/*

 Emulator DCF77
 Simulate a DCF77 radio receiver with a ESP8266, esp01 model
 Emit a complete three minute pulses train from the GPIO2 output
 the train is preceded by a single pulse ad the lacking 59° pulse to allow some clock model sincronization
 of the beginning frame
 after the three pulses train one more single pulse is sent to safely close the frame
 get the time from the ntp service

 Uses Time library to facilitate time computation

 
 Known issue:
 -When the DayLightSaving mode change, the three minutes packet is not checked for possible changes of hour across the frame
  itself, moreover the daylight saving is changed normally at 3 o clock in the morning (here in italy), while I don't correct for it
  so the time will be probably incorrect before at least 03:03 then dayLightSaving changes
 -the exact "second" precision is not guaranteed because of the semplicity of the NTP imnplementation
  normally the packet transit delay would be taken into account, but here is not

 Fuso68 05/12/2015

 19/12/2015 added disconnect and reconnect if wlan fail, reconnect also after three failed ntp requests
 20/12/2015 increased wlan connect timeout to 30 seconds

 
   
 Based upon:
 Udp NTP Client

 Get the time from a Network Time Protocol (NTP) time server
 Demonstrates use of UDP sendPacket and ReceivePacket
 For more on NTP time servers and the messages needed to communicate with them,
 see http://en.wikipedia.org/wiki/Network_Time_Protocol

 created 4 Sep 2010
 by Michael Margolis
 modified 9 Apr 2012
 by Tom Igoe
 updated for the ESP8266 12 Apr 2015 
 by Ivan Grokhotkov

 This code is in the public domain.

 */
#include <TimeLib.h>
#include <ESP8266WiFi.h>
#include <WiFiUdp.h>
#include <Ticker.h>



char ssid[] = "xxxx";  //  your network SSID (name)
char pass[] = "xxxx";       // your network password


unsigned int localPort = 2390;      // local port to listen for UDP packets

/* Don't hardwire the IP address or we won't get the benefits of the pool.
 *  Lookup the IP address for the host name instead */
IPAddress timeServerIP; // time.nist.gov NTP server address
const char* ntpServerName = "0.it.pool.ntp.org";

const int NTP_PACKET_SIZE = 48; // NTP time stamp is in the first 48 bytes of the message

byte packetBuffer[ NTP_PACKET_SIZE]; //buffer to hold incoming and outgoing packets

// A UDP instance to let us send and receive packets over UDP
WiFiUDP udp;

//udp reply missing counter
int UdpNoReplyCounter = 0;

//routine timer ogni 100 msec
Ticker DcfOutTimer;

#define LedPin 2

//how many total pulses we have
//three coimplete minutes + 2 head pulses and one tail pulse
#define MaxPulseNumber 183
#define FirstMinutePulseBegin 2
#define SecondMinutePulseBegin 62
#define ThirdMinutePulseBegin 122


//complete array of pulses for three minutes
//0 = no pulse, 1=100msec, 2=200msec
int ArrayImpulsi[MaxPulseNumber];

int ContaImpulsi = 0;
int UscitaDcfOn = 0;
int ContaImpulsiParziale = 0;
int Ore,Minuti,Secondi,Giorno,Mese,Anno,DayOfW;

const int timeZone = 1;     // Central European Time

int Dls;                    //DayLightSaving

void setup()
{
  Serial.begin(115200);
  Serial.println();
  Serial.println("DCF77 emulator INIT");
 
  pinMode(LedPin, OUTPUT);
  digitalWrite(LedPin, LOW);
  
  //gestione inpulsi DCF
  DcfOutTimer.attach_ms(100, DcfOut);

  //first 2 pulses: 1 + blank to simulate the packet beginning
  //il primo bit e' un 1
  ArrayImpulsi[0] = 1;
  //segue l'impulso mancante che indica il sincronismo di ricerca inizio minuto
  ArrayImpulsi[1] = 0;

  //last pulse after the third 59° blank
  ArrayImpulsi[MaxPulseNumber - 1] = 1;
  
  ContaImpulsi = 0;
  UscitaDcfOn = 0;    //we begin with the output OFF

  //we begin connecting to wifi
  //NOTE testing WiFi.status() BEFORE the FIRST WiFi.begin() seems to hang the system
  //so we attempt a first connection BEFORE the main loop
  ConnettiWifi();
}

void loop(){
  
  //check the lan status
  if (WiFi.status() == WL_CONNECTED)
     LeggiEdecodificaTempo();
  else
    ConnettiWifi();

  delay(60000);

}


void ConnettiWifi(){
  int Timeout;

  WiFi.disconnect();
  Serial.println("disconnessione !");
  delay(1000);        //necessary ???
  Serial.print("Connecting to ");
  Serial.println(ssid);
  WiFi.begin(ssid, pass);
  Timeout = 0;
  while (WiFi.status() != WL_CONNECTED) {
    delay(500);
    Serial.print(".");
    if (Timeout++ > 60){
      Serial.println("\nImpossible to connect WLAN!");
      WiFi.disconnect();
      return;
    }
  };
  Serial.println("");
  Serial.println("WiFi connected");
  Serial.println("IP address: ");
  Serial.println(WiFi.localIP());

}

void LeggiEdecodificaTempo() {

  int DayToEndOfMonth,DayOfWeekToEnd,DayOfWeekToSunday;

  //get a random server from the pool
  WiFi.hostByName(ntpServerName, timeServerIP); 

  Serial.println("Starting UDP");
  udp.begin(localPort);
  Serial.print("Local port: ");
  Serial.println(udp.localPort());

  sendNTPpacket(timeServerIP); // send an NTP packet to a time server
  // wait to see if a reply is available
  delay(1000);
  
  int cb = udp.parsePacket();
  if (!cb) {
    Serial.println("no packet yet");
    //try max 3 times (every minute) after that we force the wifi to reconnect
    if (UdpNoReplyCounter++ == 3){
      Serial.println("troppi errori di reply udp");
      ConnettiWifi();
      UdpNoReplyCounter = 0;
    };
  } else {
    UdpNoReplyCounter = 0;
    Serial.print("packet received, length=");
    Serial.println(cb);
    // We've received a packet, read the data from it
    udp.read(packetBuffer, NTP_PACKET_SIZE); // read the packet into the buffer

    //the timestamp starts at byte 40 of the received packet and is four bytes,
    // or two words, long. First, esxtract the two words:

    unsigned long highWord = word(packetBuffer[40], packetBuffer[41]);
    unsigned long lowWord = word(packetBuffer[42], packetBuffer[43]);
    // combine the four bytes (two words) into a long integer
    // this is NTP time (seconds since Jan 1 1900):
    unsigned long secsSince1900 = highWord << 16 | lowWord;
    Serial.print("Seconds since Jan 1 1900 = " );
    Serial.println(secsSince1900);

    // now convert NTP time into everyday time:
    Serial.print("Unix time = ");
    // Unix time starts on Jan 1 1970. In seconds, that's 2208988800:
    const unsigned long seventyYears = 2208988800UL;
    // subtract seventy years:
    //note: we add two minutes because the dcf protocol send the time of the FOLLOWING minute
    //and our transmissione begin the next minute more
    time_t epoch = secsSince1900 - seventyYears + ( timeZone * 3600 ) + 120;
    // print Unix time:
    Serial.println(epoch);

    //calculate actual day to evaluate the summer/winter time of day ligh saving
    DayOfW = weekday(epoch);
    Giorno = day(epoch);
    Mese = month(epoch);
    Anno = year(epoch);
    Serial.print("Tempo Locale ");       // UTC is the time at Greenwich Meridian (GMT)
    Serial.print(Giorno);
    Serial.print('/');
    Serial.print(Mese);
    Serial.print('/');
    Serial.print(Anno);
    Serial.print(' ');
  
    //calcolo ora solare o legale
    Dls = 0;    //default winter time
    //From April to september we are surely on summer time
    if (Mese > 3 && Mese < 10) {
      Dls = 1;
    };
    //March, month of change winter->summer time, last last sunday of the month
    //March has 31days so from 25 included on sunday we can be in summer time
    if (Mese == 3 && Giorno > 24) {
      DayToEndOfMonth = 31 - Giorno;
      DayOfWeekToSunday = 7 - DayOfW;
      if (DayOfWeekToSunday >= DayToEndOfMonth)
        Dls = 1;
    };
    //Octobee, month of change summer->winter time, l'ultima Domenica del mese
    //Even Octobee has 31days so from 25 included on sunday we can be in winter time
    if (Mese == 10) {
      Dls = 1;
      if (Giorno > 24) {
        DayToEndOfMonth = 31 - Giorno;
        DayOfWeekToEnd = 7 - DayOfW;
        if (DayOfWeekToEnd >= DayToEndOfMonth)
        Dls = 0;
      };
    };

    Serial.print("Dls:");
    Serial.print(Dls);
    Serial.print(' ');
    //add one hour if we are in summer time
    if (Dls == 1)
      epoch += 3600;

    //now that we know the dls state, we can calculate the time too
    // print the hour, minute and second:
    Ore = hour(epoch);
    Minuti = minute(epoch);
    Secondi = second(epoch);
    Serial.print(Ore); // print the hour
    Serial.print(':');
    Serial.print(Minuti); // print the minute
    Serial.print(':');
    Serial.println(Secondi); // print the second

    //if we are over about the 56° second we risk to begin the pulses too late, so it's better
    //to skit at the half of the next minute and NTP+recalculate all again
    if (Secondi > 56){
      delay(30000);
      return;      
    }

    //calculate bits array for the first minute
    CalcolaArray(FirstMinutePulseBegin);

    //add one minute ad calculate array again fot the second minute
    epoch += 60;
    DayOfW = weekday(epoch);
    Giorno = day(epoch);
    Mese = month(epoch);
    Anno = year(epoch);
    Ore = hour(epoch);
    Minuti = minute(epoch);
    Secondi = second(epoch);
    CalcolaArray(SecondMinutePulseBegin);

    //one minute more for the third minute
    epoch += 60;
    DayOfW = weekday(epoch);
    Giorno = day(epoch);
    Mese = month(epoch);
    Anno = year(epoch);
    Ore = hour(epoch);
    Minuti = minute(epoch);
    Secondi = second(epoch);
    CalcolaArray(ThirdMinutePulseBegin);

   
    //how many to the minute end ?
    //don't forget that we begin transmission at second 58°
    int DaPerdere = 58 - Secondi;
    delay(DaPerdere * 1000);
    //begin
    UscitaDcfOn = 1;

    //three minutes are needed to transmit all the packet
    //then wait more 30 secs to locate safely at the half of minute
    //NB 150+60=210sec, 60secs are lost from main routine
    delay(150000);

  };

  udp.stop() ;

}





void CalcolaArray(int ArrayOffset) {
  int n,Tmp,TmpIn;
  int ParityCount = 0;

  //i primi 20 bits di ogni minuto li mettiamo a valore logico zero
  for (n=0;n<20;n++)
    ArrayImpulsi[n+ArrayOffset] = 1;

  //DayLightSaving bit
  if (Dls == 1)
    ArrayImpulsi[17+ArrayOffset] == 2;
  else
    ArrayImpulsi[18+ArrayOffset] == 2;
    
  //il bit 20 deve essere 1 per indicare tempo attivo
  ArrayImpulsi[20+ArrayOffset] = 2;

  //calcola i bits per il minuto
  TmpIn = Bin2Bcd(Minuti);
  for (n=21;n<28;n++) {
    Tmp = TmpIn & 1;
    ArrayImpulsi[n+ArrayOffset] = Tmp + 1;
    ParityCount += Tmp;
    TmpIn >>= 1;
  };
  if ((ParityCount & 1) == 0)
    ArrayImpulsi[28+ArrayOffset] = 1;
  else
    ArrayImpulsi[28+ArrayOffset] = 2;

  //calcola i bits per le ore
  ParityCount = 0;
  TmpIn = Bin2Bcd(Ore);
  for (n=29;n<35;n++) {
    Tmp = TmpIn & 1;
    ArrayImpulsi[n+ArrayOffset] = Tmp + 1;
    ParityCount += Tmp;
    TmpIn >>= 1;
  }
  if ((ParityCount & 1) == 0)
    ArrayImpulsi[35+ArrayOffset] = 1;
  else
    ArrayImpulsi[35+ArrayOffset] = 2;
   ParityCount = 0;
  //calcola i bits per il giorno
  TmpIn = Bin2Bcd(Giorno);
  for (n=36;n<42;n++) {
    Tmp = TmpIn & 1;
    ArrayImpulsi[n+ArrayOffset] = Tmp + 1;
    ParityCount += Tmp;
    TmpIn >>= 1;
  }
  //calcola i bits per il giorno della settimana
  TmpIn = Bin2Bcd(DayOfW);
  for (n=42;n<45;n++) {
    Tmp = TmpIn & 1;
    ArrayImpulsi[n+ArrayOffset] = Tmp + 1;
    ParityCount += Tmp;
    TmpIn >>= 1;
  }
  //calcola i bits per il mese
  TmpIn = Bin2Bcd(Mese);
  for (n=45;n<50;n++) {
    Tmp = TmpIn & 1;
    ArrayImpulsi[n+ArrayOffset] = Tmp + 1;
    ParityCount += Tmp;
    TmpIn >>= 1;
  }
  //calcola i bits per l'anno
  TmpIn = Bin2Bcd(Anno - 2000);   //a noi interesa solo l'anno con ... il millenniumbug !
  for (n=50;n<58;n++) {
    Tmp = TmpIn & 1;
    ArrayImpulsi[n+ArrayOffset] = Tmp + 1;
    ParityCount += Tmp;
    TmpIn >>= 1;
  }
  //parita' di data
  if ((ParityCount & 1) == 0)
    ArrayImpulsi[58+ArrayOffset] = 1;
  else
    ArrayImpulsi[58+ArrayOffset] = 2;

  //ultimo impulso mancante
  ArrayImpulsi[59+ArrayOffset] = 0;

  /* for debug: print the whole 180 secs array
   * Serial.print(':');
  for (n=0;n<60;n++)
    Serial.print(ArrayImpulsi[n+ArrayOffset]);*/

}


// send an NTP request to the time server at the given address
unsigned long sendNTPpacket(IPAddress& address)
{
  Serial.println("sending NTP packet...");
  // set all bytes in the buffer to 0
  memset(packetBuffer, 0, NTP_PACKET_SIZE);
  // Initialize values needed to form NTP request
  // (see URL above for details on the packets)
  packetBuffer[0] = 0b11100011;   // LI, Version, Mode
  packetBuffer[1] = 0;     // Stratum, or type of clock
  packetBuffer[2] = 6;     // Polling Interval
  packetBuffer[3] = 0xEC;  // Peer Clock Precision
  // 8 bytes of zero for Root Delay & Root Dispersion
  packetBuffer[12]  = 49;
  packetBuffer[13]  = 0x4E;
  packetBuffer[14]  = 49;
  packetBuffer[15]  = 52;

  // all NTP fields have been given values, now
  // you can send a packet requesting a timestamp:
  udp.beginPacket(address, 123); //NTP requests are to port 123
  udp.write(packetBuffer, NTP_PACKET_SIZE);
  udp.endPacket();
}


//richiamata ciclicamente ogni 100msec
//per uscita di simulazione DFC77
void DcfOut() {

  if (UscitaDcfOn == 1) {
    switch (ContaImpulsiParziale++) {
      case 0:
        if (ArrayImpulsi[ContaImpulsi] != 0)
          digitalWrite(LedPin, 1);
        break;
      case 1:
        if (ArrayImpulsi[ContaImpulsi] == 1)
          digitalWrite(LedPin, 0);
        break;
      case 2:
        digitalWrite(LedPin, 0);
        break;
      case 9:
        if (ContaImpulsi++ == (MaxPulseNumber -1 )){     //one less because we FIRST tx the pulse THEN count it
          ContaImpulsi = 0;
          UscitaDcfOn = 0;
        };
        ContaImpulsiParziale = 0;
        break;
    };
  };

}

int Bin2Bcd(int dato) {
  int msb,lsb;

  if (dato < 10)
    return dato;
  msb = (dato / 10) << 4;
  lsb = dato % 10; 
  return msb + lsb;
}