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.