Posted on December 22, 2013 at 14:55Hello.
I'm using mp45dt02 mic on the discovery board and just forwarding data to cs43l22. For sampling freq 16k is working fine, but if I want higher Fs, it doesn't work anymore. I'm only hearing beeping/scratching from dac. Playing some 48k sound from flash works fine, so cs43l22 must be ok. I must be doing something wrong with the mic.
I can provide cs43l22 code and/or hex files if someone will be interested.
Here is the code for mp45dt02:
&sharpinclude <stdint.h>
&sharpinclude ''stm32f4xx.h''
&sharpinclude ''stm32f4xx_rcc.h''
&sharpinclude ''stm32f4xx_gpio.h''
&sharpinclude ''stm32f4xx_spi.h''
&sharpinclude ''pdm_filter.h''
&sharpinclude ''queve.h''
//sampling frequency
&sharpdefine FS 16000
//PDM decimation factor
&sharpdefine DECIMATION 64
//clock for mic
&sharpdefine I2S_CLK ((FS*DECIMATION)/(16*2))
//uint16_t array length for filter input buffer
&sharpdefine MIC_IN_BUF_SIZE ((((FS/1000)*DECIMATION)/8)/2)
//uint16_t array length for filter output buffer
&sharpdefine MIC_OUT_BUF_SIZE (FS/1000)
static PDMFilter_InitStruct pdm_filter;
static uint16_t mic_in_buf[MIC_IN_BUF_SIZE];
static uint16_t mic_out_buf[MIC_OUT_BUF_SIZE];
static uint32_t mic_buf_index;
void mp45dt02_init(){
RCC_AHB1PeriphClockCmd(RCC_AHB1Periph_CRC, ENABLE);
pdm_filter.LP_HZ=8000;
pdm_filter.HP_HZ=10;
pdm_filter.Fs=FS;
pdm_filter.Out_MicChannels=1;
pdm_filter.In_MicChannels=1;
PDM_Filter_Init(&pdm_filter);
//MP45DT02 CLK-PB10
RCC_AHB1PeriphClockCmd(RCC_AHB1Periph_GPIOB, ENABLE);
GPIO_InitTypeDef gpio;
gpio.GPIO_Pin=GPIO_Pin_10;
gpio.GPIO_Mode=GPIO_Mode_AF;
gpio.GPIO_OType=GPIO_OType_PP;
gpio.GPIO_PuPd=GPIO_PuPd_NOPULL;
gpio.GPIO_Speed=GPIO_Speed_50MHz;
GPIO_Init(GPIOB, &gpio);
GPIO_PinAFConfig(GPIOB, GPIO_PinSource10, GPIO_AF_SPI2);
//MP45DT02 DOUT-PC3
RCC_AHB1PeriphClockCmd(RCC_AHB1Periph_GPIOC, ENABLE);
gpio.GPIO_Pin=GPIO_Pin_3;
gpio.GPIO_Mode=GPIO_Mode_AF;
gpio.GPIO_OType=GPIO_OType_PP;
gpio.GPIO_PuPd=GPIO_PuPd_NOPULL;
gpio.GPIO_Speed=GPIO_Speed_50MHz;
GPIO_Init(GPIOC, &gpio);
GPIO_PinAFConfig(GPIOC, GPIO_PinSource3, GPIO_AF_SPI2);
NVIC_InitTypeDef nvic;
nvic.NVIC_IRQChannel = SPI2_IRQn;
nvic.NVIC_IRQChannelPreemptionPriority = 1;
nvic.NVIC_IRQChannelSubPriority = 0;
nvic.NVIC_IRQChannelCmd = ENABLE;
NVIC_Init(&nvic);
//I2S2 config
RCC_APB1PeriphClockCmd(RCC_APB1Periph_SPI2, ENABLE);
RCC_PLLI2SCmd(ENABLE);
while(!RCC_GetFlagStatus(RCC_FLAG_PLLI2SRDY));
I2S_InitTypeDef i2s;
i2s.I2S_AudioFreq=I2S_CLK;
i2s.I2S_Standard=I2S_Standard_LSB;
i2s.I2S_DataFormat=I2S_DataFormat_16b;
i2s.I2S_CPOL=I2S_CPOL_High;
i2s.I2S_Mode=I2S_Mode_MasterRx;
i2s.I2S_MCLKOutput=I2S_MCLKOutput_Disable;
I2S_Init(SPI2, &i2s);
I2S_Cmd(SPI2, ENABLE);
}
void mp45dt02_start(){
SPI_I2S_ITConfig(SPI2, SPI_I2S_IT_RXNE, ENABLE);
}
void SPI2_IRQHandler(){
if(SPI_GetITStatus(SPI2, SPI_I2S_IT_RXNE)){
uint16_t sample=SPI_I2S_ReceiveData(SPI2);
mic_in_buf[mic_buf_index++]=HTONS(sample);
if(mic_buf_index == MIC_IN_BUF_SIZE){
mic_buf_index=0;
PDM_Filter_64_LSB((uint8_t *)mic_in_buf, mic_out_buf, 40, &pdm_filter);
uint32_t i;
for(i=0; i<MIC_OUT_BUF_SIZE; i++){
enqueve(mic_out_buf[i]);
}
}
}
}
Thanks.
#stm32f4discovery-mp45dt02
