DS3231.cpp

// DS3231 Class is by Seeed Technology Inc(http://www.seeedstudio.com) and used
// in Seeeduino Stalker v2.1 for battery management(MCU power saving mode)
// & to generate timestamp for data logging. DateTime Class is a modified
// version supporting day-of-week.

// Original DateTime Class and its utility code is by Jean-Claude Wippler at JeeLabs
// http://jeelabs.net/projects/cafe/wiki/RTClib 
// Released under MIT License http://opensource.org/licenses/mit-license.php



#include <DS3231.h>

// These included for the DateTime class inclusion; will try to find a way to
// not need them in the future...
#include <avr/pgmspace.h>
// Changed the following to work on 1.0
//#include "WProgram.h"
#include <Arduino.h>


#define SECONDS_PER_DAY 86400L

////////////////////////////////////////////////////////////////////////////////
// utility code, some of this could be exposed in the DateTime API if needed

const uint8_t daysInMonth [] PROGMEM = { 31,28,31,30,31,30,31,31,30,31,30,31 };

// number of days since 2000/01/01, valid for 2001..2099
static uint16_t date2days(uint16_t y, uint8_t m, uint8_t d) {
		if (y >= 2000)
				y -= 2000;
		uint16_t days = d;
		for (uint8_t i = 1; i < m; ++i)
				days += pgm_read_byte(daysInMonth + i - 1);
		if (m > 2 && y % 4 == 0)
				++days;
		return days + 365 * y + (y + 3) / 4 - 1;
}

static long time2long(uint16_t days, uint8_t h, uint8_t m, uint8_t s) {
		return ((days * 24L + h) * 60 + m) * 60 + s;
}

static uint8_t conv2d(const char* p) {
		uint8_t v = 0;
		if ('0' <= *p && *p <= '9')
				v = *p - '0';
		return 10 * v + *++p - '0';
}

////////////////////////////////////////////////////////////////////////////////
// DateTime implementation - ignores time zones and DST changes
// NOTE: also ignores leap seconds, see http://en.wikipedia.org/wiki/Leap_second

DateTime::DateTime (long t) {
		t -= SECONDS_FROM_1970_TO_2000;    // bring to 2000 timestamp from 1970

		ss = t % 60;
		t /= 60;
		mm = t % 60;
		t /= 60;
		hh = t % 24;
		uint16_t days = t / 24;
		uint8_t leap;
		for (yOff = 0; ; ++yOff) {
				leap = yOff % 4 == 0;
				if (days < 365 + leap)
						break;
				days -= 365 + leap;
		}
		for (m = 1; ; ++m) {
				uint8_t daysPerMonth = pgm_read_byte(daysInMonth + m - 1);
				if (leap && m == 2)
						++daysPerMonth;
				if (days < daysPerMonth)
						break;
				days -= daysPerMonth;
		}
		d = days + 1;
}

DateTime::DateTime (uint16_t year, uint8_t month, uint8_t date, uint8_t hour, uint8_t min, uint8_t sec, uint8_t wd) {
		if (year >= 2000)
				year -= 2000;
		yOff = year;
		m = month;
		d = date;
		hh = hour;
		mm = min;
		ss = sec;
		wday = wd;
}

// A convenient constructor for using "the compiler's time":
//   DateTime now (__DATE__, __TIME__);
// NOTE: using PSTR would further reduce the RAM footprint
DateTime::DateTime (const char* date, const char* time) {
		// sample input: date = "Dec 26 2009", time = "12:34:56"
		yOff = conv2d(date + 9);
		// Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec 
		switch (date[0]) {
				case 'J': m = date[1] == 'a' ? 1 : m = date[2] == 'n' ? 6 : 7; break;
				case 'F': m = 2; break;
				case 'A': m = date[2] == 'r' ? 4 : 8; break;
				case 'M': m = date[2] == 'r' ? 3 : 5; break;
				case 'S': m = 9; break;
				case 'O': m = 10; break;
				case 'N': m = 11; break;
				case 'D': m = 12; break;
		}
		d = conv2d(date + 4);
		hh = conv2d(time);
		mm = conv2d(time + 3);
		ss = conv2d(time + 6);
}

uint32_t DateTime::unixtime(void) const {
	uint32_t t;
	uint16_t days = date2days(yOff, m, d);
	t = time2long(days, hh, mm, ss);
	t += SECONDS_FROM_1970_TO_2000;  // seconds from 1970 to 2000
	return t;
}

long DateTime::secondstime(void) const {
	long t;
	uint16_t days = date2days(yOff, m, d);
	t = time2long(days, hh, mm, ss);
	return t;
}

static uint8_t bcd2bin (uint8_t val) { return val - 6 * (val >> 4); }
static uint8_t bin2bcd (uint8_t val) { return val + 6 * (val / 10); }



////////////////////////////////////////////////////////////////////////////////
// RTC DS3231 implementation

uint8_t DS3231::readRegister(uint8_t regaddress)
{
		Wire.beginTransmission(DS3231_ADDRESS);
		Wire.write(regaddress);
		Wire.endTransmission();

		Wire.requestFrom(DS3231_ADDRESS, 1);
		return Wire.read();
}

void DS3231::writeRegister(uint8_t regaddress,uint8_t value)
{
		Wire.beginTransmission(DS3231_ADDRESS);
		Wire.write(regaddress);
		Wire.write(value);
		Wire.endTransmission();
}

uint8_t DS3231::begin(void) {

	unsigned char ctReg=0;
	ctReg |= 0b00011100; 
	writeRegister(DS3231_CONTROL_REG, ctReg);     //CONTROL Register Address
	delay(10);

	// set the clock to 24hr format  
	uint8_t hrReg = readRegister(DS3231_HOUR_REG);
	hrReg &= 0b10111111;
	writeRegister(DS3231_HOUR_REG, hrReg);       

	delay(10);

	return 1; 
}

//Adjust the time-date specified in DateTime format
//writing any non-existent time-data may interfere with normal operation of the RTC
void DS3231::adjust(const DateTime& dt) {

	Wire.beginTransmission(DS3231_ADDRESS);
	Wire.write((byte)DS3231_SEC_REG);  //beginning from SEC Register address

	Wire.write(bin2bcd(dt.second())); 
	Wire.write(bin2bcd(dt.minute()));
	Wire.write(bin2bcd((dt.hour()) & 0b10111111)); //Make sure clock is still 24 Hour
	Wire.write(dt.dayOfWeek());
	Wire.write(bin2bcd(dt.date()));
	Wire.write(bin2bcd(dt.month()));
	Wire.write(bin2bcd(dt.year() - 2000));  
	Wire.endTransmission();

}

//Read the current time-date and return it in DateTime format
DateTime DS3231::now() {
	Wire.beginTransmission(DS3231_ADDRESS);
	Wire.write((byte)0x00);	
	Wire.endTransmission();
	
	Wire.requestFrom(DS3231_ADDRESS, 8);
	uint8_t ss = bcd2bin(Wire.read());
	uint8_t mm = bcd2bin(Wire.read());
	 
	uint8_t hrreg = Wire.read();
	uint8_t hh = bcd2bin((hrreg & ~0b11000000)); //Ignore 24 Hour bit

	uint8_t wd =  Wire.read();
	uint8_t d = bcd2bin(Wire.read());
	uint8_t m = bcd2bin(Wire.read());
	uint16_t y = bcd2bin(Wire.read()) + 2000;
	
	return DateTime (y, m, d, hh, mm, ss, wd);
}

//Enable periodic interrupt at /INT pin. Supports only the level interrupt
//for consistency with other /INT interrupts. All interrupts works like single-shot counter
//Use refreshINTA() to re-enable interrupt.
void DS3231::enableAlarm(uint8_t periodicity)
{
		unsigned char ctReg=0;
		ctReg |= 0b00011101; 
		writeRegister(DS3231_CONTROL_REG, ctReg);     //CONTROL Register Address
		
	 switch(periodicity) 
	 {
			 case EverySecond:
			 writeRegister(DS3231_AL1SEC_REG,  0b10000000 ); //set AM1
			 writeRegister(DS3231_AL1MIN_REG,  0b10000000 ); //set AM2
			 writeRegister(DS3231_AL1HOUR_REG, 0b10000000 ); //set AM3
			 writeRegister(DS3231_AL1WDAY_REG, 0b10000000 ); //set AM4

			 break;

			 case EveryMinute:
			 writeRegister(DS3231_AL1SEC_REG,  0b00000000 ); //Clr AM1
			 writeRegister(DS3231_AL1MIN_REG,  0b10000000 ); //set AM2
			 writeRegister(DS3231_AL1HOUR_REG, 0b10000000 ); //set AM3
			 writeRegister(DS3231_AL1WDAY_REG, 0b10000000 ); //set AM4

			 break;

			 case EveryHour:
			 writeRegister(DS3231_AL1SEC_REG,  0b00000000 ); //Clr AM1
			 writeRegister(DS3231_AL1MIN_REG,  0b00000000 ); //Clr AM2
			 writeRegister(DS3231_AL1HOUR_REG, 0b10000000 ); //Set AM3
			 writeRegister(DS3231_AL1WDAY_REG, 0b10000000 ); //set AM4

			 break;
	 }
}

//Enable HH/MM/SS interrupt on /INTA pin. All interrupts works like single-shot counter
void DS3231::enableAlarm(uint8_t hh24, uint8_t mm, uint8_t ss)
{
		unsigned char ctReg=0;
		ctReg |= 0b00011101; 
		writeRegister(DS3231_CONTROL_REG, ctReg);     //CONTROL Register Address

		writeRegister(DS3231_AL1SEC_REG,  0b00000000 | bin2bcd(ss) ); //Clr AM1
		writeRegister(DS3231_AL1MIN_REG,  0b00000000 | bin2bcd(mm)); //Clr AM2
		writeRegister(DS3231_AL1HOUR_REG, (0b00000000 | (bin2bcd(hh24) & 0b10111111))); //Clr AM3
		writeRegister(DS3231_AL1WDAY_REG, 0b10000000 ); //set AM4
}

void DS3231::enableAlarm(const DateTime& dt) 
{
	unsigned char ctReg=0;
	ctReg |= 0b00011101; 
	writeRegister(DS3231_CONTROL_REG, ctReg);     //CONTROL Register Address

	writeRegister(DS3231_AL1SEC_REG,  0b00000000 | bin2bcd(dt.second()) ); //Clr AM1
	writeRegister(DS3231_AL1MIN_REG,  0b00000000 | bin2bcd(dt.minute())); //Clr AM2
	writeRegister(DS3231_AL1HOUR_REG, (0b00000000 | (bin2bcd(dt.hour()) & 0b10111111))); //Clr AM3
	writeRegister(DS3231_AL1WDAY_REG, 0b10000000 ); //set AM4

}

//Disable Interrupts. This is equivalent to begin() method.
void DS3231::disableAlarm()
{
		begin(); //Restore to initial value.
}

//Clears the interrrupt flag in status register. 
//This is equivalent to preparing the DS3231 /INT pin to high for MCU to get ready for recognizing the next INT0 interrupt
void DS3231::clearAlarm()
{
		// Clear interrupt flag 
		uint8_t statusReg = readRegister(DS3231_STATUS_REG);
		statusReg &= 0b11111110;
		writeRegister(DS3231_STATUS_REG, statusReg);

}

//force temperature sampling and converting to registers. If this function is not used the temperature is sampled once 64 Sec.
void DS3231::convertTemperature()
{
		// Set CONV 
		uint8_t ctReg = readRegister(DS3231_CONTROL_REG);
		ctReg |= 0b00100000; 
		writeRegister(DS3231_CONTROL_REG,ctReg); 
 

		//wait until CONV is cleared. Indicates new temperature value is available in register.
		do
		{
			 //do nothing
		} while ((readRegister(DS3231_CONTROL_REG) & 0b00100000) == 0b00100000 ); 
 
}

//Read the temperature value from the register and convert it into float (deg C)
float DS3231::getTemperature()
{
		int   temperatureCelsius;
		float fTemperatureCelsius;
		uint8_t tUBYTE  = readRegister(DS3231_TMP_UP_REG);  //Two's complement form
		uint8_t tLRBYTE = readRegister(DS3231_TMP_LOW_REG); //Fractional part
	
		if(tUBYTE & 0b10000000) //check if -ve number
		{
			 tUBYTE  ^= 0b11111111;  
			 tUBYTE  += 0x1;
			 fTemperatureCelsius = tUBYTE + ((tLRBYTE >> 6) * 0.25);
			 fTemperatureCelsius = fTemperatureCelsius * -1;
		}
		else
		{
				fTemperatureCelsius = tUBYTE + ((tLRBYTE >> 6) * 0.25); 
		}
 
		return (fTemperatureCelsius);
			
}