Hi All,
I want to set the RTC time to the current time and date without hard-coding it.
I tried to use the function time() and ctime() defined in time.h, but I read that time() is a semihosted function (http://www.keil.com/support/man/docs/armlib/armlib_chr1359122861930.htm)
#include <time.h> time_t rawtime; char buffer[50] ={0}; time(&rawtime); sprintf (buffer, "%s", ctime(&rawtime) );
So if I include time(&rawtime), then the program stops with BKPT 0xAB (indicating semihosting) and if I don't include it then the buffer displays 00:00 1 Jan 1970.
So my question is, how do I write the retarget.c to use the time function? I read a lot of examples on retargeting printf, but can't find anything on time().
Or what is the normal way of setting the current date/time?
Thank you.
Note that time() doesn't set any time. It's just intended to retrieve time.
If you have an RTC that ticks a variable very second, and zero is the Unix epoch of 1970-01-01 00:00, then you can just write your own time:
time_t time(time_t* t) { time_t tmp = my_magical_rtc_tick_value; if (t) *t = tmp; return tmp; }
If the RTC maybe can generate an interrupt pulse every second and is interfaced using for example Maxim/Dallas one-wire protocol, then you need to write code that can write a clock value to the RTC, and that on program start can retrieve the current time. Then an interrupt handler that can increment a one-second tick variable.
If you have an internal RTC in the processor, then you might even read out the time from the RTC on every call to time() - but you may then have to use mktime() to convert from broken-down year, month, day, hour, min, sec into the epoch tick value that time() is expected to return.
Thanks for the reply, I think I'm not very clear on my question...
The my_magical_rtc_tick_value is exactly what I'm trying to get at.
So I will have to program multiple chips at different times with the same code, but I want their RTC value to reflect what the ACTUAL time is at the moment it is being programmed (according to the PC anyway).
I have the rtc_read function as follows
time_t rtc_read(void) { RTC_DateTypeDef dateStruct; RTC_TimeTypeDef timeStruct; struct tm timeinfo; hrtc.Instance = RTC; // Read actual date and time HAL_RTC_GetTime(&hrtc, &timeStruct, FORMAT_BIN); // Read time first! HAL_RTC_GetDate(&hrtc, &dateStruct, FORMAT_BIN); // Setup a tm structure based on the RTC timeinfo.tm_wday = dateStruct.WeekDay; timeinfo.tm_mon = dateStruct.Month - 1; timeinfo.tm_mday = dateStruct.Date; timeinfo.tm_year = dateStruct.Year + 100; timeinfo.tm_hour = timeStruct.Hours; timeinfo.tm_min = timeStruct.Minutes; timeinfo.tm_sec = timeStruct.Seconds; // Convert to timestamp time_t t = mktime(&timeinfo); return t; }
and in main I can read it and it gives me the hardcoded value that I put in.
rawtime = rtc_read(); sprintf (buffer, "%s", ctime(&rawtime) );
I saw SYS_TIME (0x11) and it seems to be what I need, but I can't find any example code and have no idea how to use it.
Any ideas?
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