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STM32 LPT optimisation #5862

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Merged
merged 1 commit into from
Jan 18, 2018
Merged

STM32 LPT optimisation #5862

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11 changes: 2 additions & 9 deletions targets/TARGET_STM/lp_ticker.c
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Original file line number Diff line number Diff line change
Expand Up @@ -292,15 +292,8 @@ void lp_ticker_init(void)

uint32_t lp_ticker_read(void)
{
uint32_t usecs = 0;
time_t time = 0;

do {
time = rtc_read();
usecs = rtc_read_subseconds();
} while (time != rtc_read());

return (time * 1000000) + usecs;
uint32_t usecs = rtc_read_us();
return usecs;
}

void lp_ticker_set_interrupt(timestamp_t timestamp)
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30 changes: 28 additions & 2 deletions targets/TARGET_STM/rtc_api.c
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Expand Up @@ -36,8 +36,12 @@
static RTC_HandleTypeDef RtcHandle;

#if DEVICE_LOWPOWERTIMER && !MBED_CONF_TARGET_LOWPOWERTIMER_LPTIM

#define GET_TICK_PERIOD(VALUE) (2048 * 1000000 / VALUE) /* 1s / SynchPrediv value * 2^11 (value to get the maximum precision value with no u32 overflow) */

static void (*irq_handler)(void);
static void RTC_IRQHandler(void);
static uint32_t lp_TickPeriod_us = GET_TICK_PERIOD(4095); /* default SynchPrediv value = 4095 */
#endif /* DEVICE_LOWPOWERTIMER && !MBED_CONF_TARGET_LOWPOWERTIMER_LPTIM */

void rtc_init(void)
Expand Down Expand Up @@ -123,6 +127,10 @@ void rtc_init(void)
RtcHandle.Init.OutPutType = RTC_OUTPUT_TYPE_OPENDRAIN;
#endif /* TARGET_STM32F1 */

#if DEVICE_LOWPOWERTIMER && !MBED_CONF_TARGET_LOWPOWERTIMER_LPTIM
lp_TickPeriod_us = GET_TICK_PERIOD(RtcHandle.Init.SynchPrediv);
#endif

if (HAL_RTC_Init(&RtcHandle) != HAL_OK) {
error("RTC initialization failed");
}
Expand Down Expand Up @@ -309,9 +317,27 @@ static void RTC_IRQHandler(void)
}
}

uint32_t rtc_read_subseconds(void)
uint32_t rtc_read_us(void)
{
return 1000000.f * ((double)((RTC->PRER & RTC_PRER_PREDIV_S) - RTC->SSR) / ((RTC->PRER & RTC_PRER_PREDIV_S) + 1));
RTC_TimeTypeDef timeStruct = {0};
RTC_DateTypeDef dateStruct = {0};

RtcHandle.Instance = RTC;
HAL_RTC_GetTime(&RtcHandle, &timeStruct, RTC_FORMAT_BIN);

/* Reading RTC current time locks the values in calendar shadow registers until Current date is read
to ensure consistency between the time and date values */
HAL_RTC_GetDate(&RtcHandle, &dateStruct, RTC_FORMAT_BIN);

if (timeStruct.SubSeconds > timeStruct.SecondFraction) {
/* SS can be larger than PREDIV_S only after a shift operation. In that case, the correct
time/date is one second less than as indicated by RTC_TR/RTC_DR. */
timeStruct.Seconds -= 1;
}
uint32_t RTCTime = timeStruct.Seconds + timeStruct.Minutes * 60 + timeStruct.Hours * 60 * 60;
uint32_t Time_us = ((timeStruct.SecondFraction - timeStruct.SubSeconds) * lp_TickPeriod_us) >> 11;

return (RTCTime * 1000000) + Time_us ;
}

void rtc_set_wake_up_timer(uint32_t delta)
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6 changes: 3 additions & 3 deletions targets/TARGET_STM/rtc_api_hal.h
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Expand Up @@ -51,11 +51,11 @@ extern "C" {
#define RTC_CLOCK LSI_VALUE
#endif

/** Read the subsecond register.
/** Read RTC time with subsecond precision.
*
* @return The remaining time as microseconds (0-999999)
* @return Time is microsecond
*/
uint32_t rtc_read_subseconds(void);
uint32_t rtc_read_us(void);

/** Program a wake up timer event in delta microseconds.
*
Expand Down