Arduino: RTC DS3231 PC Sync

Sumber: http://playground.arduino.cc/Code/time

Siapkan Library

Download dari

• http://playground.arduino.cc/uploads/Code/Time.zip

Extrak

cd /usr/share/arduino/libraries/

atau

cd ~/Arduino/libraries

wget http://playground.arduino.cc/uploads/Code/Time.zip
unzip Time.zip
cd Time
gedit DateStrings.cpp 

Tambahkan di

char   > char  const
PGM_P  > PGM_P const

Code

#include "Wire.h"
#include <Time.h>  

#define TIME_MSG_LEN  11   // time sync to PC is HEADER followed by Unix time_t as ten ASCII digits
#define TIME_HEADER  'T'   // Header tag for serial time sync message
#define TIME_REQUEST  7    // ASCII bell character requests a time sync message

#define DS3231_I2C_ADDRESS 0x68
// Convert normal decimal numbers to binary coded decimal
byte decToBcd(byte val)
{
  return ( (val / 10 * 16) + (val % 10) );
}
// Convert binary coded decimal to normal decimal numbers
byte bcdToDec(byte val)
{
  return ( (val / 16 * 10) + (val % 16) );
}
void setup()
{
  Wire.begin();
  Serial.begin(9600);
  
  // set the initial time here:
  // DS3231 seconds, minutes, hours, day, date, month, year
  // setDS3231time(30,33,9, 2 ,28,11,16);
}
void setDS3231time(byte second, byte minute, byte hour, byte dayOfWeek, byte
                   dayOfMonth, byte month, byte year)
{
  // sets time and date data to DS3231
  Wire.beginTransmission(DS3231_I2C_ADDRESS);
  Wire.write(0); // set next input to start at the seconds register
  Wire.write(decToBcd(second)); // set seconds
  Wire.write(decToBcd(minute)); // set minutes
  Wire.write(decToBcd(hour)); // set hours
  Wire.write(decToBcd(dayOfWeek)); // set day of week (1=Sunday, 7=Saturday)
  Wire.write(decToBcd(dayOfMonth)); // set date (1 to 31)
  Wire.write(decToBcd(month)); // set month
  Wire.write(decToBcd(year)); // set year (0 to 99)
  Wire.endTransmission();
}
void readDS3231time(byte *second,
                    byte *minute,
                    byte *hour,
                    byte *dayOfWeek,
                    byte *dayOfMonth,
                    byte *month,
                    byte *year)
{
  Wire.beginTransmission(DS3231_I2C_ADDRESS);
  Wire.write(0); // set DS3231 register pointer to 00h
  Wire.endTransmission();
  Wire.requestFrom(DS3231_I2C_ADDRESS, 7);
  // request seven bytes of data from DS3231 starting from register 00h
  *second = bcdToDec(Wire.read() & 0x7f);
  *minute = bcdToDec(Wire.read());
  *hour = bcdToDec(Wire.read() & 0x3f);
  *dayOfWeek = bcdToDec(Wire.read());
  *dayOfMonth = bcdToDec(Wire.read());
  *month = bcdToDec(Wire.read());
  *year = bcdToDec(Wire.read());
}
void displayTime()
{
  byte second, minute, hour, dayOfWeek, dayOfMonth, month, year;
  // retrieve data from DS3231
  readDS3231time(&second, &minute, &hour, &dayOfWeek, &dayOfMonth, &month,
                 &year);
  // send it to the serial monitor
  Serial.print(hour, DEC);
  // convert the byte variable to a decimal number when displayed
  Serial.print(":");
  if (minute < 10)
  {
    Serial.print("0");
  }
  Serial.print(minute, DEC);
  Serial.print(":");
  if (second < 10)
  {
    Serial.print("0");
  }
  Serial.print(second, DEC);
  Serial.print(" ");
  Serial.print(dayOfMonth, DEC);
  Serial.print("/");
  Serial.print(month, DEC);
  Serial.print("/");
  Serial.print(year, DEC);
  Serial.print(" Day of week: ");
  switch (dayOfWeek) {
    case 1:
      Serial.println("Sunday");
      break;
    case 2:
      Serial.println("Monday");
      break;
    case 3:
      Serial.println("Tuesday");
      break;
    case 4:
      Serial.println("Wednesday");
      break;
    case 5:
      Serial.println("Thursday");
      break;
    case 6:
      Serial.println("Friday");
      break;
    case 7:
      Serial.println("Saturday");
      break;
  }
}

void loop(){    
  if(Serial.available() )
  {
    processSyncMessage();
  }
  if(timeStatus() == timeNotSet)
    Serial.println("waiting for sync message");
  else    
     // digitalClockDisplay();  
      displayTime();
  delay(1000);
}

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 function for digital clock display: prints preceding colon and leading 0
  Serial.print(":");
  if(digits < 10)
    Serial.print('0');
  Serial.print(digits);
}

void processSyncMessage() {
  // if time sync available from serial port, update time and return true
  while(Serial.available() >=  TIME_MSG_LEN ){  // time message consists of header & 10 ASCII digits
    char c = Serial.read() ;
    Serial.print(c);  
    if( c == TIME_HEADER ) {      
      time_t pctime = 0;
      for(int i=0; i < TIME_MSG_LEN -1; i++){  
        c = Serial.read();          
        if( c >= '0' && c <= '9'){  
          pctime = (10 * pctime) + (c - '0') ; // convert digits to a number    
        }
      }  
      setTime(pctime);   // Sync Arduino clock to the time received on the serial port
      // set the initial time here:
      // DS3231 seconds, minutes, hours, day, date, month, year
      setDS3231time(second(),minute(),hour()+7, 5 , 7, 6, 18);
    }  
  }
}

PC Sync

Lakukan

date +T%s\n > /dev/ttyACM0

Untuk mensinkronisasi waktu

Referensi

• http://playground.arduino.cc/Code/time