    // if wifi is not connected wait for connection
+    if (WiFi.status() != oldWifiStatus)
+    {
+      /* we freshly disconnected so tell everybody that we are offline */
+      Text = "Wifi \"";
+      Text += WIFI_SSID;
+      Text += "\" not connected";
+
+      ArduinoOTA.end();
+
+      oldWifiStatus = WiFi.status();
+    }
   }
 
   /* FlipDot Handling */
@@ -203,6 +230,12 @@ void loop()
     // send canvas to display
     flip.sendCanvas(&canvas);
   }
+
+  /* wait here if loop execution was faster then 200ms but yield minimum once */
+  do
+  {
+    yield();
+  } while ((millis() - now) < 200);
 }
 
 /* function to write text onto the canvas