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STM32 RTC Init minor update #6723

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Merged
merged 1 commit into from
Apr 25, 2018
Merged

STM32 RTC Init minor update #6723

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19 changes: 6 additions & 13 deletions targets/TARGET_STM/rtc_api.c
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Original file line number Diff line number Diff line change
Expand Up @@ -53,7 +53,11 @@ void rtc_init(void)
__HAL_RCC_PWR_CLK_ENABLE();
HAL_PWR_EnableBkUpAccess();

#if DEVICE_LOWPOWERTIMER
if ( (rtc_isenabled()) && ((RTC->PRER & RTC_PRER_PREDIV_S) == PREDIV_S_VALUE) ) {
#else /* DEVICE_LOWPOWERTIMER */
if (rtc_isenabled()) {
#endif /* DEVICE_LOWPOWERTIMER */
return;
}

Expand Down Expand Up @@ -107,19 +111,8 @@ void rtc_init(void)
RtcHandle.Init.AsynchPrediv = RTC_AUTO_1_SECOND;
#else /* TARGET_STM32F1 */
RtcHandle.Init.HourFormat = RTC_HOURFORMAT_24;

/* PREDIV_A : 7-bit asynchronous prescaler */
#if DEVICE_LOWPOWERTIMER && !MBED_CONF_TARGET_LOWPOWERTIMER_LPTIM
/* PREDIV_A is set to a small value to improve the SubSeconds resolution */
/* with a 32768Hz clock, PREDIV_A=7 gives a precision of 244us */
RtcHandle.Init.AsynchPrediv = 7;
#else
/* PREDIV_A is set to the maximum value to improve the consumption */
RtcHandle.Init.AsynchPrediv = 0x007F;
#endif
/* PREDIV_S : 15-bit synchronous prescaler */
/* PREDIV_S is set in order to get a 1 Hz clock */
RtcHandle.Init.SynchPrediv = RTC_CLOCK / (RtcHandle.Init.AsynchPrediv + 1) - 1;
RtcHandle.Init.AsynchPrediv = PREDIV_A_VALUE;
RtcHandle.Init.SynchPrediv = PREDIV_S_VALUE;
RtcHandle.Init.OutPut = RTC_OUTPUT_DISABLE;
RtcHandle.Init.OutPutPolarity = RTC_OUTPUT_POLARITY_HIGH;
RtcHandle.Init.OutPutType = RTC_OUTPUT_TYPE_OPENDRAIN;
Expand Down
14 changes: 14 additions & 0 deletions targets/TARGET_STM/rtc_api_hal.h
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Expand Up @@ -51,6 +51,20 @@ extern "C" {
#define RTC_CLOCK LSI_VALUE
#endif

/* PREDIV_A : 7-bit asynchronous prescaler */
/* PREDIV_S : 15-bit synchronous prescaler */
/* PREDIV_S is set in order to get a 1 Hz clock */
#if DEVICE_LOWPOWERTIMER && !MBED_CONF_TARGET_LOWPOWERTIMER_LPTIM
/* PREDIV_A is set to a small value to improve the SubSeconds resolution */
/* with a 32768Hz clock, PREDIV_A=7 gives a precision of 244us */
#define PREDIV_A_VALUE 7
#else /* DEVICE_LPTICKER && !MBED_CONF_TARGET_LPTICKER_LPTIM */
/* PREDIV_A is set to the maximum value to improve the consumption */
#define PREDIV_A_VALUE 127
#endif /* DEVICE_LPTICKER && !MBED_CONF_TARGET_LPTICKER_LPTIM */

#define PREDIV_S_VALUE RTC_CLOCK / (PREDIV_A_VALUE + 1) - 1

/** Read RTC time with subsecond precision.
*
* @return Time is microsecond
Expand Down