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Hi guys,
I have the following code for a Freescale KL25Z-based Cortex-M0+, which attempts to generate hours, minutes, seconds etc from an epoch time that I'm extracting from the RTC:
#include <MKL25Z4.H> #include <time.h> time_t epochTimeSnapshot; struct tm utcTimeSnapshot; void TimeTakeSnapshot( void ) { epochTimeSnapshot = RTC->TSR; utcTimeSnapshot = *gmtime( &epochTimeSnapshot ); }
I'm compiling this file against C90 and am not using microlib. I've not attempted to customise any of the time.h functions, as I am not using any that are processor independent, just gmtime().
I can confirm that from the RTC, the value 0x51CC6DF8 is being placed into epochTimeSnapshot, which is a correct epoch time from a few days ago as far as I understand it. The issue is that following the execution of gmtime, the utcTimeSnapshot structure is being populated as follows:
tm_sec = 0x1FFFFDA0 tm_min = 0x00000339 tm_hour = 0x00000341 tm_mday = 0x00000343 tm_mon = 0x00000000 tm_year = 0x00000000 tm_wday = 0x00000000 tm_yday = 0x00000000 tm_isdst = 0x00000000
These results are clearly not correct, however I can't determine why this is, as I don't have access to the source of the gmtime function.
Has anyone else experienced any issues like this before? Am I perhaps missing something?
Any advice is much appreciated.
Many thanks
Code doesn't look right, try
#include <MKL25Z4.H> #include <time.h> time_t epochTimeSnapshot; struct tm * utcTimeSnapshot; void TimeTakeSnapshot( void ) { epochTimeSnapshot = RTC->TSR; utcTimeSnapshot = gmtime( &epochTimeSnapshot ); // look at utcTimeSnapshot->tm_min }
Although rare, that code is valid, I actually had your example first but modified it to match one I had found whilst trying to resolve the issue, to reduce the number of potential mistakes.
I've further looked into the issue and it appears it may very well be a bug, as substituting the code with the following works perfectly:
#include <MKL25Z4.H> #include <time.h> time_t epochTimeSnapshot; struct tm utcTimeSnapshot; void TimeTakeSnapshot( void ) { epochTimeSnapshot = RTC->TSR; localtime_r( &epochTimeSnapshot, &utcTimeSnapshot ); }
I will have to explore this a little more when I have time and see if I can produce a simple test case.