Kinetis RTC driver.

RTC is clocked by a 32.768 kHz clock.

Please note the manual of your MCU or SiP for the clock setting for the RTC module. After initialization Time Seconds Register (TSR) increments once a second. The TSR (also TAR) value will be converted to the struct tm and back with the help of stdlib functions that are defined in time.h. The driver supports alarm, it is stored in the Time Alarm Registers (TAR) and the unit is seconds.

RTC configuration example (for periph_conf.h)

#define RTC_DEV             RTC
#define RTC_UNLOCK()        (SIM->SCGC6 |= (SIM_SCGC6_RTC_MASK))

Optional settings to configure internal load capacitors (see reference manual):

#define RTC_LOAD_CAP_BITS   0