/***************************************************************************//**
* @brief
* Get clock frequency of the BURTC.
*
* @return
* The current frequency in Hz.
******************************************************************************/
uint32_t BURTC_ClockFreqGet(void)
{
uint32_t clkSel;
uint32_t clkDiv;
uint32_t frequency;
clkSel = BURTC->CTRL & _BURTC_CTRL_CLKSEL_MASK;
clkDiv = (BURTC->CTRL & _BURTC_CTRL_PRESC_MASK) >> _BURTC_CTRL_PRESC_SHIFT;
switch (clkSel)
{
/** Ultra low frequency (1 kHz) clock */
case BURTC_CTRL_CLKSEL_ULFRCO:
if (_BURTC_CTRL_PRESC_DIV1 == clkDiv)
{
frequency = 2000; /* 2KHz when clock divisor is 1. */
}
else
{
frequency = SystemULFRCOClockGet(); /* 1KHz when divisor is different
from 1. */
}
break;
/** Low frequency RC oscillator */
case BURTC_CTRL_CLKSEL_LFRCO:
frequency = SystemLFRCOClockGet() / (1 << clkDiv); /* freq=32768/2^clkDiv */
break;
/** Low frequency crystal osciallator */
case BURTC_CTRL_CLKSEL_LFXO:
frequency = SystemLFXOClockGet() / (1 << clkDiv); /* freq=32768/2^clkDiv */
break;
default:
/* No clock selected for BURTC. */
frequency = 0;
}
return frequency;
}
/**************************************************************************//**
* Initialize and start RTC.
*****************************************************************************/
static void StartRTC( void )
{
/* Enable LE */
CMU->HFCORECLKEN0 |= CMU_HFCORECLKEN0_LE;
/* Enable LFRCO for RTC */
CMU->OSCENCMD = CMU_OSCENCMD_LFRCOEN;
/* Setup LFA to use LFRCRO */
CMU->LFCLKSEL = CMU_LFCLKSEL_LFA_LFRCO;
/* Enable RTC */
CMU->LFACLKEN0 = CMU_LFACLKEN0_RTC;
/* Clear interrupt flags */
RTC->IFC = RTC_IFC_COMP1 | RTC_IFC_COMP0 | RTC_IFC_OF;
/* 250 ms wakeup time */
RTC->COMP0 = ( PIN_LOOP_INTERVAL * SystemLFRCOClockGet() ) / 1000;
/* Enable Interrupts on COMP0 */
RTC->IEN = RTC_IEN_COMP0;
/* Enable RTC interrupts */
NVIC_EnableIRQ(RTC_IRQn);
/* Enable RTC */
RTC->CTRL = RTC_CTRL_COMP0TOP | RTC_CTRL_DEBUGRUN | RTC_CTRL_EN;
}
