/*   Programm zum DCF77 Empfang für atmega 328p
     Sekunden Timer ISR
     5 Volt Variante für Peripherie
     Datenempfang vom Coprozessor
     19.05.2025
*/

#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 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;

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);
  delay(100);

  // 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;

    /***********************************************************************

      Die einzelnen Ziffern der vier Variablen werden in
      dekadische Zahlen umgewandelt, damit sie vom lokalen
      Minutentakt weiter gezählt werden können

    ***********************************************************************/
    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;
      }
    }
    /***********************************************************************

      zerlegt die dekadische Zahl wieder in einzelne Ziffern
      für die Anzeige

     **********************************************************************/

    einerStunden = noSignalStundenCounter % 10;
    zehnerStunden = (noSignalStundenCounter / 10) % 10;
    einerMinuten = noSignalMinutenCounter % 10;
    zehnerMinuten = (noSignalMinutenCounter / 10) % 10;
  }
}

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()) {
    zehnerStunden = Serial.parseInt();
    einerStunden = Serial.parseInt();
    zehnerMinuten = Serial.parseInt();
    einerMinuten = Serial.parseInt();
    String(DCFzeit) = Serial.readString();

  }

  initDisplay();                  // zeigt die Uhrzeit an

}