Arduino: Ethernet NTP Sync, dan timer untuk Play Audio

Code

// time ntp sync

#include <Time.h>
#include <SPI.h>
#include <Ethernet.h>
#include <EthernetUdp.h>
#include "TMRpcm.h"
#include <SD.h>

// Ethernet library configuration
byte mac[] = { 0x24, 0x7B, 0xA2, 0x4A, 0x52, 0x10 };
IPAddress timeServer(128, 138, 140, 44 );

unsigned int localPort = 8888;
const int NTP_PACKET_SIZE= 48;     
byte packetBuffer[NTP_PACKET_SIZE]; 
EthernetUDP Udp;                   

const int CS_PIN = 4;
TMRpcm audio;

void setup() {
  pinMode(13, OUTPUT);
  audio.speakerPin = 9;
  audio.setVolume(3);
  Serial.begin(9600);
  pinMode(CS_PIN, OUTPUT);
  SD.begin(CS_PIN);
  Ethernet.begin(mac);
  
  setSyncInterval(10); // Set seconds between re-sync (5s for test only)
  getNtpTime;
  Udp.begin(localPort);
}

void loop() {
  setSyncProvider(getNtpTime);
  
  if(audio.isPlaying()==0) digitalWrite(13, LOW);
    else digitalWrite(13, HIGH);
    
  if( minute()==0||minute()==1 )
    if(audio.isPlaying()==0) {
      digitalWrite(13, HIGH);
      audio.play("MORAT.WAV");
      delay(2L*60L*1000);
      }
  if( minute()==30||minute()==31 )
    if(audio.isPlaying()==0) {
      digitalWrite(13, HIGH);
      audio.play("MORAT.WAV");
      delay(2L*60L*1000);
      }
  getNtpTime;
  delay(10*1000);
} 

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

unsigned long getNtpTime()
{
  sendNTPpacket(timeServer); // send an NTP packet to a time server
    delay(500);
   
    if ( Udp.parsePacket() ) {
     Udp.read(packetBuffer,NTP_PACKET_SIZE);
     unsigned long hi = word(packetBuffer[40], packetBuffer[41]);
     unsigned long low = word(packetBuffer[42], packetBuffer[43]);
     unsigned long secsSince1900 = hi << 16 | low; 
     const unsigned long seventyYears = 2208988800UL;     
     unsigned long epoch = secsSince1900 - seventyYears;
     return epoch;
  }
  return 0; // return 0 if unable to get the time
}

unsigned long sendNTPpacket(IPAddress& address)
{
  memset(packetBuffer, 0, NTP_PACKET_SIZE);  // set all bytes in the buffer to 0

  // Initialize values needed to form NTP request
  packetBuffer[0] = B11100011;   // LI, Version, Mode
  packetBuffer[1] = 0;     // Stratum
  packetBuffer[2] = 6;     // Max Interval between messages in seconds
  packetBuffer[3] = 0xEC;  // Clock Precision
  // bytes 4 - 11 are for Root Delay and Dispersion and were set to 0 by memset
  packetBuffer[12]  = 49;  // four-byte reference ID identifying
  packetBuffer[13]  = 0x4E;
  packetBuffer[14]  = 49;
  packetBuffer[15]  = 52; 

  // send the packet requesting a timestamp:
  Udp.beginPacket(address, 123); //NTP requests are to port 123
  Udp.write(packetBuffer,NTP_PACKET_SIZE);
  Udp.endPacket();
}