MIC - Microphone Driver (ADC)
BSP > Thunderboard Sense BSP

Detailed Description

Driver for the Knowles SPV1840LR5H-B MEMS Microphone.

Functions

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

Error Codes

#define MIC_OK 0

Macro Definition Documentation

#define MIC_OK   0

No errors

Definition at line 58 of file mic.h .

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 189 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 262 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 250 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 287 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.

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 93 of file mic.c .

References ADC_Init() , ADC_INIT_DEFAULT , ADC_InitScan() , ADC_INITSCAN_DEFAULT , ADC_PrescaleCalc() , ADC_TimebaseCalc() , adcInit() , adcRef2V5 , BOARD_micEnable() , CMU_ClockEnable() , CMU_ClockFreqGet() , CMU_ClockSelectSet() , cmuClock_ADC0 , cmuClock_AUX , cmuClock_LFA , cmuClock_PRS , cmuSelect_LFXO , DMADRV_AllocateChannel() , DMADRV_Init() , ECODE_EMDRV_DMADRV_OK , ADC_Init_TypeDef::prescale , PRS_SourceAsyncSignalSet() , ADC_InitScan_TypeDef::prsEnable , ADC_InitScan_TypeDef::prsSel , ADC_InitScan_TypeDef::reference , and ADC_Init_TypeDef::timebase .

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 326 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 215 of file mic.c .

References DMADRV_PeripheralMemory() , dmadrvDataSize2 , and dmadrvPeripheralSignal_ADC0_SCAN .