diff --git a/platformio.ini b/platformio.ini
index 55f7999..b0dcaf2 100644
--- a/platformio.ini
+++ b/platformio.ini
@@ -12,3 +12,4 @@ lib_deps =
     https://github.com/PaulStoffregen/Time
     TimerOne
     Ethernet
+    PubSubClient3
diff --git a/src/fooclock.ino b/src/fooclock.ino
index 0764b8c..2d675f3 100644
--- a/src/fooclock.ino
+++ b/src/fooclock.ino
@@ -2,11 +2,38 @@
 #include <Ethernet.h>
 #include <SPI.h>
 #include <TimerOne.h>
+#include <PubSubClient.h>
+
+// ---------------- MQTT Settings ------------------
+const char *mqtt_server = "mqtt.chaospott.de"; // <<< anpassen!
+const int mqtt_port = 1883;
+const char *mqtt_client = "fooclock";
+
+// Eindeutige ID für die Uhr in Home Assistant
+const char *device_id = "fooclock_01";
+
+// Topics für Home Assistant
+const char *mqtt_command_topic = "fooclock/display/set"; // Topic zum Senden von Befehlen (ON/OFF)
+const char *mqtt_state_topic = "fooclock/display/state"; // Topic zum Melden des Status (ON/OFF)
+const char *mqtt_discovery_topic = "homeassistant/switch/fooclock/display/config"; // HA Auto-Discovery Topic
+
+EthernetClient ethClient;
+PubSubClient client(ethClient);
+
+bool displayEnabled = true; // Steuerflag für Anzeige
+
+// Forward declaration der neuen Funktionen
+void publishState();
+void publishDiscoveryMessage();
+
+// -------------------------------------------------
 
 #define _A 0
 #define _B 1
 #define _C 2
+#define _D 3
 #define _E 4
+#define _F 5
 #define _G 6
 #define _H 7
 #define _I 8
@@ -28,11 +55,11 @@
 #define _Y 24
 #define _Z 25
 
-#define UP		1
-#define DOWN	2
+#define UP      1
+#define DOWN    2
 
-#define light_lvl_standard	60
-#define light_lvl_risen		255
+#define light_lvl_standard  60
+#define light_lvl_risen     255
 
 // ---------------------------------- Definition of Global Variables -------------------------- //
 
@@ -58,9 +85,9 @@ bool second_changed = false;
 bool init_done = false;
 bool transition_active = false;
 bool swipe_active = false;
-bool shrink_active = false; // Maybe we should move them to a single variable and set or unset bits inside the variable
+bool shrink_active = false;
 int cur_update = 0;
-unsigned int shift_state = 0;
+int shift_state = 0;
 int update_counter = 0;
 int spinner_pos = 0;
 int animation = 0;
@@ -143,6 +170,92 @@ int today[7] = {
     184, 220, 200, 200, 240, 0, 0 // Display "Hello"
 };
 
+
+// ---------------- MQTT Callback ------------------
+void mqttCallback(char *topic, byte *payload, unsigned int length) {
+    payload[length] = '\0'; // String terminieren
+    String message = String((char *) payload);
+    Serial.print("Nachricht empfangen [");
+    Serial.print(topic);
+    Serial.print("] ");
+    Serial.println(message);
+
+    if (String(topic) == mqtt_command_topic) {
+        if (message == "ON") {
+            displayEnabled = true;
+            Serial.println("MQTT: Display eingeschaltet");
+        } else if (message == "OFF") {
+            displayEnabled = false;
+            Serial.println("MQTT: Display ausgeschaltet");
+        }
+        // Sende den neuen Status sofort zurück
+        publishState();
+    }
+}
+
+// ---------------- MQTT Publish State ------------------
+void publishState() {
+    if (displayEnabled) {
+        client.publish(mqtt_state_topic, "ON", true); // true = retain message
+    } else {
+        client.publish(mqtt_state_topic, "OFF", true); // true = retain message
+    }
+}
+
+// ---------------- MQTT Publish Home Assistant Discovery Message ------------------
+void publishDiscoveryMessage() {
+    // Use a fixed-size buffer to create the JSON payload. This is much more
+    // memory-efficient than using the Arduino String class for concatenation.
+    char discoveryPayload[400];
+
+    // Create the JSON payload using snprintf to prevent buffer overflows
+    snprintf(discoveryPayload, sizeof(discoveryPayload),
+             "{"
+             "\"name\":\"FooClock Display\","
+             "\"unique_id\":\"%s_display\","
+             "\"cmd_t\":\"%s\","
+             "\"stat_t\":\"%s\","
+             "\"pl_on\":\"ON\","
+             "\"pl_off\":\"OFF\","
+             "\"icon\":\"mdi:clock-digital\","
+             "\"device\":{"
+             "\"identifiers\":[\"%s\"],"
+             "\"name\":\"FooClock\","
+             "\"manufacturer\":\"DIY\""
+             "}"
+             "}",
+             device_id,
+             mqtt_command_topic,
+             mqtt_state_topic,
+             device_id
+    );
+
+    // Nachricht mit Retain-Flag publishen, damit HA sie auch nach einem Neustart findet
+    client.publish(mqtt_discovery_topic, discoveryPayload, true);
+}
+
+
+// ---------------- MQTT Reconnect ------------------
+void reconnect() {
+    while (!client.connected()) {
+        Serial.print("MQTT Verbindung herstellen...");
+        if (client.connect(mqtt_client)) {
+            Serial.println("verbunden.");
+            // Sobald verbunden, Befehls-Topic abonnieren
+            client.subscribe(mqtt_command_topic);
+            // Discovery-Nachricht und initialen Status senden
+            publishDiscoveryMessage();
+            publishState();
+        } else {
+            Serial.print("Fehler, rc=");
+            Serial.print(client.state());
+            Serial.println(" -> neuer Versuch in 5s");
+            delay(5000);
+        }
+    }
+}
+
+
 // ----------------------------------- Setup Code ---------------------------------------------- //
 void setup() {
     pinMode(OutputEnable, OUTPUT);
@@ -164,10 +277,20 @@ void setup() {
     setSyncProvider(getNtpTime);
     update_counter = 0;
     init_done = true;
+
+    // <<< MQTT init >>>
+    client.setServer(mqtt_server, mqtt_port);
+    client.setCallback(mqttCallback);
 }
 
 // -------------------------------------- Main Loop ------------------------------------------------- //
 void loop() {
+    // <<< MQTT >>>
+    if (!client.connected()) {
+        reconnect();
+    }
+    client.loop();
+
     time_t timestamp = now();
     // Sync blinking with second change
     if (cur_time != timestamp && !second_changed) {
@@ -216,7 +339,7 @@ void loop() {
         shift_state = 0;
         updateDate(timestamp);
 
-        animation = rand() % 6;
+        animation = (int) (rand() % 6);
     }
 
     // Blinkenfoo - comment to remove pulsating light
@@ -233,10 +356,19 @@ void loop() {
 
 // ---------------------- Interrupt Handler (Timer1) ------------------- //
 void updateDisplay() {
+    if (!displayEnabled) {
+        // Anzeige aus: alles dunkel
+        digitalWrite(latchPin, LOW);
+        for (int digitCount = 5; digitCount >= 0; digitCount--) {
+            shiftOut(dataPin, clockPin, MSBFIRST, 0);
+        }
+        digitalWrite(latchPin, HIGH);
+        return;
+    }
+
     // take the latchPin low so
     // the LEDs don't flicker while you're sending in bits:
     digitalWrite(latchPin, LOW);
-
     for (int digitCount = 5; digitCount >= 0; digitCount--) {
         shiftOut(dataPin, clockPin, MSBFIRST, frame[digitCount]);
     }
@@ -244,7 +376,6 @@ void updateDisplay() {
     digitalWrite(latchPin, HIGH);
 
     update_counter++;
-
     if (update_counter == 1000) {
         update_counter = 0;
     }
@@ -256,6 +387,7 @@ void updateDisplay() {
     }
 }
 
+
 // -------------------------------- Date Functions ---------------------- //
 void updateDate(time_t t) {
     today[0] = digits[(day(t) / 10)];