I am working on STM32F107 to read MP34DT05-A mems mic on I2S. I have tried any configuration setting with `pdm2pcm.c` and i2s.c but nothing shows the expected result.
The expected result is positive int value. This is what i did so far:
- i2s3 (SPI3) set to master RX mode, standar msb, format 16b extended with audio freq 8k.
- DMA2 channel 1 halfword, circular and very high priority.
- PDM filter set to LSB, big endian, decimation by 64.
Calling the function:
usb_printf("\nMEAS MIC..");
__HAL_RCC_CRC_CLK_ENABLE();
HAL_I2S_Receive_DMA(&hi2s3, pdm_buff, 16);
usb_printf("\nPDM BUFF: ");
usb_printf(pdm_buff);
while (1) {
uint16_t *pcm_out;
uint16_t *pdm_out;
memcpy(cbuff, pdm_buff, sizeof(pdm_buff));
PDM_Filter(&cbuff[0], &pcm_buff[0], &PDM1_filter_handler);
usb_printf("\ncbuff: 0x%04X ", cbuff[0]);
usb_printf("pcm_buff: 0x%04X ", pcm_buff[0]);
usb_printf("pcm_buff int: %d", pcm_buff[0]);
}
delay_ms(500);
And the result is something like this:
pcm_buff: 0xFFFF828F pcm_buff int: -32113
pcm_buff: 0xFFFFA2E3 pcm_buff int: -23837
pcm_buff: 0xFFFFB379 pcm_buff int: -19591
Am I missing something? Or is there any missed configuration?
#STM32F1 #I2S #[MEMS Microphones]
