Dale un ojo a este archivo, te puede ser de mucha utilidad. La verdad lo encontré en un rincón de la web, y aún no lo he probado.
/*********************************************************************
DS1307.C
This file handles the Dallas DS1307 Real Time Clock on Horoscas
board.
It use the mbus driver to communicate with the DS1307.
**********************************************************************/
#include <stdlib.h>
#include <string.h>
#include <stdio.h>
#include <errno.h>
#include <getopt.h>
#include <fcntl.h>
#include "ds1302.h"
#define DS1307_ADDR 0xd0
static int mbus_fd;
/*******************************************************************
Setup_1302_Port
Initialize Port Pins to access DS1302 Clock.
Note that all three pins are defined initialliy as outputs.
When you want to read a port pin, you have to turn it
around.
MCF5206...
PP0 = CLOCK
PP1 = RST*
PP2 = DATA
********************************************************************/
void Setup_1302_Port(void)
{
if ((mbus_fd = open("/dev/mbus", O_RDWR)) < 0) {
perror("/dev/mbus"
;
exit(1);
}
}
/*******************************************************************
Lock_1302
This routine will LOCK the clock and stop its oscillator to
preserve Battery Life.
Uses TimeBuffer[] as temporary storage.
********************************************************************/
void Lock_1302 (void)
{
int result;
unsigned char buffer[4]; //temp storage
buffer[0] = DS1307_ADDR;
buffer[1] = 0;
if ((result = read(mbus_fd, buffer, 3)) != 3) {
fprintf(stderr, "DS1307 returned %d
", result);
exit(1);
}
buffer[2] |= 0x80;
if ((result = write(mbus_fd, buffer, 3)) != 3) {
fprintf(stderr, "DS1307 returned %d
", result);
exit(1);
}
} /* end proc Lock_1203() */
/*******************************************************************
Set_Time
This routine SETs the clock and start its oscillator, write-
protecting the clock registers.
Obtains time from TimeBuffer[].
********************************************************************/
void Set_Time(unsigned char * TimeBuffer)
{
int result;
unsigned char buffer[10];
TimeBuffer[7] = "x80"; //write protect the chip after write
buffer[0] = DS1307_ADDR;
buffer[1] = 0;
memcpy(&buffer[2], TimeBuffer,
;
if ((result = write(mbus_fd, buffer, 10)) != 10) {
fprintf(stderr, "DS1307 returned %d
", result);
exit(1);
}
} /* end proc Set_Time() */
/*******************************************************************
Get_Time
This routine GETs the time from the Dallas 1302 clock.
The time is returned in TimeBuffer.
This function returns 0 when the clock is operating properly.
If the clock was locked (stopped) the default time is returned
as 1/1/99, 12:00Noon and the function returns non-zero.
********************************************************************/
unsigned int Get_Time(unsigned char * TimeBuffer)
{
unsigned int clock_locked;
int result;
unsigned char buffer[10];
buffer[0] = DS1307_ADDR;
buffer[1] = 0;
if ((result = read(mbus_fd, buffer, 10)) != 10) {
fprintf(stderr, "DS1307 returned %d
", result);
exit(1);
}
memcpy(TimeBuffer, &buffer[2],
;
clock_locked = ((TimeBuffer[0] & 0x80) != 0);
return(clock_locked);
} /* end proc Get_Time() */
