130 lines
3.2 KiB
C
130 lines
3.2 KiB
C
//Mostly stolen from:
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//http://electronics.stackexchange.com/questions/98414/stm32f4-discovery-audio-sampling-above-16khz-not-working
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#include "mp45dt02.h"
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#include <stm32f4xx_rcc.h>
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#include <stm32f4xx_gpio.h>
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#include <stm32f4xx_spi.h>
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#include <pdm_filter.h>
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//Warning: uncommenting this uses my PDM filter,
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//which is pretty awful and slow.
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#define ST_PDM
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#ifdef ST_PDM
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static PDMFilter_InitStruct pdm_filter;
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#endif
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void InitMP45DT02()
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{
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//Have to enable this because the ST library expects it.
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RCC_AHB1PeriphClockCmd(RCC_AHB1Periph_CRC, ENABLE);
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#ifdef ST_PDM
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pdm_filter.LP_HZ=DFREQ*2; //??? This is wrong, but if I make it lower, it really cuts into my bandwidth.
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pdm_filter.HP_HZ=20;
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pdm_filter.Fs=FS;
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pdm_filter.Out_MicChannels=1;
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pdm_filter.In_MicChannels=1;
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PDM_Filter_Init(&pdm_filter);
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#endif
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//MP45DT02 CLK-PB10
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RCC_AHB1PeriphClockCmd(RCC_AHB1Periph_GPIOB, ENABLE);
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GPIO_InitTypeDef gpio;
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gpio.GPIO_Pin=GPIO_Pin_10;
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gpio.GPIO_Mode=GPIO_Mode_AF;
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gpio.GPIO_OType=GPIO_OType_PP;
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gpio.GPIO_PuPd=GPIO_PuPd_NOPULL;
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gpio.GPIO_Speed=GPIO_Speed_50MHz;
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GPIO_Init(GPIOB, &gpio);
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GPIO_PinAFConfig(GPIOB, GPIO_PinSource10, GPIO_AF_SPI2);
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//MP45DT02 DOUT-PC3
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RCC_AHB1PeriphClockCmd(RCC_AHB1Periph_GPIOC, ENABLE);
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gpio.GPIO_Pin=GPIO_Pin_3;
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gpio.GPIO_Mode=GPIO_Mode_AF;
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gpio.GPIO_OType=GPIO_OType_PP;
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gpio.GPIO_PuPd=GPIO_PuPd_NOPULL;
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gpio.GPIO_Speed=GPIO_Speed_2MHz;
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GPIO_Init(GPIOC, &gpio);
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GPIO_PinAFConfig(GPIOC, GPIO_PinSource3, GPIO_AF_SPI2);
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NVIC_InitTypeDef nvic;
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nvic.NVIC_IRQChannel = SPI2_IRQn;
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nvic.NVIC_IRQChannelPreemptionPriority = 1;
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nvic.NVIC_IRQChannelSubPriority = 0;
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nvic.NVIC_IRQChannelCmd = ENABLE;
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NVIC_Init(&nvic);
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RCC_PLLI2SCmd(ENABLE);
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//I2S2 config
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RCC_APB1PeriphClockCmd(RCC_APB1Periph_SPI2, ENABLE);
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I2S_InitTypeDef i2s;
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i2s.I2S_AudioFreq=I2S_FS;
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i2s.I2S_Standard=I2S_Standard_LSB;
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i2s.I2S_DataFormat=I2S_DataFormat_16b;
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i2s.I2S_CPOL=I2S_CPOL_High;
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i2s.I2S_Mode=I2S_Mode_MasterRx;
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i2s.I2S_MCLKOutput=I2S_MCLKOutput_Disable;
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I2S_Init(SPI2, &i2s);
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I2S_Cmd(SPI2, ENABLE);
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//Start
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SPI_I2S_ITConfig(SPI2, SPI_I2S_IT_RXNE, ENABLE);
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}
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void SPI2_IRQHandler(void)
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{
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#ifdef ST_PDM
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static uint8_t InternalBufferSize;
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static uint16_t InternalBuffer[MIC_IN_BUF_SIZE];
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#else
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static int32_t IIRBuffer;
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static int32_t IIRLowpass;
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static int8_t IIRPl;
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#endif
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if(SPI_GetITStatus(SPI2, SPI_I2S_IT_RXNE))
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{
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uint16_t app = SPI_I2S_ReceiveData(SPI2);
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#ifdef ST_PDM
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InternalBuffer[InternalBufferSize++] = HTONS(app);
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if (InternalBufferSize >= MIC_IN_BUF_SIZE)
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{
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int i;
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uint16_t audioRec[MIC_OUT_BUF_SIZE];
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InternalBufferSize = 0;
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//got 64 samples of 16bit => 16 samples of output
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PDM_Filter_64_LSB((uint8_t *)InternalBuffer,
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(uint16_t *)audioRec,
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VOLUME, (PDMFilter_InitStruct *)&pdm_filter);
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for( i = 0; i < MIC_OUT_BUF_SIZE; i++ )
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{
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GotSample( audioRec[i] );
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}
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}
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#else
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int i;
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for( i = 0; i < 16; i++ )
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{
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IIRBuffer = IIRBuffer - (IIRBuffer/1024) + (((1<<i)&app)?1:-1)*256;
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}
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IIRPl++;
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if( IIRPl == 4 )
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{
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GotSample( IIRBuffer - IIRLowpass );
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IIRPl = 0;
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}
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#endif
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}
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}
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