ulx3s/Lobby

#include <stdio.h>
#include <stdlib.h>

#define I2C_SLAVE 0x703
#define O_RDWR 2

int i2c_rtc;

void rtc_open(int addr)
{
  i2c_rtc = open("/dev/i2c-0", O_RDWR);
  ioctl(i2c_rtc, I2C_SLAVE, addr);
}

void rtc_read(unsigned char *buf, int reg, int n)
{
  buf[0] = reg;
  write(i2c_rtc, buf, 1);
  read(i2c_rtc, buf, n);
}

void i2cdemo(void)
{
  int i;
  unsigned char buf[7];
  // mask for BCD          SEC   MIN   HOUR  WKDAY DAY   MONTH YEAR
  unsigned char mask[7] = {0x7F, 0x7F, 0x3F, 0x07, 0x3F, 0x1F, 0xFF};

  rtc_read(buf, 0, sizeof(buf));
  for(i = sizeof(buf)-1; i >= 0; i--)
    printf(" %02x", buf[i] & mask[i]);
  printf("\n");
}

int main(int argc, char *argv[])
{
  int i;
  rtc_open(0x6F);
  for(i = 0; i < 60; i++)
  {
    i2cdemo();
    sleep(1);
  }
  return 0;
}
root@buildroot:/home/root/rtc# ./a.out 
 20 09 22 02 21 14 27
 20 09 22 02 21 14 28
 20 09 22 02 21 14 29
 20 09 22 02 21 14 30
 20 09 22 02 21 14 31