Най-доброто управление на термопомпа въздух-вода 23 мнения

[2v6]

Как да стане?

По-късно ще покажа моите идеи с цел някой да не си помисли, че това е най-доброто

Най-доброто е някаква оптимална комбинация от хардуер и софтуер.
Един от факторите е цената - най-евтиния и най-скъпия контролер не са най-доброто решение.

[denuchi]

Мисля да пробвам с това.: http://il106247218.trustpass.alibaba.co ... &edm_ver=e
Сравнително ниска цена, софтуер от теб. Както си поискаш и каквото си поискаш. Триеш софтуера и на ново докато ти хареса.
А като цена 270 лв. Напълно нормална и поносима цена, според мен.

[a_stoev]

Вземи си един MCX на Данфос, бившите некос. Вече има FBD програмиране - редиш блокчета и свързваш с мишката. Сензорите му са NTC 10k, 12лв. 10-годишно дете може да се оправи с него. Ако ти е труден има и готови програми.
Тоя SuperBrain DR не ми харесва заради това че няма NTC на аналоговия вход. Има лан порт, но надали ще ти трябва. И е еврейски. От еврейска автоматика имам само лоши спомени. Пък и не видях дали е свободно програмируем. Само набор програми за климатични камери.

[2v6]

Първо да уточним схемата:

Прикачен файл:

AWHP basic diagram.JPG (26.39 KиБ) Видяна 9125 пъти

1 - Вентилатор
2 - Топлообменник въздух-фреон
3 - Дросел (капилярка или ТРВ)
4 - Компресор
5 - 4-пътен вентил
6 - Топлообменник фреон вода
7 - Водна циркулационна помпа
8 - Датчик поток
Т1 - Температура вода вход топлообменник
Т2 - Температура вода изход топлообменник
Т3 - Температура фреон течна фаза към/от топлообменник фреон-вода
Т4 - Температура топлообменник въздух-фреон
Т5 - Температра външен въздух

[denuchi]

Аз бих добавил и два филтъра в този си вариант. И още малко от мен два датчика температурни и два датчика за налягане.

[dj666]

Извинявай, тази схема не съм я правил аз само съм я допълнил. Не е ли по правилно да хванеш топлообменника преди 4-пътния вентил, ако някой ден решиш да сложиш и вътрешно тяло (конвертор) за охлаждане???

[denuchi]

Не.

[2v6]

Аз бих добавил и два филтъра в този си вариант. И още малко от мен два датчика температурни и два датчика за налягане.

Добавих на схемата и тези измервания.
Филтри, кранчета и други, ако са необходими за управлението може да ги добавим по-нататък...

Прикачен файл:

AWHP basic diagram.JPG (21.7 KиБ) Видяна 8924 пъти

1 - Вентилатор
2 - Топлообменник въздух-фреон
3 - Дросел (капилярка или ТРВ)
4 - Компресор
5 - 4-пътен вентил
6 - Топлообменник фреон вода
7 - Водна циркулационна помпа
8 - Датчик поток
Т1 - Температура вода вход топлообменник
Т2 - Температура вода изход топлообменник
Т3 - Температура фреон течна фаза към/от топлообменник фреон-вода
Т4 - Температура топлообменник въздух-фреон
Т5 - Температура външен въздух
Т6 - Температура фреон вход компресор
Т7 - Температура фреон изход компресор
P1 - Налягане фреон вход компресор
P2 - Налягане фреон изход компресор

[2v6]

Това е примерна схема на клемите за връзка на контролера с:
XT1 - Температура 1
XT2 - Температура 2
XT3 - Температура 3
XT4 - Температура 4
XT5 - Температура 5
XT6 - Температура 6
XT7 - Температура 7
XT8 - Температура 8
XC - Компресор
XF - Вентилатор
XV - 4-пътен вентил
XP - Циркулационна помпа
XP1 - Налягане 1
XP2 - Налягане 2

Прикачен файл:

Controller black box.GIF (7.86 KиБ) Видяна 8832 пъти

[2v6]

Започнах тест на нова версия контролер с Ардуино.
Ще работи с три сензора за температура:
За температурата на външния въздух:

Прикачен файл:

За температурата на топлообменника въздух-фреон (външната "пита"):

Прикачен файл:

За температурата на топлообменника фреон-вода:

Прикачен файл:

С кода по-долу се тества в момента.
Тук се наблюдават записите:
https://personal.xively.com/feeds/1575600701

Код: Избери всички

#define codeVersion "codeVersion: 1575600701 31.10.2016 "
#define compilationDate __DATE__
#define compilationTime __TIME__
#define lowTemperatureLimit 34 // Condenser temperature setpoint for start
#define highTemperatureLimit 44 // Condenser temperature setpoint for stop
#define defrostStartTemperature 10 // Defrost limit for T61-T62
#define defrostEndtTemperature 15 // Defrost limit for T62
#define minRunTime 1200000 // 1200 s
#define checkDefrostTime 1800000 // 2400 s
#define minDefrostTime 60000 // 60 s
#define maxDefrostTime 300000 // 300 s
#define hotDefrostTime 3000000 // 50 min
#define modeDelay 60000 // 60 s
#define afterOverheatTimeH 3000000 // 50 min
#define afterOverheatTimeL 1800000 // 30 min
#define pinT61 26 //Ambient air temperature pin
#define pinT62 30 //Evaporator temperature pin
#define pinT63 34 //Condensator temperature pin
#define pinCompressor 48
#define pinFan 46
#define pinPump 44
#define pinHeater 42
#define pinSwitch 40
#define feedTime 30000 //Time interval for sending data to Xively, ms
#define sensorsTime 10000 //Time interval for reading sensors, ms

#include <Time.h>
#include <SPI.h>
#include <Ethernet.h>
#include <EthernetUdp.h>
#include <OneWire.h>
#include <HttpClient.h>
#include <Xively.h>
#include <EEPROM.h>
#include "EEPROMAnything.h"
#include <MsTimer2.h>


byte mac[] = { 0x90, 0xA2, 0xDA, 0x00, 0x42, 0x3B };
byte ip[] = { 192,168,0, 3 };
byte gateway[] = {192,168,0,1};	
byte subnet[] = { 255, 255, 255, 0 };

//Berlin, Germany: Technische Universitaet Berlin
//130.149.17.21: ntps1-0.cs.tu-berlin.de
//130.149.17.8: ntps1-1.cs.tu-berlin.de
//132, 163, 4, 101 time-a.timefreq.bldrdoc.gov
IPAddress timeServer(130,149,17,21); 
const int timeZone = 2;     // East European Time
EthernetUDP Udp;
unsigned int localPort = 8888;  // local port to listen for UDP packets

// Your Xively key to let you upload data
char xivelyKey[] = "update key";

// Define the strings for our datastream IDs
XivelyDatastream datastreams[] = 
{
  XivelyDatastream("0", 1, DATASTREAM_FLOAT), //Ambient air temperature
  XivelyDatastream("1", 1, DATASTREAM_FLOAT), //Evaporator temperature
  XivelyDatastream("2", 1, DATASTREAM_FLOAT), //Condenser temperature
  XivelyDatastream("3", 1, DATASTREAM_FLOAT), //
  XivelyDatastream("4", 1, DATASTREAM_FLOAT), //
  XivelyDatastream("5", 1, DATASTREAM_FLOAT), //
  XivelyDatastream("6", 1, DATASTREAM_FLOAT), //
  XivelyDatastream("7", 1, DATASTREAM_FLOAT), // 
  XivelyDatastream("8", 1, DATASTREAM_FLOAT), // 
  XivelyDatastream("9", 1, DATASTREAM_FLOAT)
};

#define datastreamsNumber 10

// Finally, wrap the datastreams into a feed
XivelyFeed feed(1575600701, datastreams, datastreamsNumber);



float T61,T62,T63,T64,T65,T66,F,P,P1, PulsePeriod,Q61,Q61f=0,Q62,Q62f=0,temp_f, Tfl[10];
long loopTime, readSensors_time, sendTime, eepromTime,sendTimeInterval, recirculationTime;   
int ret,i,imp1,imp2;
byte data[12];
float datastreamTemp[datastreamsNumber], datastreamNew[datastreamsNumber], datastreamUpdated[datastreamsNumber];
bool newData, switchOn;

volatile long lastFlowPulseTime;
int mode=0;
long FlowPulseTime, SensorsReadTime, Q62Time, modeTime, TflTime;

EthernetClient client;
XivelyClient xivelyclient(client);

// initialize the library instance:
EthernetServer webserver(80);

void setup() 
{
  Serial.begin(9600);
  Serial.println(codeVersion);
  Serial.print("Compilation date: ");
  Serial.println(compilationDate);
  Serial.print("Compilation time: ");
  Serial.println(compilationTime);
  Serial.print("IP:");
  Serial.print(ip[0]);
  Serial.print(".");
  Serial.print(ip[1]);
  Serial.print(".");
  Serial.print(ip[2]);
  Serial.print(".");
  Serial.println(ip[3]);
  Ethernet.begin(mac, ip);
  delay(1000);

  startConversion(pinT61); //Ambient air temperature
  startConversion(pinT62); //Evaporator temperature
  startConversion(pinT63); //Condenser temperature
//  attachInterrupt(2, Pulse1, FALLING); // Pulse on pin21 for MEGA2560, xively ID 4,
//  attachInterrupt(3, Pulse2, FALLING); // Pulse on pin22 for MEGA2560, xively ID 7,
  //pinMode(21, INPUT);
  //digitalWrite(21, HIGH);
  //pinMode(22, INPUT);
  //digitalWrite(22, HIGH);
  delay(1000);
  Udp.begin(localPort);
  Serial.println("getNtpTime");
  setSyncProvider(getNtpTime);
  webserver.begin();
  digitalClockDisplay();  
  imp1=0;
  imp2=0;
  MsTimer2::set(9982, every_10_seconds);
  MsTimer2::start();
  digitalWrite(pinCompressor, 1);
  pinMode(pinCompressor, OUTPUT); 
  digitalWrite(pinFan, 1); 
  pinMode(pinFan, OUTPUT);
  digitalWrite(pinPump, HIGH);
  pinMode(pinPump, OUTPUT);
  digitalWrite(pinHeater, HIGH);
  pinMode(pinHeater, OUTPUT);
  Serial.print("T61: ");
  Serial.println(readSensor(pinT61));
  Serial.print("T62: ");
  Serial.println(readSensor(pinT62));
  Serial.print("T63: ");
  Serial.println(readSensor(pinT63));
}

void Pulse1()
{
  imp1++;
}

void Pulse2()
{
  imp2++;
}

void every_10_seconds() 
{
  P1=analogRead(2)/200.0;
  temp_f=Q61f;
  Q61f=temp_f+P1/360;
  sensorsRead();
  if (loopTime-TflTime>60000)
  {
    TflTime=loopTime;
    for ( i=0 ; i<9 ; i++ ) Tfl[i]=Tfl[i+1];
    Tfl[9]=T65;
  }    
}

void loop()
{
  loopTime=millis();

  sensorsRead();
  flowCalculation(); 
  controlOutput();
  sendData();
  webServer();
}

void controlOutput()
{
  if (!switchOn && mode!=0 && mode<70) mode=70;
    
  if (P1>4.5) // Compressor overload
  {
        compressorOff(); // Stop compressor
        modeTime=loopTime;
        mode=40;
  }

  switch ( mode ) 
    {
    case 0 : //Standby
      if (switchOn && loopTime-modeTime>modeDelay)
      {
        pumpOn(); // Start circulation pump
        modeTime=loopTime;
        mode=1;
      }
      break;
      
    case 1 : //Circulation on && temperature high
      if (T63<lowTemperatureLimit  && loopTime-modeTime>modeDelay)
      {
        compressorOn(); // Start compressor
        fanOn(); // Start fan & 4-way valve
        modeTime=loopTime;
        mode=9;
      }
      break;

    case 9 : //Heating minimum time
      if (loopTime-modeTime>minRunTime  && loopTime-modeTime>modeDelay)
      {
        modeTime=loopTime;
        mode=10;
      }
      break;

    case 10 : //Heating
      if (T63>highTemperatureLimit) // Stop heating 
      {
        compressorOff(); // Stop compressor
        modeTime=loopTime;
        if (T61<7) mode=40; else  mode=50;
      }
      if (loopTime-modeTime>checkDefrostTime) mode=11;
      break;

    case 11 : //Heating and check for defrost
      if (T63>highTemperatureLimit) // Stop heating 
      {
        compressorOff(); // Stop compressor
        modeTime=loopTime;
        if (T61<7) mode=40; else  mode=50;
      }
      
      if (T61-T62>defrostStartTemperature) // Stop for defrosting
      {
        compressorOff(); // Stop compressor
        modeTime=loopTime;
        if(T61>2) mode=20; //Hot defrost
        else mode=30; //Cold defrost
      }
      break;

    case 20: //Hot defrosting
      if (T62>1 && loopTime-modeTime>hotDefrostTime) //Hot defrost time
      {
        modeTime=loopTime;
        mode=99;
      }
      break;

    case 30 : //Afterheating time for fan and 4-way valve before defrosting
      if (loopTime-modeTime>modeDelay)
      {
        fanOff(); // Stop fan & 4-way valve
        modeTime=loopTime;
        mode=31;
      }
      break;
    
    case 31 : //Compressor start delay
      if (loopTime-modeTime>120000)
      {
        compressorOn(); // Start compressor
        modeTime=loopTime;
        mode=32;
      }
      break;
    
    case 32 : //Defrosting stage 1
      if (loopTime-modeTime>minDefrostTime) //Min defrosting time elapsed
      {
        mode=33;
      }
      break;
      
    case 33 : //Defrosting stage 2
      if (loopTime-modeTime>maxDefrostTime || T62>defrostEndtTemperature) //Stop defrosting
      {
        compressorOff(); // Stop compressor
        modeTime=loopTime;
        mode=34;
      }
      break;
      
    case 34: //Defrosting stage 3
      if (loopTime-modeTime>modeDelay)
      {
        fanOn();
        modeTime=loopTime;
        mode=99;
      }
      break;

    case 40: //Overheat or setpoint reached
      if (loopTime-modeTime>afterOverheatTimeL)
      {
        modeTime=loopTime;
        mode=99;
      }
      break;

    case 50: //Overheat or setpoint reached
      if (loopTime-modeTime>modeDelay)
      {
        fanOff(); // Stop fan & 4-way valve
        modeTime=loopTime;
        mode=51;
      }
      break;

    case 51: //Pause after overheat
      if (loopTime-modeTime>afterOverheatTimeH)
      {
        modeTime=loopTime;
        mode=99;
      }
      break;

    case 70 : //Stop delay
      if (loopTime-modeTime>modeDelay)
      {
        compressorOff();
        modeTime=loopTime;
        mode=71;
      }
      break;

    case 71 : //Circulation pump time after switch Off
      if (loopTime-modeTime>modeDelay)
      {
        pumpOff(); // Stop pump
        fanOff(); // Stop fan & 4-way valve
        modeTime=loopTime;
        mode=0;
      }
      break;

    case 80 : //Circulation fault
      compressorOff();
      modeTime=loopTime;
      mode=81;
      break;

    case 81 : //Time after compressor stop
      if (loopTime-modeTime>modeDelay)
      {
        pumpOff(); // Stop pump
        fanOff(); // Stop fan & 4-way valve
        modeTime=loopTime;
        mode=0;
      }
      break;

    case 99 : //Fan after time
      if (loopTime-modeTime>modeDelay)
      {
        fanOff(); // Stop fan & 4-way valve
        modeTime=loopTime;
        mode=1;
      }
      break;
    
    default: mode=0; 
  }  
}

void compressorOn()
{
  digitalWrite(pinCompressor, 0); // Start compressor
}

void compressorOff()
{
  digitalWrite(pinCompressor, 1); // Stop compressor
}

void fanOn()
{
  digitalWrite(pinFan, 0); // Start fan & 4-way valve
}

void fanOff()
{
  digitalWrite(pinFan, 1); // Stop fan & 4-way valve
}

void pumpOn()
{
  digitalWrite(pinPump, 0); // Start water circulation pump
}

void pumpOff()
{
  digitalWrite(pinPump, 1); // Stop water circulation pump
}

void heaterOn()
{
  digitalWrite(pinHeater, 0); // Start defrost heater
}

void heaterOff()
{
  digitalWrite(pinHeater, 1); // Stop defrost heater
}

void flowCalculation()
{
  if (lastFlowPulseTime==FlowPulseTime)
  {
    if (loopTime-lastFlowPulseTime>9999) F=0;
  }
  else
  {
    PulsePeriod=lastFlowPulseTime-FlowPulseTime; 
    F=3600000/PulsePeriod;    
    if (F>2000 || F<0) F=0;
    temp_f=Q62f;
    Q62f=(T62-T63)*0.00115+temp_f;
    FlowPulseTime=lastFlowPulseTime;
  }  
}

void FlowPulseSet()
{
  lastFlowPulseTime=millis();
}

void sensorsRead() 
{
  if (loopTime-SensorsReadTime>sensorsTime)
  {
    SensorsReadTime=loopTime;
    //Ambient air temperature
    datastreamTemp[0]=readSensor(pinT61);
    if (datastreamTemp[0]>-90 && datastreamTemp[0]<85) datastreamNew[0]=datastreamTemp[0];
    startConversion(pinT61);
    T61=datastreamNew[0];
    
    //Evaporator temperature
    datastreamTemp[1]=readSensor(pinT62);
    if (datastreamTemp[1]>-90 && datastreamTemp[1]<85) datastreamNew[1]=datastreamTemp[1];
    startConversion(pinT62);
    T62=datastreamNew[1];
    
    //Condenser temperature
    datastreamTemp[2]=readSensor(pinT63);
    if (datastreamTemp[2]>-90 && datastreamTemp[2]<85) datastreamNew[2]=datastreamTemp[2];
    startConversion(pinT63);
    T63=datastreamNew[2];
    //Manual On switch
    if (digitalRead(pinSwitch)) switchOn=0;
    else switchOn=1;
    
    datastreamNew[3]=mode;
    datastreamNew[4]=digitalRead(pinSwitch);
    datastreamNew[5]=digitalRead(pinCompressor);
    datastreamNew[6]=digitalRead(pinFan);
    datastreamNew[7]=digitalRead(pinPump);
    datastreamNew[8]=digitalRead(pinHeater);

  Serial.print("switchOn=");
  Serial.print(switchOn);  
  Serial.print("T61: ");
  Serial.print(T61);
  Serial.print(" degC; T62: ");
  Serial.print(T62);
  Serial.print(" degC; T63: ");
  Serial.println(T63);
  }
}

void sendData() 
{
  if (loopTime-sendTime>feedTime)
  {
    sendTime=loopTime ;
    for ( i = 0; i < datastreamsNumber; i++) datastreams[i].setFloat(datastreamNew[i]);
    //  Serial.println("Uploading it to Xively");
    ret = xivelyclient.put(feed, xivelyKey);
    //  Serial.print("xivelyclient.put returned ");
    //  Serial.println(ret);
    if (ret==200) for ( i = 0; i <  datastreamsNumber; i++) datastreamUpdated[i]=datastreamNew[i];
    digitalClockDisplay();
  }  
}

void startConversion(byte pin) // Start temperature conversion
{
//  Serial.print("Start temperature conversion 1-wire sensor on pin");
//  Serial.println(int (pin));
  OneWire ds(pin);
  ds.reset();
  ds.write(0xCC);         // Skip ROM command.
  ds.write(0x44,1);         // start conversion, with parasite power on at the end
}

float readSensor(byte pin) // Read 13 bit resolution temperature sensor DS18B20
{
//  Serial.print("Read temperature 1-wire sensor on pin");
//  Serial.println(int (pin));
  OneWire ds(pin);
  int16_t raw;
  float raw_f;
  ds.reset();
  ds.write(0xCC);         // Skip ROM command.
  ds.write(0xBE);         // Read Scratchpad

  for ( i = 0; i < 9; i++) 
  {           // we need 9 bytes
    data[i] = ds.read();
//    Serial.print(data[i], HEX);
//    Serial.print(" ");
  }
//  Serial.print(" CRC=");
//  Serial.print( OneWire::crc8( data, 8), HEX);
//  Serial.println();

//  Serial.print(" CRC from device=");
//  Serial.print( data[8], HEX);
//  Serial.println();

  if (OneWire::crc8( data, 8)==data[8])
  {
    raw = (((int16_t) data[1]) << 8) | data[0];
    raw_f=(float)raw/16;
  }
  if (OneWire::crc8( data, 8)!=data[8]) // CRC error
  {
    raw_f=-98;
  }
  if (data[8]==0) // Short circuit between data wire and ground
  {
    raw_f=-99;
  }
  if (data[8]==255) // Wire break
  {
    raw_f=-97; 
  }
//  Serial.println(raw_f);  
  return raw_f;
}

void webServer()
{
  // listen for incoming clients
  EthernetClient webclient = webserver.available();
//  Client webclient = webserver.available();

  if (webclient) 
  {
    // an http request ends with a blank line
    boolean currentLineIsBlank = true;
    while (webclient.connected()) 
    {
      if (webclient.available()) 
      {
        char c = webclient.read();
        // if you've gotten to the end of the line (received a newline
        // character) and the line is blank, the http request has ended,
        // so you can send a reply
        if (c == '\n' && currentLineIsBlank) 
        {
          // send a standard http response header
          webclient.println("HTTP/1.1 200 OK");
          webclient.println("Content-Type: text/html");
          webclient.println();

          webclient.print("loop time: ");
          webclient.print(loopTime/1000);
          webclient.print(" <br>");

          webclient.print("sendTime: ");
          webclient.print(sendTime/1000);
          webclient.print(" <br>");

          webclient.print("eepromTime: ");
          webclient.print(eepromTime/1000);
          webclient.print(" <br>");

          webclient.print("imp1: ");
          webclient.print(imp1);
          webclient.print(" <br>");

          webclient.print("imp2: ");
          webclient.print(imp2);
          webclient.print(" <br>");

          webclient.print("Ambient air temperature: ");
          webclient.print(datastreams[0]);
          webclient.print("temp: ");
          webclient.print(datastreamTemp[0]);
          webclient.print(" <sup>o</sup>C<br>");
    
          webclient.print("Evaporator temperature: ");
          webclient.print(datastreams[1]);
          webclient.print("temp: ");
          webclient.print(datastreamTemp[1]);
          webclient.print(" <sup>o</sup>C<br>");
    
          webclient.print("Condenser temperature: ");
          webclient.print(datastreams[2]);
          webclient.print("temp: ");
          webclient.print(datastreamTemp[2]);
          webclient.print(" <sup>o</sup>C<br>");
          
          webclient.print("Mode: ");
          webclient.print(mode);
          webclient.print("<br>");
    
          webclient.print("Switch: ");
          webclient.print(switchOn);
          webclient.print("<br>");
    
          webclient.print(codeVersion);
          webclient.print("<br>xivelyclient.put returned ");
          webclient.print(ret);
        
    // digital clock display of the time
          webclient.print("<br>");
          webclient.print(hour());
          webclient.print(":");
          if(minute() < 10) webclient.print("0");
          webclient.print(minute());
          webclient.print(":");
          if(second() < 10) webclient.print("0");
          webclient.print(second());
          webclient.print(" ");
          webclient.print(day());
          webclient.print(".");
          webclient.print(month());
          webclient.print(".");
          webclient.print(year());
      break;
      }
      if (c == '\n') 
      {
        // you're starting a new line
        currentLineIsBlank = true;
      } 
      else if (c != '\r')   
      {
          // you've gotten a character on the current line
          currentLineIsBlank = false;
      }
      }
    }
    // give the web browser time to receive the data
    delay(1);
    // close the connection:
    webclient.stop();
  }
}


void digitalClockDisplay(){
  // digital clock display of the time
  Serial.print(hour());
  printDigits(minute());
  printDigits(second());
  Serial.print(" ");
  Serial.print(day());
  Serial.print(".");
  Serial.print(month());
  Serial.print(".");
  Serial.print(year()); 
  Serial.println(); 
}

void printDigits(int digits){
  // utility for digital clock display: prints preceding colon and leading 0
  Serial.print(":");
  if(digits < 10)
    Serial.print('0');
  Serial.print(digits);
}

/*-------- NTP code ----------*/

const int NTP_PACKET_SIZE = 48; // NTP time is in the first 48 bytes of message
byte packetBuffer[NTP_PACKET_SIZE]; //buffer to hold incoming & outgoing packets

time_t getNtpTime()
{
  while (Udp.parsePacket() > 0) ; // discard any previously received packets
  Serial.println("Transmit NTP Request");
  sendNTPpacket(timeServer);
  uint32_t beginWait = millis();
  while (millis() - beginWait < 1500) {
    int size = Udp.parsePacket();
    if (size >= NTP_PACKET_SIZE) {
      Serial.println("Receive NTP Response");
      Udp.read(packetBuffer, NTP_PACKET_SIZE);  // read packet into the buffer
      unsigned long secsSince1900;
      // convert four bytes starting at location 40 to a long integer
      secsSince1900 =  (unsigned long)packetBuffer[40] << 24;
      secsSince1900 |= (unsigned long)packetBuffer[41] << 16;
      secsSince1900 |= (unsigned long)packetBuffer[42] << 8;
      secsSince1900 |= (unsigned long)packetBuffer[43];
      return secsSince1900 - 2208988800UL + timeZone * SECS_PER_HOUR;
    }
  }
  Serial.println("No NTP Response :-(");
  return 0; // return 0 if unable to get the time
}

// send an NTP request to the time server at the given address
void sendNTPpacket(IPAddress &address)
{
  // 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();
}