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 43 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 174 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 247 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 235 of file mic.c.

float MIC_getSoundLevel ( float *  var)

Calculates the sound level.

Parameters
[out]varThe variance of the samples
Returns
The sound level in dB

Definition at line 272 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]fsThe desired sample rate in Hz
[in]bufferPointer to the sample buffer to store the ADC data
[in]lenThe size of the sample buffer
Returns
Returns zero on OK, non-zero otherwise

Definition at line 78 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, 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 311 of file mic.c.

void MIC_start ( uint32_t  nSamples)

Starts taking samples using DMA from the microphone.

Parameters
[in]nSamplesThe number of the samples to take
Returns
None

Definition at line 200 of file mic.c.

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