FMEAS: Frequency Measure Driver

Overview

The MCUXpresso SDK provides a peripheral driver for the Frequency Measure function of MCUXpresso SDK devices' SYSCON module.
It measures frequency of any on-chip or off-chip clock signal. The more precise and higher accuracy clock is selected as a reference clock. The resulting frequency is internally computed from the ratio of value of selected target and reference clock counters.

Frequency Measure Driver operation

INPUTMUX_AttachSignal() function has to be used to select reference and target clock signal sources.

FMEAS_StartMeasure() function starts the measurement cycle.

FMEAS_IsMeasureComplete() can be polled to check if the measurement cycle has finished.

FMEAS_GetFrequency() returns the frequency of the target clock. Frequency of the reference clock has to be provided as a parameter.

Typical use case

Refer to the driver examples codes located at <SDK_ROOT>/boards/<BOARD>/driver_examples/fmeas

Files
file	fsl_fmeas.h

Driver version
#define	FSL_FMEAS_DRIVER_VERSION   (MAKE_VERSION(2, 1, 0))
	Defines LPC Frequency Measure driver version 2.1.0. More...

FMEAS Functional Operation
static void	FMEAS_StartMeasure (FMEAS_SYSCON_Type *base)
	Starts a frequency measurement cycle. More...
static bool	FMEAS_IsMeasureComplete (FMEAS_SYSCON_Type *base)
	Indicates when a frequency measurement cycle is complete. More...
uint32_t	FMEAS_GetFrequency (FMEAS_SYSCON_Type *base, uint32_t refClockRate)
	Returns the computed value for a frequency measurement cycle. More...

Macro Definition Documentation

#define FSL_FMEAS_DRIVER_VERSION   (MAKE_VERSION(2, 1, 0))

Function Documentation

static void FMEAS_StartMeasure ( FMEAS_SYSCON_Type *  base )

inlinestatic

Parameters

base	: SYSCON peripheral base address.

Set the reference clock count cycle to 2^20 times

static bool FMEAS_IsMeasureComplete ( FMEAS_SYSCON_Type *  base )

inlinestatic

Parameters

base	: SYSCON peripheral base address.

Returns

true if a measurement cycle is active, otherwise false.

uint32_t FMEAS_GetFrequency	(	FMEAS_SYSCON_Type *	base,
		uint32_t	refClockRate
	)

Parameters

base	: SYSCON peripheral base address.
refClockRate	: Reference clock rate used during the frequency measurement cycle.

Returns

Frequency in Hz.