diff --git a/Coprozessor_DCF77.ino b/Coprozessor_DCF77.ino
new file mode 100644
index 0000000..a6f6550
--- /dev/null
+++ b/Coprozessor_DCF77.ino
@@ -0,0 +1,145 @@
+/*  Das Programm dekodiert die DCF77 Zeit,
+    macht die Paritätsprüfung und
+    schickt die vier benötigten Ziffern für die Zeitanzeige
+    als serielle Daten über den TX Pin 1 an den Anzeigecontroller.
+    Datengeschwindigkeit: 9600 Baud
+    Wenn ein gültiges Signal gesendet wurde, gibt es eine Pause von 30 Minuten,
+    in dieser Zeit wird der DCF Empfänger an Pin 6 abgeschaltet.
+    mit Hilfe von: https://wolles-elektronikkiste.de/dcf77-funkuhr
+    30.04.2025
+*/
+
+#include <util/parity.h> //comment out if you don't use an AVR MCU
+
+#define dcfOnOut 6
+int interruptPin = 2;
+
+volatile unsigned long lastInt = 0;
+volatile unsigned long long currentBuf = 0;
+volatile byte bufCounter;
+volatile bool parityStat = 0;
+volatile byte dcf77MinuteEiner = 0;
+volatile byte dcf77MinuteZehner = 0;
+volatile byte dcf77HourEiner = 0;
+volatile byte dcf77HourZehner = 0;
+
+
+void setup() {
+  Serial.begin(9600);
+  pinMode(dcfOnOut, OUTPUT);
+  digitalWrite(dcfOnOut, HIGH);
+  pinMode(interruptPin, INPUT);
+  attachInterrupt(digitalPinToInterrupt(interruptPin), DCF77_ISR, CHANGE);
+}
+
+void loop() {
+  if (parityStat == 1) {
+    delay(100);
+    Serial.print(dcf77HourZehner);
+    Serial.print(",");
+    Serial.print(dcf77HourEiner);
+    Serial.print(",");
+    Serial.print(dcf77MinuteZehner);
+    Serial.print(",");
+    Serial.print(dcf77MinuteEiner);
+    delay(100);
+
+    digitalWrite(dcfOnOut, LOW);
+
+    parityStat = 0;
+    delay(1800000);   // 30 Minuten, 15 Minuten Wartezeit: 900000
+    digitalWrite(dcfOnOut, HIGH);
+  }
+}
+
+/*************************************************************************
+
+       lesen des dcf Signals am Pin 2
+
+**************************************************************************/
+
+void DCF77_ISR() {                       //
+  unsigned int dur = 0;
+  dur = millis() - lastInt;
+
+  if (digitalRead(interruptPin)) {
+
+    if (dur > 1500) {
+      unsigned long highBuf = (currentBuf >> 32) & 0x7FFFFFF;
+      unsigned long lowBuf = (currentBuf & 0xFFFFFFFF);
+      bufCounter = 0;
+
+      evaluateSequence();
+      currentBuf = 0;
+    }
+  }
+  else {
+    if (dur > 150) {
+      currentBuf |= ((unsigned long long)1 << bufCounter);
+    }
+    bufCounter++;
+  }
+  lastInt = millis();
+}
+
+/**************************************************************************
+
+             Umwandlung Binärcode in Ziffern
+
+ *************************************************************************/
+
+
+void evaluateSequence() {
+  parityStat = 1;
+  byte dcf77Year = (currentBuf >> 50) & 0xFF;  // year = bit 50-57
+  byte dcf77Month = (currentBuf >> 45) & 0x1F;     // month = bit 45-49
+  byte dcf77DayOfWeek = (currentBuf >> 42) & 0x07; // day of the week = bit 42-44
+  byte dcf77DayOfMonth = (currentBuf >> 36) & 0x3F; // day of the month = bit 36-41
+  byte dcf77Hour = (currentBuf >> 29) & 0x3F;
+  dcf77HourEiner = (currentBuf >> 29) & 0xF;     // hour = bit 29-34, 6 bit
+  dcf77HourZehner = (currentBuf >> 33) & 0x3;     // hour = bit 29-34, 6 bit
+  byte dcf77Minute = (currentBuf >> 21) & 0x7F;
+  dcf77MinuteEiner = (currentBuf >> 21) & 0xF;   // minute = 21-27, 7 bit
+  dcf77MinuteZehner = (currentBuf >> 25) & 0x7;   // minute = 21-27, 7 bit
+
+  bool parityBitMinute = (currentBuf >> 28) & 1;
+  bool parityBitHour = (currentBuf >> 35) & 1;
+  bool parityBitDate = (currentBuf >> 58) & 1;
+
+  /***************************************************************************
+                     Paritätsprüfung
+
+  ***************************************************************************/
+
+  if ((parity_even_bit(dcf77Minute)) != parityBitMinute) {
+    parityStat = 0;
+  }
+  if ((parity_even_bit(dcf77Hour)) != parityBitHour) {
+    parityStat = 0;
+  }
+  if (((parity_even_bit(dcf77DayOfMonth) + parity_even_bit(dcf77DayOfWeek)
+        + parity_even_bit(dcf77Month) + parity_even_bit(dcf77Year)) % 2) != parityBitDate)
+  {
+    parityStat = 0;
+  }
+  if (dcf77MinuteEiner > 9) {
+    parityStat = 0;
+  }
+  if (dcf77MinuteZehner > 5) {
+    parityStat = 0;
+  }
+  if (dcf77HourEiner > 9) {
+    parityStat = 0;
+  }
+  if (dcf77HourZehner > 2) {
+    parityStat = 0;
+  }
+  if (dcf77Hour == 0 && dcf77Minute == 0) {
+    parityStat = 0;
+  }
+
+}
+
+unsigned int rawByteToInt(byte raw) {
+  return ((raw >> 4) * 10 + (raw & 0x0F));
+}
diff --git a/Uhr_DCF77_5Volt_V3.ino b/Uhr_DCF77_5Volt_V3.ino
new file mode 100644
index 0000000..a783a6b
--- /dev/null
+++ b/Uhr_DCF77_5Volt_V3.ino
@@ -0,0 +1,333 @@
+/*   Programm zum DCF77 Empfang für atmega 328p
+     Sekunden Timer ISR
+     5 Volt Variante für Peripherie
+     Datenempfang vom Coprozessor
+     03.05.2025
+*/
+
+#define bcdA 5                      // D5
+#define bcdB 6                      // D6
+#define bcdC 7                      // D7
+#define bcdD 8                      // D8
+#define displayPosition1 9          // D9
+#define displayPosition2 10         // D10
+#define displayPosition3 3          // D3
+#define displayPosition4 4          // D4
+
+byte selectZiffer = 0;
+byte displayPosition = 0;
+volatile int dcf77MinuteEiner = 0;
+volatile int dcf77MinuteZehner = 0;
+volatile int dcf77HourEiner = 0;
+volatile int dcf77HourZehner = 0;
+volatile byte noSignalMinutenCounter = 0;
+volatile byte noSignalStundenCounter = 0;
+volatile byte einerStunden = 7;
+volatile byte zehnerStunden = 1;
+volatile byte einerMinuten = 0;
+volatile byte zehnerMinuten = 1;
+volatile byte offlineCounter = 0;
+volatile bool parityStat = 0;
+
+void setup() {
+  pinMode(bcdA, OUTPUT);
+  pinMode(bcdB, OUTPUT);
+  pinMode(bcdC, OUTPUT);
+  pinMode(bcdD, OUTPUT);
+  pinMode(displayPosition1, OUTPUT);
+  pinMode(displayPosition2, OUTPUT);
+  pinMode(displayPosition3, OUTPUT);
+  pinMode(displayPosition4, OUTPUT);
+  
+
+  digitalWrite(bcdA, HIGH);
+  digitalWrite(bcdB, HIGH);
+  digitalWrite(bcdC, HIGH);
+  digitalWrite(bcdD, HIGH);
+  digitalWrite(displayPosition1, HIGH);
+  digitalWrite(displayPosition2, HIGH);
+  digitalWrite(displayPosition3, HIGH);
+  digitalWrite(displayPosition4, HIGH);
+  
+  Serial.begin(9600);
+
+  // Timer1 setzen (1 Sekunde = 49911, zwei Sekunden = 34286)
+  TCCR1A = 0x00;
+  TCCR1B = (1<<CS12) | (1<<CS10);
+  TIMSK1 = (1<<TOIE1);
+  TCNT1 = 49911;
+  
+}
+
+ISR(TIMER1_OVF_vect){
+  
+  TCNT1 = 49911;
+  offlineCounter++;
+  
+  if (offlineCounter > 59){
+    
+    offlineCounter = 0;
+
+    if (parityStat == 0) {
+      byte m = zehnerMinuten * 10;
+      noSignalMinutenCounter = m + einerMinuten;
+      byte s = zehnerStunden * 10;
+      noSignalStundenCounter = s + einerStunden;
+
+      noSignalMinutenCounter++;
+
+      if (noSignalMinutenCounter > 59) {
+          noSignalMinutenCounter = 0;
+          noSignalStundenCounter++;
+          if (noSignalStundenCounter > 23) {
+            noSignalStundenCounter = 0;
+        }
+      }
+      einerStunden = noSignalStundenCounter % 10;                // zerlegt die Zahl in Einer
+      zehnerStunden = (noSignalStundenCounter / 10) % 10;        // und Zehner
+      einerMinuten = noSignalMinutenCounter % 10;
+      zehnerMinuten = (noSignalMinutenCounter / 10) % 10;
+    }
+
+    else {
+      einerMinuten = dcf77MinuteEiner;
+      zehnerMinuten = dcf77MinuteZehner;
+      einerStunden = dcf77HourEiner;
+      zehnerStunden = dcf77HourZehner;
+      parityStat = 0;
+    }   
+  }
+}
+
+void initDisplay() {
+
+  // Die Schleife ruft nacheinander die Anzeigestellen auf und übergibt die Ziffern
+
+  for (displayPosition = 1; displayPosition <= 4; displayPosition++) {
+
+    if (displayPosition == 1) {
+      digitalWrite(displayPosition1, HIGH);
+      digitalWrite(displayPosition2, LOW);
+      digitalWrite(displayPosition3, LOW);
+      digitalWrite(displayPosition4, LOW); 
+
+      if (zehnerStunden == 0) {
+        selectZiffer = 0;
+      }
+      if (zehnerStunden == 1) {
+        selectZiffer = 1;
+      }
+      if (zehnerStunden == 2) {
+        selectZiffer = 2;
+      }
+    }
+
+    if (displayPosition == 2) {
+      digitalWrite(displayPosition1, LOW);
+      digitalWrite(displayPosition2, HIGH);
+      digitalWrite(displayPosition3, LOW);
+      digitalWrite(displayPosition4, LOW); 
+
+      if (einerStunden == 0) {
+        selectZiffer = 0;
+      }
+      if (einerStunden == 1) {
+        selectZiffer = 1;
+      }
+      if (einerStunden == 2) {
+        selectZiffer = 2;
+      }
+      if (einerStunden == 3) {
+        selectZiffer = 3;
+      }
+      if (einerStunden == 4) {
+        selectZiffer = 4;
+      }
+      if (einerStunden == 5) {
+        selectZiffer = 5;
+      }
+      if (einerStunden == 6) {
+        selectZiffer = 6;
+      }
+      if (einerStunden == 7) {
+        selectZiffer = 7;
+      }
+      if (einerStunden == 8) {
+        selectZiffer = 8;
+      }
+      if (einerStunden == 9) {
+        selectZiffer = 9;
+      }
+    }
+
+    if (displayPosition == 3) {
+      digitalWrite(displayPosition1, LOW);
+      digitalWrite(displayPosition2, LOW);
+      digitalWrite(displayPosition3, HIGH);
+      digitalWrite(displayPosition4, LOW); 
+
+      
+      if (zehnerMinuten == 0) {
+        selectZiffer = 0;
+      }
+      if (zehnerMinuten == 1) {
+        selectZiffer = 1;
+      }
+      if (zehnerMinuten == 2) {
+        selectZiffer = 2;
+      }
+      if (zehnerMinuten == 3) {
+        selectZiffer = 3;
+      }
+      if (zehnerMinuten == 4) {
+        selectZiffer = 4;
+      }
+      if (zehnerMinuten == 5) {
+        selectZiffer = 5;
+      }
+
+    }
+
+    if (displayPosition == 4) {
+      digitalWrite(displayPosition1, LOW);
+      digitalWrite(displayPosition2, LOW);
+      digitalWrite(displayPosition3, LOW);
+      digitalWrite(displayPosition4, HIGH); 
+
+      
+      if (einerMinuten == 0) {
+        selectZiffer = 0;
+      }
+      if (einerMinuten == 1) {
+        selectZiffer = 1;
+      }
+      if (einerMinuten == 2) {
+        selectZiffer = 2;
+      }
+      if (einerMinuten == 3) {
+        selectZiffer = 3;
+      }
+      if (einerMinuten == 4) {
+        selectZiffer = 4;
+      }
+      if (einerMinuten == 5) {
+        selectZiffer = 5;
+      }
+      if (einerMinuten == 6) {
+        selectZiffer = 6;
+      }
+      if (einerMinuten == 7) {
+        selectZiffer = 7;
+      }
+      if (einerMinuten == 8) {
+        selectZiffer = 8;
+      }
+      if (einerMinuten == 9) {
+        selectZiffer = 9;
+      }
+    }
+
+    // BCD Zifferncode
+
+    switch (selectZiffer) {
+      case 0:
+        digitalWrite(bcdA, LOW);
+        digitalWrite(bcdB, LOW);
+        digitalWrite(bcdC, LOW);
+        digitalWrite(bcdD, LOW);
+        break;
+
+      case 1:
+        digitalWrite(bcdA, HIGH);
+        digitalWrite(bcdB, LOW);
+        digitalWrite(bcdC, LOW);
+        digitalWrite(bcdD, LOW);
+        break;
+
+      case 2:
+        digitalWrite(bcdA, LOW);
+        digitalWrite(bcdB, HIGH);
+        digitalWrite(bcdC, LOW);
+        digitalWrite(bcdD, LOW);
+        break;
+
+      case 3:
+        digitalWrite(bcdA, HIGH);
+        digitalWrite(bcdB, HIGH);
+        digitalWrite(bcdC, LOW);
+        digitalWrite(bcdD, LOW);
+        break;
+
+      case 4:
+        digitalWrite(bcdA, LOW);
+        digitalWrite(bcdB, LOW);
+        digitalWrite(bcdC, HIGH);
+        digitalWrite(bcdD, LOW);
+        break;
+
+      case 5:
+        digitalWrite(bcdA, HIGH);
+        digitalWrite(bcdB, LOW);
+        digitalWrite(bcdC, HIGH);
+        digitalWrite(bcdD, LOW);
+        break;
+
+      case 6:
+        digitalWrite(bcdA, LOW);
+        digitalWrite(bcdB, HIGH);
+        digitalWrite(bcdC, HIGH);
+        digitalWrite(bcdD, LOW);
+        break;
+
+      case 7:
+        digitalWrite(bcdA, HIGH);
+        digitalWrite(bcdB, HIGH);
+        digitalWrite(bcdC, HIGH);
+        digitalWrite(bcdD, LOW);
+        break;
+
+      case 8:
+        digitalWrite(bcdA, LOW);
+        digitalWrite(bcdB, LOW);
+        digitalWrite(bcdC, LOW);
+        digitalWrite(bcdD, HIGH);
+        break;
+
+      case 9:
+        digitalWrite(bcdA, HIGH);
+        digitalWrite(bcdB, LOW);
+        digitalWrite(bcdC, LOW);
+        digitalWrite(bcdD, HIGH);
+        break;
+
+    }
+
+    // Unterdrueckung der fuehrenden Null
+
+    if (displayPosition == 1) {
+      if (selectZiffer == 0) {
+        goto noTime;
+      }
+    }
+
+    delayMicroseconds(2500);                //Anschaltzeit der Ziffern
+
+noTime: {}
+
+  }
+}
+
+void loop() {
+  if (Serial.available()){
+    dcf77HourZehner = Serial.parseInt();
+    dcf77HourEiner = Serial.parseInt();
+    dcf77MinuteZehner = Serial.parseInt();
+    dcf77MinuteEiner = Serial.parseInt();
+    String(DCFzeit) = Serial.readString();
+      
+    parityStat = 1;    
+  }
+ 
+  initDisplay();                  // zeigt die Uhrzeit an
+  
+}