FREQM Interface

Driver API for FREQM (plib_freqm.h) More...

Typedefs
typedef void(*	FREQM_CALLBACK_HANDLER) (uint8_t flags)
	FREQM interrupt callback function type.

Enumerations
enum	FREQM_STATUS { FREQM_STATUS_BUSY , FREQM_STATUS_OVERFLOW }
	FREQM Status bits. More...

Functions
void	FREQM_Enable (void)
	Enables the FREQM peripheral.
void	FREQM_Disable (void)
	Disables the FREQM peripheral.
void	FREQM_SetRefNum (uint8_t refnum)
	Set REFNUM.
void	FREQM_SoftwareReset (void)
	Reset the FREQM peripheral.
bool	FREQM_StartMeasurement (void)
	Start the frequency measurement.
uint32_t	FREQM_GetFrequency (uint32_t ref_clk)
	Get the frequency value.
bool	FREQM_GetStatus (FREQM_STATUS status)
	Check the FREQM status.
void	FREQM_ClearOverflowStatus (void)
	Clear the overflow status bit.
void	FREQM_EnableInterrupt (void)
	Enable the Measurement Done Interrupt.
void	FREQM_DisableInterrupt (void)
	Disable the Measurement Done Interrupt.
void	FREQM_ClearInterruptFlag (void)
	Clear the Measurement Done Interrupt Flag.
void	FREQM_SetCallbackHandler (FREQM_CALLBACK_HANDLER callback)
	Register a callback function for FREQM interrupt.

Description

Driver API for FREQM (plib_freqm.h)

Usage Example

The following example demonstrates typical usage of the FREQM peripheral:

 
 #include "plib_freqm.h"
 #include <pic32c.h>
 #include <stdint.h>
 
 /* Example callback function for freqm interrupts */
 void freqmCallback(uint8_t flags)
 {
    static uint32_t cfg_ref_clk = 32768UL;
    static uint32_t freq;
    (void)flags;
     if (FREQM_GetStatus(FREQM_STATUS_OVERFLOW))
     {
        //Clear overflow status and try reducing the refnum and start a new measurement.
     }
     else
     {
         /*Read the frequency value*/
         freq = FREQM_GetFrequency(cfg_ref_clk);
         (void)freq;
     }
 }
 
int32_t configure_freqm(void)
 {
    /* Configuration constants */
    uint8_t refnum = 128;
 
    /* Perform a software reset to ensure the FREQM is in a known state */
    FREQM_SoftwareReset();
 
    /*Set the number of reference clock cycles*/
    FREQM_SetRefNum(refnum);
 
    /* Register the user callback handler for FREQM interrupts */
    FREQM_SetCallbackHandler(&freqmCallback);  
 
    /* Enable FREQM interrupt */ 
    FREQM_EnableInterrupt();
 
    /*Enable the FREQM peripheral*/
    FREQM_Enable();
 
    /* Enable NVIC interrupt handling for the FREQM module */
    NVIC_EnableIRQ(FREQM_IRQn);
 
    /*Start the frequency measurement*/
    (void)FREQM_StartMeasurement();
    
    return 0;
 }

Typedef Documentation

FREQM_CALLBACK_HANDLER

typedef void(* FREQM_CALLBACK_HANDLER) (uint8_t flags)

FREQM interrupt callback function type.

Enumeration Type Documentation

FREQM_STATUS

enum FREQM_STATUS

FREQM Status bits.

Enumerator
FREQM_STATUS_BUSY
FREQM_STATUS_OVERFLOW

Function Documentation

FREQM_ClearInterruptFlag()

void FREQM_ClearInterruptFlag

(

void

)

Clear the Measurement Done Interrupt Flag.

FREQM_ClearOverflowStatus()

void FREQM_ClearOverflowStatus

(

void

)

Clear the overflow status bit.

FREQM_Disable()

void FREQM_Disable

(

void

)

Disables the FREQM peripheral.

FREQM_DisableInterrupt()

void FREQM_DisableInterrupt

(

void

)

Disable the Measurement Done Interrupt.

FREQM_Enable()

void FREQM_Enable

(

void

)

Enables the FREQM peripheral.

FREQM_EnableInterrupt()

void FREQM_EnableInterrupt

(

void

)

Enable the Measurement Done Interrupt.

FREQM_GetFrequency()

uint32_t FREQM_GetFrequency

(

uint32_t

ref_clk

)

Get the frequency value.

Parameters

ref_clk

Reference clock frequency

FREQM_GetStatus()

bool FREQM_GetStatus

(

FREQM_STATUS

status

)

Check the FREQM status.

Parameters

status

Status to be checked

Returns

true if the status bit is set, false otherwise.

FREQM_SetCallbackHandler()

void FREQM_SetCallbackHandler

(

FREQM_CALLBACK_HANDLER

callback

)

Register a callback function for FREQM interrupt.

Parameters

callback

Pointer to the callback function.

FREQM_SetRefNum()

void FREQM_SetRefNum

(

uint8_t

refnum

)

Set REFNUM.

Parameters

refnum

Set the number of reference clock cycles

FREQM_SoftwareReset()

void FREQM_SoftwareReset

(

void

)

Reset the FREQM peripheral.

FREQM_StartMeasurement()

bool FREQM_StartMeasurement

(

void

)

Start the frequency measurement.