/**
* @brief Update CSR register with the measured LSI frequency.
* @par Note on the APR calculation:
* A is the integer part of LSIFreqkHz/4 and x the decimal part.
* x <= A/(1+2A) is equivalent to A >= x(1+2A) and also to 4A >= 4x(1+2A) [F1]
* but we know that A + x = LSIFreqkHz/4 ==> 4x = LSIFreqkHz-4A
* so [F1] can be written :
* 4A >= (LSIFreqkHz-4A)(1+2A)
* @param LSIFreqHz Low Speed RC frequency measured by timer (in Hz).
* @retval None
* @par Required preconditions:
* - BEEP must be disabled to avoid unwanted interrupts.
*/
void BEEP_LSICalibrationConfig(uint32_t LSIFreqHz)
{
uint16_t lsifreqkhz;
uint16_t A;
/* Check parameter */
assert_param(IS_LSI_FREQUENCY_OK(LSIFreqHz));
lsifreqkhz = (uint16_t)(LSIFreqHz / 1000); /* Converts value in kHz */
/* Calculation of BEEPER calibration value */
BEEP->CSR &= (uint8_t)(~BEEP_CSR_BEEPDIV); /* Clear bits */
A = (uint16_t)(lsifreqkhz >> 3U); /* Division by 8, keep integer part only */
if ((8U * A) >= ((lsifreqkhz - (8U * A)) * (1U + (2U * A))))
{
BEEP->CSR |= (uint8_t)(A - 2U);
}
else
{
BEEP->CSR |= (uint8_t)(A - 1U);
}
}
/**
* @brief Update APR register with the measured LSI frequency.
* @par Note on the APR calculation:
* A is the integer part of lsifreqkhz/4 and x the decimal part.
* x <= A/(1+2A) is equivalent to A >= x(1+2A) and also to 4A >= 4x(1+2A) [F1]
* but we know that A + x = lsifreqkhz/4 ==> 4x = lsifreqkhz-4A
* so [F1] can be written :
* 4A >= (lsifreqkhz-4A)(1+2A)
* @param[in] LSIFreqHz Low Speed RC frequency measured by timer (in Hz).
* @retval None
* @par Required preconditions:
* - AWU must be disabled to avoid unwanted interrupts.
*/
void AWU_LSICalibrationConfig(u32 LSIFreqHz)
{
u16 lsifreqkhz = 0x0;
u16 A = 0x0;
/* Check parameter */
assert_param(IS_LSI_FREQUENCY_OK(LSIFreqHz));
lsifreqkhz = (u16)(LSIFreqHz / 1000); /* Converts value in kHz */
/* Calculation of AWU calibration value */
A = (u16)(lsifreqkhz >> 2U); /* Division by 4, keep integer part only */
if ((4U * A) >= ((lsifreqkhz - (4U * A)) * (1U + (2U * A))))
{
AWU->APR = (u8)(A - 2U);
}
else
{
AWU->APR = (u8)(A - 1U);
}
/* Set the MR bit to load the new value to the prescalers */
AWU->CSR |= AWU_CSR_MR;
}
