在lpc1778/1788上实现
/******************************************************************************************************** * FunctionName   : GetSecondTime()
* Description    : 日期格式转化为unix time
* EntryParameter :
* ReturnValue    :
********************************************************************************************************/
unsigned long GetSecondTime(void)
{
    uint16_t rYear,i,Cyear=0;
    uint8_t rMon,rDay,rHour,rMin,rSec;
    unsigned long CountDay = 0;
    rSec =(uint8_t)((LPC_RTC->SEC)&0x7f);
    rMin =(uint8_t)((LPC_RTC->MIN)&0x7f);
    rHour = ((LPC_RTC->HOUR) & 0x3f);
    rDay = ((LPC_RTC->DOM) & 0x3f);
    rMon = ((LPC_RTC->MONTH) & 0x1f);
    rYear = ((LPC_RTC->YEAR));
 
    for(i = 1970; i < rYear; i++)
    {
      if(((i%4==0) && (i%100!=0)) || (i%400==0))  Cyear++;
  }
    CountDay = Cyear * 366 + (rYear-1970-Cyear) * 365;
  for(i=1; i   {
    if((i==2) && (((rYear%4==0)&&(rYear%100!=0)) || (rYear%400==0)))
            CountDay += 29;
    else
      CountDay += DayOfMon[i-1];
  }
  CountDay += (rDay-1);
  CountDay = CountDay*SECOND_OF_DAY + (unsigned long)rHour*3600 + (unsigned long)rMin*60 + rSec;
    CountDay = CountDay - 8*3600;//北京时间转化为世界时间
  return CountDay;
}
/********************************************************************************************************
* FunctionName   : GetDateTimeFromSecond()
* Description    : unix time转化为常用格式
* EntryParameter :
* ReturnValue    :
********************************************************************************************************/
void GetDateTimeFromSecond(unsigned long lSec, TIME_T *tTime)
{
    uint16 i,j,iDay;
  unsigned long lDay;
    lSec = lSec + 8*3600;//转换为北京时间
 
  lDay = lSec / SECOND_OF_DAY;        
  lSec = lSec % SECOND_OF_DAY;
  i = 1970;
  while(lDay > 365)
  {
        if(((i%4==0)&&(i%100!=0)) || (i%400==0))//闰年
            lDay -= 366;
    else
      lDay -= 365;
    i++;
  }
  if((lDay == 365) && !(((i%4==0)&&(i%100!=0)) || (i%400==0)))
  {
    lDay -= 365;
    i++;
  }
  tTime->year = i;//年份
  for(j=0;j<12;j++)  
  {
        if((j==1) && (((i%4==0)&&(i%100!=0)) || (i%400==0)))
            iDay = 29;
    else
      iDay = DayOfMon[j];
    if(lDay >= iDay) lDay -= iDay;
    else break;
    }
    tTime->month = j+1;
    tTime->day = lDay+1;
    tTime->hour = ((lSec / 3600))%24;
    tTime->min = (lSec % 3600) / 60;
    tTime->sec = (lSec % 3600) % 60;
}