How to calculate date,month and year ?

[antonius]

Posted on January 08, 2014 at 08:35

Guys,

How to calculate date,month and year ? from RTC_GetCounter function,

I saw :

uint32_t RTC_GetCounter(void)

{

  uint16_t tmp = 0;

  tmp = RTC->CNTL;

  return (((uint32_t)RTC->CNTH << 16 ) | tmp) ;

}

I've done :

 /* Load the Counter value */

 Tmp = RTC_GetCounter();

 /* Load the Counter value */

 Tmp = RTC_GetCounter();

 /* Compute day */

 WEEKDAY = (Tmp / 86400)%7;

 /* Compute date */

 DATE = (Tmp / 86400)%360;

/* Compute month */

 MONTH = (Tmp / 2629743)%12;

 

 /* Compute year */

YEAR = (Tmp / 31556926)+1970;

Please correct me .....

Any clues ?

thanks

[trevor23]

Posted on January 08, 2014 at 10:38

No ,I'd advise that you don't do this as you will get into lots of issues with leap years etc.. Use gmtime function (ideally thread safe version gmtime_r) from time library supplied with your tools (time.h). Read this: http://www.cplusplus.com/reference/ctime/

Google gmtime and mktime (and time.h) as this is a well discussed topic on the web. E.g.

#include <
time.h
>
struct tm tm_time;
time_t t_time;
t_time = RTC_GetCounter();
gmtime_r( &t_time, &tm_time );

Ask better questions like what your overall aim is not specifics that are going down a dead end anyway. And please stop creating new threads with no reference to old threads that relate to the same issue. Let's have one thread with better questions.

[antonius]

Posted on January 09, 2014 at 05:20

Where can I download time.h ?

[antonius]

Posted on January 09, 2014 at 05:32

I made :

 struct tm utcTimeSnapshot;

  time_t Tmp;

 /* Load the Counter value */

 Tmp = RTC_GetCounter();

 utcTimeSnapshot = *gmtime(&Tmp);

How can I extract, date,month,year, hour,minute,second ?

[Tesla DeLorean]

Posted on January 09, 2014 at 05:57

 struct tm *utcTimeSnapshot;

 time_t Tmp;

 /* Load the Counter value */

 Tmp = RTC_GetCounter();

 utcTimeSnapshot = gmtime(&Tmp); // it returns a pointer

Then utcTimeSnapshot->tm_hour, tm_year, etc

[Tesla DeLorean]

Posted on January 09, 2014 at 06:02

Also, be aware the reason you read the value twice is so you can actually COMPARE the value, to make sure it doesn't change, ie at a tick boundary

If it changes you should read it again until it doesn't, nominally one additional read.

[antonius]

Posted on January 09, 2014 at 06:31

I still read the value on second, not in the exact value, for example Wednesday is still on 134218199, how can I change it to a readable value for human ?

It's stable and easier with

Tmp = RTC_GetCounter();

 

 

 utcTimeSnapshot = localtime(&Tmp);

uint32_t /*Tmp,*/THH,TMM,TSS,WEEKDAY,DATE,MONTH,YEAR;

DATE = utcTimeSnapshot->tm_mday;

 sprintf(date,''%02d'',DATE);

  lcd_string(date);lcd_string(''-'');

[leventeyigel52]

Posted on January 09, 2014 at 09:46

// Define g_DateStructVar that contain Day,Month,Year,Hour,Minute

  Ans use this function .  

void CalculateDateTime(uint32_t t)

{

   

  const unsigned int daysInMonth [] = { 31,28,31,30,31,30,31,31,30,31,30,31 }; //has to be const or compiler compaints

  int d,m;

 

  unsigned int ss,mm,hh,yOff;

  ss = t % 60;

  t /= 60;

  mm = t % 60;

  t /= 60;

  hh = t % 24;

  unsigned int days = t / 24;

  unsigned int leap;

  for (yOff = 0; ; ++yOff) {

    leap = yOff % 4 == 0;

    if (days < 365 + leap)

      break;

    days -= 365 + leap;

  }  

  

  unsigned int daysPerMonth =0;

  for ( m = 1; ; ++m) {

    daysPerMonth = daysInMonth [m - 1];

    if (leap && m == 2)

      ++daysPerMonth;

    if (days < daysPerMonth)

      break;

    days -= daysPerMonth;

  }

  d = days + 1;

  g_DateStructVar.Day = d ;  

  g_DateStructVar.Month = m ;

  g_DateStructVar.Year = yOff + 1970 ;

  

  g_DateStructVar.Minutes = mm ; 

  g_DateStructVar.Seconds = ss ;

  g_DateStructVar.Hours = hh ; 

  

}

[Tesla DeLorean]

Posted on January 09, 2014 at 12:29

I still read the value on second, not in the exact value, for example Wednesday is still on 134218199, how can I change it to a readable value for human ?

Does it return a NULL pointer?

Does the library code you're using actually support gmtime() properly? Step into it, look at a disassembly.