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fix[STM32][RTC]: Compute tv_usec from SecondFraction/SubSeconds and skip during shift pending

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Use the generic SecondFraction/SubSeconds formula when SSR/PRER are available.
If SHPF is present and a shift is pending, keep tv_usec at 0.
Platforms without SSR/PRER (e.g. F1) default to 0.
This commit is contained in:
wdfk-prog
2026-02-03 14:43:02 +08:00
committed by R b b666
parent 06e829b1b3
commit f9de290991
1 changed files with 25 additions and 4 deletions
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29
bsp/stm32/libraries/HAL_Drivers/drivers/drv_rtc.c
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@@ -10,6 +10,7 @@
* 2021-02-05 Meco Man fix the problem of mixing local time and UTC time
* 2021-07-05 iysheng implement RTC framework V2.0
* 2025-06-05 RCSN add local time conversion for get timeval and set stamp
* 0206-02-03 wdfk_prog compute tv_usec from SecondFraction/SubSeconds
*/
#include "board.h"
@@ -85,10 +86,30 @@ static rt_err_t stm32_rtc_get_timeval(struct timeval *tv)
#else
tv->tv_sec = timegm(&tm_new);
#endif
#if defined(SOC_SERIES_STM32H7)
tv->tv_usec = (255.0 - RTC_TimeStruct.SubSeconds * 1.0) / 256.0 * 1000.0 * 1000.0;
#endif
tv->tv_usec = 0U;
/* F1 RTC does not have SSR/PRER */
#if defined(RTC_SSR_SS) && defined(RTC_PRER_PREDIV_S)
/*
* You can use SubSeconds and SecondFraction (sTime structure fields
* returned) to convert SubSeconds value in second fraction ratio with
* time unit following generic formula:
* Second fraction ratio * time_unit =
* [(SecondFraction - SubSeconds) / (SecondFraction + 1)] * time_unit
* This conversion can be performed only if no shift operation is pending
* (ie. SHFP=0) when PREDIV_S >= SS
*/
#if defined(RTC_ISR_SHPF)
if (READ_BIT(RTC->ISR, RTC_ISR_SHPF) == 0U)
#endif /* RTC_ISR_SHPF */
{
uint32_t sf = RTC_TimeStruct.SecondFraction;
uint32_t ss = RTC_TimeStruct.SubSeconds;
if ((sf != 0U) && (ss <= sf))
{
tv->tv_usec = (uint32_t)(((sf - ss) * 1000000ULL) / (sf + 1U));
}
}
#endif /* defined(RTC_SSR_SS) && defined(RTC_PRER_PREDIV_S) */
return RT_EOK;
}