Hello everybody,
some of you might want to work with the DS1307 real time clock (RTC) on an Arduino board.
The libraries that I could find so far seemed to me mostly a bit difficult to work with.
So I adapted a different one for Arduino 1.0 and above that I found much more comfortable to use. It was tested to work fine with Arduino 1.5.
I am not the original author of this library. Though I can't trace back it's origin anymore.
Here the header:
/*
DS1307.h - library for DS1307 RTC
for Arduino 1.0 and above
June 28th, 2013
*/
// ensure this library description is only included once
#ifndef DS1307_h
#define DS1307_h
// include types & constants of Wiring core API
//#include <WConstants.h>
#include <Arduino.h>
// include types & constants of Wire ic2 lib
#include <Wire.h>
#define DS1307_SEC 0
#define DS1307_MIN 1
#define DS1307_HR 2
#define DS1307_DOW 3
#define DS1307_DATE 4
#define DS1307_MTH 5
#define DS1307_YR 6
#define DS1307_BASE_YR 2010
#define DS1307_CTRL_ID B1101000 //DS1307
// Define register bit masks
#define DS1307_CLOCKHALT B10000000
#define DS1307_LO_BCD B00001111
#define DS1307_HI_BCD B11110000
#define DS1307_HI_SEC B01110000
#define DS1307_HI_MIN B01110000
#define DS1307_HI_HR B00110000
#define DS1307_LO_DOW B00000111
#define DS1307_HI_DATE B00110000
#define DS1307_HI_MTH B00110000
#define DS1307_HI_YR B11110000
// library interface description
class DS1307
{
// user-accessible "public" interface
public:
DS1307();
void init();
void get(int *rtc, boolean);
int get(int, boolean);
void set(int, int);
void start(void);
void stop(void);
// library-accessible "private" interface
private:
byte rtc_bcd[7]; // used prior to read/set ds1307 registers;
void read(void);
void save(void);
};
//extern DS1307 RTC;
#endif
the source:
/*
DS1307.cpp - library for DS1307 RTC
for Arduino 1.0 and above
June 28th, 2013
*/
#include <Arduino.h>
#include <Wire.h>
#include "DS1307.h"
DS1307::DS1307()
{
//Wire.begin();
}
//DS1307 RTC=DS1307();
void DS1307::init(){
Wire.begin();
}
// PRIVATE FUNCTIONS
// Aquire data from the RTC chip in BCD format
// refresh the buffer
void DS1307::read(void)
{
// use the Wire lib to connect to tho rtc
// reset the resgiter pointer to zero
Wire.beginTransmission(DS1307_CTRL_ID);
byte val = 0x00;
Wire.write(val);
Wire.endTransmission();
// request the 7 bytes of data (secs, min, hr, dow, date. mth, yr)
Wire.requestFrom(DS1307_CTRL_ID, 7);
for(int i=0; i<7; i++)
{
// store data in raw bcd format
rtc_bcd[i]=Wire.read();
}
}
// update the data on the IC from the bcd formatted data in the buffer
void DS1307::save(void)
{
Wire.beginTransmission(DS1307_CTRL_ID);
byte val = 0x00;
Wire.write(val); // reset register pointer
for(int i=0; i<7; i++)
{
Wire.write(rtc_bcd[i]);
}
Wire.endTransmission();
}
// PUBLIC FUNCTIONS
void DS1307::get(int *rtc, boolean refresh) // Aquire data from buffer and convert to int, refresh buffer if required
{
if(refresh) read();
for(int i=0;i<7;i++) // cycle through each component, create array of data
{
rtc[i]=get(i, 0);
}
}
int DS1307::get(int c, boolean refresh) // aquire individual RTC item from buffer, return as int, refresh buffer if required
{
if(refresh) read();
int v=-1;
switch(c)
{
case DS1307_SEC:
v=(10*((rtc_bcd[DS1307_SEC] & DS1307_HI_SEC)>>4))+(rtc_bcd[DS1307_SEC] & DS1307_LO_BCD);
break;
case DS1307_MIN:
v=(10*((rtc_bcd[DS1307_MIN] & DS1307_HI_MIN)>>4))+(rtc_bcd[DS1307_MIN] & DS1307_LO_BCD);
break;
case DS1307_HR:
v=(10*((rtc_bcd[DS1307_HR] & DS1307_HI_HR)>>4))+(rtc_bcd[DS1307_HR] & DS1307_LO_BCD);
break;
case DS1307_DOW:
v=rtc_bcd[DS1307_DOW] & DS1307_LO_DOW;
break;
case DS1307_DATE:
v=(10*((rtc_bcd[DS1307_DATE] & DS1307_HI_DATE)>>4))+(rtc_bcd[DS1307_DATE] & DS1307_LO_BCD);
break;
case DS1307_MTH:
v=(10*((rtc_bcd[DS1307_MTH] & DS1307_HI_MTH)>>4))+(rtc_bcd[DS1307_MTH] & DS1307_LO_BCD);
break;
case DS1307_YR:
v=(10*((rtc_bcd[DS1307_YR] & DS1307_HI_YR)>>4))+(rtc_bcd[DS1307_YR] & DS1307_LO_BCD)+DS1307_BASE_YR;
break;
} // end switch
return v;
}
void DS1307::set(int c, int v) // Update buffer, then update the chip
{
switch(c)
{
case DS1307_SEC:
if(v<60 && v>-1)
{
//preserve existing clock state (running/stopped)
int state=rtc_bcd[DS1307_SEC] & DS1307_CLOCKHALT;
rtc_bcd[DS1307_SEC]=state | ((v / 10)<<4) + (v % 10);
}
break;
case DS1307_MIN:
if(v<60 && v>-1)
{
rtc_bcd[DS1307_MIN]=((v / 10)<<4) + (v % 10);
}
break;
case DS1307_HR:
// TODO : AM/PM 12HR/24HR
if(v<24 && v>-1)
{
rtc_bcd[DS1307_HR]=((v / 10)<<4) + (v % 10);
}
break;
case DS1307_DOW:
if(v<8 && v>-1)
{
rtc_bcd[DS1307_DOW]=v;
}
break;
case DS1307_DATE:
if(v<31 && v>-1)
{
rtc_bcd[DS1307_DATE]=((v / 10)<<4) + (v % 10);
}
break;
case DS1307_MTH:
if(v<13 && v>-1)
{
rtc_bcd[DS1307_MTH]=((v / 10)<<4) + (v % 10);
}
break;
case DS1307_YR:
if(v<13 && v>-1)
{
rtc_bcd[DS1307_YR]=((v / 10)<<4) + (v % 10);
}
break;
} // end switch
save();
}
void DS1307::stop(void)
{
// set the ClockHalt bit high to stop the rtc
// this bit is part of the seconds byte
rtc_bcd[DS1307_SEC]=rtc_bcd[DS1307_SEC] | DS1307_CLOCKHALT;
save();
}
void DS1307::start(void)
{
// unset the ClockHalt bit to start the rtc
// TODO : preserve existing seconds
rtc_bcd[DS1307_SEC]=0;
save();
}
And an example .ino
#include <Wire.h>
#include "DS1307.h"
int rtc[7];
DS1307 RT = DS1307();
void setup()
{
Serial.begin(9600);
RT.init();
//*
RT.stop();
RT.set(DS1307_SEC,1);
RT.set(DS1307_MIN,0);
RT.set(DS1307_HR,18);
RT.set(DS1307_DOW,2);
RT.set(DS1307_DATE,11);
RT.set(DS1307_MTH,6);
RT.set(DS1307_YR,3);
RT.start();
//*/
}
void loop()
{
RT.get(rtc,true);
for(int i=0; i<7; i++)
{
Serial.print(rtc[i]);
Serial.print(" ");
}
Serial.println();
delay(1000);
}
Hope, it helps you as much as it helped me!
Cheers!