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drivers/rtt_rtc: implement rtc_get_time_ms()

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RTC on RTT usually runs at a frequency greater than 1 Hz, so sub-second
precision is available.
Add a function to get the current RTC timestamp together with it's sub-second
component.
This commit is contained in:
Benjamin Valentin 2021-04-19 13:56:57 +02:00 committed by Benjamin Valentin
parent 0397cab91c
commit dcebc7d480
3 changed files with 33 additions and 0 deletions
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13
drivers/include/periph/rtc.h
View File

@ -90,6 +90,19 @@ int rtc_set_time(struct tm *time);
*/ */
int rtc_get_time(struct tm *time); int rtc_get_time(struct tm *time);
/**
* @brief Get current RTC time with sub-second component.
* Requires the `periph_rtc_ms` feature.
*
* @param[out] time Pointer to the struct to write the time to.
* @param[out] ms Pointer to a variable to hold the microsecond
* component of the current RTC time.
*
* @return 0 for success
* @return -1 an error occurred
*/
int rtc_get_time_ms(struct tm *time, uint16_t *ms);
/** /**
* @brief Set an alarm for RTC to the specified value. * @brief Set an alarm for RTC to the specified value.
* *

2
drivers/rtt_rtc/Makefile.features Normal file
View File

@ -0,0 +1,2 @@
FEATURES_PROVIDED += periph_rtc
FEATURES_PROVIDED += periph_rtc_ms

18
drivers/rtt_rtc/rtt_rtc.c
View File

@ -28,6 +28,7 @@
#include "periph/rtc.h" #include "periph/rtc.h"
#include "periph/rtt.h" #include "periph/rtt.h"
#include "timex.h"
#define ENABLE_DEBUG 0 #define ENABLE_DEBUG 0
#include "debug.h" #include "debug.h"
@ -40,6 +41,7 @@
#define TICKS(x) ( (x) * RTT_SECOND) #define TICKS(x) ( (x) * RTT_SECOND)
#define SECONDS(x) (_RTT(x) / RTT_SECOND) #define SECONDS(x) (_RTT(x) / RTT_SECOND)
#define SUBSECONDS(x) (_RTT(x) % RTT_SECOND)
/* Place counter in .noinit section if no backup RAM is available. /* Place counter in .noinit section if no backup RAM is available.
This means the date is undefined at cold boot, but will likely still This means the date is undefined at cold boot, but will likely still
@ -133,6 +135,22 @@ int rtc_set_time(struct tm *time)
return 0; return 0;
} }
int rtc_get_time_ms(struct tm *time, uint16_t *ms)
{
uint32_t prev = rtc_now;
/* repeat calculation if an alarm triggered in between */
do {
uint32_t now = rtt_get_counter();
uint32_t tmp = _rtc_now(now);
rtc_localtime(tmp, time);
*ms = (SUBSECONDS(now) * MS_PER_SEC) / RTT_SECOND;
} while (prev != rtc_now);
return 0;
}
int rtc_get_time(struct tm *time) int rtc_get_time(struct tm *time)
{ {
uint32_t prev = rtc_now; uint32_t prev = rtc_now;