/***************************************************************************//**
* @brief
* Init pulse counter.
*
* @details
* This function will configure the pulse counter. The clock selection is
* configured as follows, depending on operational mode:
*
* @li #pcntModeOvsSingle - Use LFACLK.
* @li #pcntModeExtSingle - Use external PCNTn_S0 pin.
* @li #pcntModeExtQuad - Use external PCNTn_S0 pin.
*
* Notice that the LFACLK must be enabled in all modes, since some basic setup
* is done with this clock even if external pin clock usage mode is chosen.
* The pulse counter clock for the selected instance must also be enabled
* prior to init.
*
* Notice that pins used by the PCNT module must be properly configured
* by the user explicitly through setting the ROUTE register, in order for
* the PCNT to work as intended.
*
* Writing to CNT will not occur in external clock modes (EXTCLKQUAD and
* EXTCLKSINGLE) because the external clock rate is unknown. The user should
* handle it manually depending on the application
*
* TOPB is written for all modes but in external clock mode it will take
* 3 external clock cycles to sync to TOP
*
*
* @note
* Initializing requires synchronization into the low frequency domain. This
* may cause some delay.
*
* @param[in] pcnt
* Pointer to PCNT peripheral register block.
*
* @param[in] init
* Pointer to initialization structure used to initialize.
******************************************************************************/
void PCNT_Init(PCNT_TypeDef *pcnt, const PCNT_Init_TypeDef *init)
{
unsigned int inst;
uint32_t tmp;
EFM_ASSERT(PCNT_REF_VALID(pcnt));
/* Map pointer to instance */
inst = PCNT_Map(pcnt);
#if (defined (_EFM32_TINY_FAMILY) || defined (_EFM32_GIANT_FAMILY))
/* Selecting the PRS channels for the PRS input sources of the PCNT. These are
* written with a Read-Modify-Write sequence in order to keep the value of the
* input enable bits which can be modified using PCNT_PRSInputEnable(). */
tmp = pcnt->INPUT & ~(_PCNT_INPUT_S0PRSSEL_MASK | _PCNT_INPUT_S1PRSSEL_MASK);
tmp |= ((uint32_t)init->s0PRS << _PCNT_INPUT_S0PRSSEL_SHIFT) |
((uint32_t)init->s1PRS << _PCNT_INPUT_S1PRSSEL_SHIFT);
pcnt->INPUT = tmp;
#endif
/* Build CTRL setting, except for mode */
tmp = 0;
if (init->negEdge)
{
tmp |= PCNT_CTRL_EDGE_NEG;
}
if (init->countDown)
{
tmp |= PCNT_CTRL_CNTDIR_DOWN;
}
if (init->filter)
{
tmp |= PCNT_CTRL_FILT;
}
#if (defined (_EFM32_TINY_FAMILY) || defined (_EFM32_GIANT_FAMILY))
if (init->hyst)
{
tmp |= PCNT_CTRL_HYST;
}
if (init->s1CntDir)
{
tmp |= PCNT_CTRL_S1CDIR;
}
/* Configure counter events for regular and auxiliary counter. */
tmp |= init->cntEvent << _PCNT_CTRL_CNTEV_SHIFT;
tmp |= init->auxCntEvent << _PCNT_CTRL_AUXCNTEV_SHIFT;
#endif
/* Reset pulse counter while changing clock source. The reset bit */
/* is asynchronous, we don't have to check for SYNCBUSY. */
BITBAND_Peripheral(&(pcnt->CTRL), _PCNT_CTRL_RSTEN_SHIFT, 1);
/* Select LFACLK to clock in control setting */
CMU_PCNTClockExternalSet(inst, false);
/* Handling depends on whether using external clock or not. */
switch (init->mode)
{
case pcntModeExtSingle:
case pcntModeExtQuad:
tmp |= init->mode << _PCNT_CTRL_MODE_SHIFT;
/* In most cases, the SYNCBUSY bit is set due to reset bit set, and waiting
* for asynchronous reset bit is strictly not necessary.
* But in theory, other operations on CTRL register may have been done
* outside this function, so wait. */
PCNT_Sync(pcnt, PCNT_SYNCBUSY_CTRL);
/* Enable PCNT Clock Domain Reset. The PCNT must be in reset before changing
* the clock source to an external clock */
pcnt->CTRL = PCNT_CTRL_RSTEN;
/* Wait until CTRL write synchronized into LF domain. */
PCNT_Sync(pcnt, PCNT_SYNCBUSY_CTRL);
/* Change to external clock BEFORE disabling reset */
CMU_PCNTClockExternalSet(inst, true);
/* Write to TOPB. If using external clock TOPB will sync to TOP at the same
* time as the mode. This will insure that if the user chooses to count
* down, the first "countable" pulse will make CNT go to TOP and not 0xFF
* (default TOP value). */
pcnt->TOPB = init->top;
/* This bit has no effect on rev. C and onwards parts - for compatibility */
pcnt->CMD = PCNT_CMD_LTOPBIM;
/* Write the CTRL register with the configurations.
* This should be written after TOPB in the eventuality of a pulse between
* these two writes that would cause the CTRL register to be synced one
* clock cycle earlier than the TOPB. */
pcnt->CTRL = tmp;
/* There are no syncs for TOP, CMD or CTRL because the clock rate is unknown
* and the program could stall
* These will be synced within 3 clock cycles of the external clock /
* For the same reason CNT cannot be written here. */
break;
/* pcntModeDisable */
/* pcntModeOvsSingle */
default:
/* No need to set disabled mode if already disabled. */
if ((pcnt->CTRL & _PCNT_CTRL_MODE_MASK) != PCNT_CTRL_MODE_DISABLE)
{
/* Set control to disabled mode, leave reset on until ensured disabled.
* We don't need to wait for CTRL SYNCBUSY completion here, it was
* triggered by reset bit above, which is asynchronous. */
pcnt->CTRL = tmp | PCNT_CTRL_MODE_DISABLE | PCNT_CTRL_RSTEN;
/* Wait until CTRL write synchronized into LF domain before proceeding
* to disable reset. */
PCNT_Sync(pcnt, PCNT_SYNCBUSY_CTRL);
}
/* Disable reset bit, counter should now be in disabled mode. */
BITBAND_Peripheral(&(pcnt->CTRL), _PCNT_CTRL_RSTEN_SHIFT, 0);
/* Set counter and top values as specified. */
PCNT_CounterTopSet(pcnt, init->counter, init->top);
/* Enter oversampling mode if selected. */
if (init->mode == pcntModeOvsSingle)
{
PCNT_Sync(pcnt, PCNT_SYNCBUSY_CTRL);
pcnt->CTRL = tmp | (init->mode << _PCNT_CTRL_MODE_SHIFT);
}
break;
}
}
/***************************************************************************//**
* @brief
* Init pulse counter.
*
* @details
* This function will configure the pulse counter. The clock selection is
* configured as follows, depending on operational mode:
*
* @li #pcntModeOvsSingle - Use LFACLK.
* @li #pcntModeExtSingle - Use external PCNTn_S0 pin.
* @li #pcntModeExtQuad - Use external PCNTn_S0 pin.
*
* Notice that the LFACLK must be enabled in all modes, since some basic setup
* is done with this clock even if external pin clock usage mode is chosen.
* The pulse counter clock for the selected instance must also be enabled
* prior to init.
*
* Notice that pins used by the PCNT module must be properly configured
* by the user explicitly through setting the ROUTE register, in order for
* the PCNT to work as intended.
*
* @note
* Initializing requires synchronization into the low frequency domain. This
* may cause some delay.
*
* @param[in] pcnt
* Pointer to PCNT peripheral register block.
*
* @param[in] init
* Pointer to initialization structure used to initialize.
******************************************************************************/
void PCNT_Init(PCNT_TypeDef *pcnt, PCNT_Init_TypeDef *init)
{
unsigned int inst;
uint32_t tmp;
EFM_ASSERT(PCNT_REF_VALID(pcnt));
/* Map pointer to instance */
inst = PCNT_Map(pcnt);
/* Build CTRL setting, except for mode */
tmp = 0;
if (init->negEdge)
{
tmp |= PCNT_CTRL_EDGE_NEG;
}
if (init->countDown)
{
tmp |= PCNT_CTRL_CNTDIR_DOWN;
}
if (init->filter)
{
tmp |= PCNT_CTRL_FILT;
}
/* Reset pulse counter while changing clock source. The reset bit */
/* is asynchronous, we don't have to check for SYNCBUSY. */
BITBAND_Peripheral(&(pcnt->CTRL), _PCNT_CTRL_RSTEN_SHIFT, 1);
/* Select LFACLK to clock in control setting */
CMU_PCNTClockExternalSet(inst, false);
/* Handling depends on whether using external clock or not. */
switch (init->mode)
{
case pcntModeExtSingle:
case pcntModeExtQuad:
tmp |= init->mode << _PCNT_CTRL_MODE_SHIFT;
/* In most cases, the SYNCBUSY bit is set due to reset bit set, */
/* and waiting for asynchronous reset bit is strictly not necessary. */
/* But in theory, other operations on CTRL reg may have been done */
/* outside this func, so wait. */
PCNT_Sync(pcnt, PCNT_SYNCBUSY_CTRL);
pcnt->CTRL = tmp | PCNT_CTRL_RSTEN;
/* Wait until CTRL write synchronized into LF domain. */
PCNT_Sync(pcnt, PCNT_SYNCBUSY_CTRL);
/* Do dummy write to ensure fully activated in LF domain before */
/* switching to external clock, may require one additional clock. */
pcnt->CTRL = tmp | PCNT_CTRL_RSTEN;
PCNT_Sync(pcnt, PCNT_SYNCBUSY_CTRL);
/* Change to external clock BEFORE disabling reset */
CMU_PCNTClockExternalSet(inst, true);
/* Disable reset bit, it can be done without waiting for SYNCBUSY bit. */
/* (Notice that this will set SYNCBUSY bit for CTRL register even if */
/* bit is asynchronous. The SYNCBUSY bit will remain set until external */
/* pulses completes synchronization and clears bit.) */
BITBAND_Peripheral(&(pcnt->CTRL), _PCNT_CTRL_RSTEN_SHIFT, 0);
/* TOP and CNT registers have been reset, but we should not set them */
/* since external clock rate is unknown. Handling depends on application. */
break;
/* pcntModeDisable */
/* pcntModeOvsSingle */
default:
/* No need to set disabled mode if already disabled */
if ((pcnt->CTRL & _PCNT_CTRL_MODE_MASK) != PCNT_CTRL_MODE_DISABLE)
{
/* Set control to disabled mode, leave reset on until ensured disabled. */
/* We don't need to wait for CTRL SYNCBUSY completion here, it was */
/* triggered by reset bit above, which is asynchronous. */
pcnt->CTRL = tmp | PCNT_CTRL_MODE_DISABLE | PCNT_CTRL_RSTEN;
/* Wait until CTRL write synchronized into LF domain before proceeding */
/* to disable reset. */
PCNT_Sync(pcnt, PCNT_SYNCBUSY_CTRL);
}
/* Disable reset bit, counter should now be in disabled mode. */
BITBAND_Peripheral(&(pcnt->CTRL), _PCNT_CTRL_RSTEN_SHIFT, 0);
/* Set counter and top values as specified */
PCNT_CounterTopSet(pcnt, init->counter, init->top);
/* Enter oversampling mode if selected. */
if (init->mode == pcntModeOvsSingle)
{
PCNT_Sync(pcnt, PCNT_SYNCBUSY_CTRL);
pcnt->CTRL = tmp | (init->mode << _PCNT_CTRL_MODE_SHIFT);
}
break;
}
}
