Posted on June 09, 2015 at 18:22
Hallo,
I am working on extracting the data from the MP45DT I used PDM filter function. I gave a beep sound to the microphone in the certain frequency, but I noticed that the captured raw data is not given as a sine wave.
#define SPI_Nr SPI2
#define DMA_SPI DMA1_Stream3
#define PDM_LENGTH 320
#define PCM_LENGTH 32
/*Private function--------------------------------------------------------------------*/
/* Temporary data sample in the DMA memory */
uint16_t AUDIO_SAMPLE_RX_MEM1 [PDM_LENGTH ]; //<
Array
of DMA MEM0 for double buffer
uint16_t AUDIO_SAMPLE_RX_MEM0 [PDM_LENGTH] ; //< Array of DMA MEM1 for double buffer
static uint32_t
AudioRecInited
=
0
; //Current state of the audio recorder interface initialization
PDMFilter_InitStruct Filter;
/* Main buffer pointer for the recorded data storing */
uint16_t* pAudioRecBuf; //< Pointer for Audio record for PDM data collect
uint16_t OutputBuffer0[PCM_LENGTH]; //< Output Buffer 0 after PDM
uint16_t OutputBuffer1[PCM_LENGTH]; //< Output Buffer 1 after PDM
void SignalReceive_Init(void)
{
/* Configure the SPI with 32KHz Audio frequency */
WaveRecord_SPI_Init();
/* Configure the DMA (double buffer) and interrupts */
WaveRecord_DMA_Init();
/* Filter LP & HP Init */
Filter.LP_HZ
=
32000
;
Filter.HP_HZ
=
10
;
Filter.Fs
=
32000
;
Filter.Out_MicChannels
=
1
;
Filter.In_MicChannels
=
1
;
PDM_Filter_Init((PDMFilter_InitStruct *)&Filter);
/* Set state of the audio recorder to initialized */
AudioRecInited
=
1
;
}// End of SignalReceive_Init()
void WaveRecord_SPI_Init(void)
{
/**************I2S2 Initialization ***************************/
I2S_InitTypeDef I2S_InitStructure;
SPI_I2S_DeInit(SPI_Nr);
I2S_InitStructure.I2S_AudioFreq
=
64000
;//I2S_AudioFreq_48k ; //< Audio is recorded from two channels, so this value must be twice the value in the PDM filter
I2S_InitStructure.I2S_Standard
=
I2S_Standard_LSB
;
I2S_InitStructure.I2S_DataFormat
=
I2S_DataFormat_16b
;
I2S_InitStructure.I2S_CPOL
=
I2S_CPOL_High
;
I2S_InitStructure.I2S_Mode
=
I2S_Mode_MasterRx
;
I2S_InitStructure.I2S_MCLKOutput
=
I2S_MCLKOutput_Disable
;
/* Initialize the I2S peripheral with the structure above */
I2S_Init(SPI_Nr, &I2S_InitStructure);
}// End of WaveRecord_SPI_Init()
void WaveRecord_DMA_Init(void)
{
//***** The DMA Configuration ****************//
DMA_InitTypeDef DMA_InitStructure;
//********* DMA init (DMA1, Channel0, Stream3)*********//
DMA_Cmd(DMA_SPI, DISABLE);
DMA_DeInit(DMA_SPI);
DMA_InitStructure.DMA_Channel
=
DMA_Channel_0
;
DMA_InitStructure.DMA_PeripheralBaseAddr = (uint32_t)&(SPI_Nr->DR);
DMA_InitStructure.DMA_Memory0BaseAddr = (uint32_t)AUDIO_SAMPLE_RX_MEM0;
DMA_InitStructure.DMA_DIR = DMA_DIR_PeripheralToMemory ;
DMA_InitStructure.DMA_BufferSize =PDM_LENGTH;
DMA_InitStructure.DMA_PeripheralInc = DMA_PeripheralInc_Disable;
DMA_InitStructure.DMA_MemoryInc = DMA_MemoryInc_Enable;
DMA_InitStructure.DMA_PeripheralDataSize = DMA_PeripheralDataSize_HalfWord;
DMA_InitStructure.DMA_MemoryDataSize = DMA_MemoryDataSize_HalfWord;
DMA_InitStructure.DMA_Mode = DMA_Mode_Circular;
DMA_InitStructure.DMA_Priority = DMA_Priority_Medium ;
DMA_InitStructure.DMA_FIFOMode = DMA_FIFOMode_Disable;
DMA_InitStructure.DMA_FIFOThreshold = DMA_FIFOThreshold_HalfFull;
DMA_InitStructure.DMA_MemoryBurst = DMA_MemoryBurst_Single;
DMA_InitStructure.DMA_PeripheralBurst = DMA_PeripheralBurst_Single;
DMA_Init(DMA_SPI, &DMA_InitStructure);
//*******Setup the Dual Buffer mode for the Rx DMA1 Stream 3 **********//
DMA_DoubleBufferModeConfig (DMA_SPI, (uint32_t)AUDIO_SAMPLE_RX_MEM1,DMA_Memory_1);
DMA_DoubleBufferModeCmd(DMA_SPI, ENABLE);
DMA_Init(DMA_SPI, &DMA_InitStructure);
//*********** Transfer complete interrupt enabling *************//
DMA_ITConfig(DMA_SPI, DMA_IT_TC, ENABLE);
//************** DMA enable***********************************//
DMA_Cmd(DMA_SPI, ENABLE);
}// End of WaveRecord_DMA_Init()
uint8_t SignalReceive_start(void)
{
/* Check if the interface has already been initialized */
/*Enable the I2S DMA */
SPI_I2S_DMACmd( SPI_Nr, SPI_I2S_DMAReq_Rx, ENABLE);
/* Enable the SPI peripheral */
I2S_Cmd(SPI_Nr, ENABLE);
/* Return 0 if all operations are OK */
return 0;
I2S_ISR_Indication=0;
}
void DMA1_Stream3_IRQHandler(void)
{
uint16_t volume;
volume = 64;
//**********Check the transfer complete event *********//
if (DMA_GetITStatus(DMA_SPI, DMA_IT_TCIF3)== SET)
{
DMA_ClearFlag(DMA_SPI, DMA_FLAG_TCIF3);
//GPIO_ToggleBits(GPIOD, GPIO_Pin_14);
if(DMA_GetCurrentMemoryTarget(DMA_SPI)==1) //
{
pAudioRecBuf=OutputBuffer0;
PDM_Filter_64_LSB((uint8_t *)AUDIO_SAMPLE_RX_MEM0,(uint16_t *)pAudioRecBuf, volume , (PDMFilter_InitStruct *)&Filter);
}
else
{
pAudioRecBuf=OutputBuffer1;
PDM_Filter_64_LSB((uint8_t *)AUDIO_SAMPLE_RX_MEM1,(uint16_t *)pAudioRecBuf, volume , (PDMFilter_InitStruct *)&Filter);
}
}
DMA_ClearITPendingBit(DMA_SPI, DMA_IT_HTIF3); ///< clear pending interrupt
} //< End of DMA1_Stream3_IRQHandler
Posted on June 10, 2015 at 02:06
Is there anything else I miss?
Thanks Clive1
I do the casting for converting the unsigned 16-Bit to signed 16-Bit. Is it correct?void DMA1_Stream3_IRQHandler(void)
{
uint16_t volume;
int16_t PCM_out[PCM_LENGTH];
volume = 50;
//**********Check the transfer complete event *********//
if (DMA_GetITStatus(DMA_SPI, DMA_IT_TCIF3)== SET)
{
DMA_ClearFlag(DMA_SPI, DMA_FLAG_TCIF3);
//GPIO_ToggleBits(GPIOD, GPIO_Pin_14);
if(DMA_GetCurrentMemoryTarget(DMA_SPI)==1) //
{
pAudioRecBuf=OutputBuffer0;
PDM_Filter_64_LSB((uint8_t *)AUDIO_SAMPLE_RX_MEM0,(uint16_t *)pAudioRecBuf, volume , (PDMFilter_InitStruct *)&Filter);
for(i=0;i < PCM_LENGTH;i++)
{
PCM_out[i]=(int16_t)OutputBuffer0[i]; //< Casting
}
}
else
{
pAudioRecBuf=OutputBuffer1;
PDM_Filter_64_LSB((uint8_t *)AUDIO_SAMPLE_RX_MEM1,(uint16_t *)pAudioRecBuf, volume , (PDMFilter_InitStruct *)&Filter);
for(i=0;i < PCM_LENGTH;i++)
{
PCM_out[i]=(int16_t)OutputBuffer1[i]; //< Casting
}
}
}
DMA_ClearITPendingBit(DMA_SPI, DMA_IT_HTIF3); ///< clear pending interrupt
} //< End of DMA1_Stream3_IRQHandler