MEMS Microphone Functions

Detailed Description

MEMS microphone driver and support functions.

DO_NOT_INCLUDE_WITH_DOXYGEN

Functions
void	MIC_deInit (void)
	Powers down the MEMS microphone stops the ADC and frees up the DMA channel. More...
float	MIC_getMean (void)
	Calculates the average value of the samples in the buffer. More...
uint16_t *	MIC_getSampleBuffer (void)
	Gets the sample buffer. More...
float	MIC_getSoundLevel (float *var)
	Calculates the sound level. More...
uint32_t	MIC_init (uint32_t fs, uint16_t *buffer, size_t len)
	Initializes MEMS microphone and sets up the DMA, ADC and clocking. More...
bool	MIC_isBusy (void)
	Checks if the microphone is in use. More...
void	MIC_start (uint32_t nSamples)
	Starts taking samples using DMA from the microphone. More...

Function Documentation

void MIC_deInit

(

void

)

Powers down the MEMS microphone stops the ADC and frees up the DMA channel.

Returns

None

Definition at line 186 of file mic.c.

References BOARD_micEnable(), DMADRV_FreeChannel(), and PRS_SourceAsyncSignalSet().

float MIC_getMean

(

void

)

Calculates the average value of the samples in the buffer.

Returns

The mean value of the samples in the buffer

Definition at line 267 of file mic.c.

Referenced by MIC_getSoundLevel().

uint16_t * MIC_getSampleBuffer

(

void

)

Gets the sample buffer.

Returns

Returns a pointer to the sample buffer

Definition at line 253 of file mic.c.

float MIC_getSoundLevel

(

float *

var

)

Calculates the sound level.

Parameters

[out]

var

The variance of the samples

Returns

The sound level in dB

Definition at line 294 of file mic.c.

References MIC_getMean().

uint32_t MIC_init	(	uint32_t	fs,
		uint16_t *	buffer,
		size_t	len
	)

Initializes MEMS microphone and sets up the DMA, ADC and clocking.

DO_NOT_INCLUDE_WITH_DOXYGEN

Parameters

[in]	fs	The desired sample rate in Hz
[in]	buffer	Pointer to the sample buffer to store the ADC data
[in]	len	The size of the sample buffer

Returns

Returns zero on OK, non-zero otherwise

Definition at line 87 of file mic.c.

References ADC0, ADC_Init(), ADC_INIT_DEFAULT, ADC_InitScan(), ADC_INITSCAN_DEFAULT, ADC_PrescaleCalc(), ADC_TimebaseCalc(), adcInit(), adcRef2V5, BOARD_micEnable(), CMU, CMU_ClockEnable(), CMU_ClockFreqGet(), CMU_ClockSelectSet(), CMU_CTRL_CLKOUTSEL1_LFXOQ, cmuClock_ADC0, cmuClock_AUX, cmuClock_LFA, cmuClock_PRS, cmuSelect_LFXO, LETIMER_Init_TypeDef::comp0Top, DMADRV_AllocateChannel(), DMADRV_Init(), ECODE_EMDRV_DMADRV_OK, LETIMER_Init_TypeDef::enable, LETIMER_CompareSet(), LETIMER_Init(), LETIMER_INIT_DEFAULT, LETIMER_RepeatSet(), letimerUFOAPulse, MIC_ADC_CLOCK_FREQ, ADC_Init_TypeDef::prescale, PRS_SourceAsyncSignalSet(), ADC_InitScan_TypeDef::prsEnable, ADC_InitScan_TypeDef::prsSel, ADC_InitScan_TypeDef::reference, ADC_Init_TypeDef::timebase, and LETIMER_Init_TypeDef::ufoa0.

bool MIC_isBusy

(

void

)

Checks if the microphone is in use.

Returns

Returns true if the DMA is busy taking microphone samples

Definition at line 336 of file mic.c.

void MIC_start

(

uint32_t

nSamples

)

Starts taking samples using DMA from the microphone.

Parameters

[in]

nSamples

The number of the samples to take

Returns

None

Definition at line 214 of file mic.c.

References ADC0, DMADRV_PeripheralMemory(), dmadrvDataSize2, and dmadrvPeripheralSignal_ADC0_SCAN.