[XU316] Mic Array Library and >2 mics

[alex4d1]

Hi all,

I have a RTOS application running on XU316 using the mic array library with 2 mics in DDR configuration connected to a 1-bit MIC DATA port.
I modified the decimator stages of the mic array library to sample at 96ksps. This works perfectly.

Now I would like to add more microphones. I switched to a 4-bit port and reconfigured the mic array library to use 8 microphones in DDR configuration, but now rtos_mic_array_rx() call does not return anymore.
If I change the configuration to use a 4-bit port but only use 2 microphones the problem goes away.

This makes me think this is not a problem of the port width but the mic array library itself. The mic array library has only so many parameters, so I am confused on what I am doing wrong.
Does anyone have any suggestions?

Here is snippet of the cmake file of my BSP (4-bit port, only 2 mics):

Code: Select all

    set(MIC_MAPPING "0, 1")

    target_compile_definitions(projects_board_support_config_xcore_ai_explorer_custom
        INTERFACE
            PLATFORM_SUPPORTS_TILE_0=1
            PLATFORM_SUPPORTS_TILE_1=1
            PLATFORM_SUPPORTS_TILE_2=0
            PLATFORM_SUPPORTS_TILE_3=0
            USB_TILE_NO=0
            USB_TILE=tile[USB_TILE_NO]

            MIC_ARRAY_CONFIG_MCLK_FREQ=24576000
            MIC_ARRAY_CONFIG_PDM_FREQ=3072000
            MIC_ARRAY_CONFIG_SAMPLES_PER_FRAME=64
            MIC_ARRAY_CONFIG_USE_DDR=1
            MIC_ARRAY_CONFIG_MIC_COUNT=2
            MIC_ARRAY_CONFIG_MIC_INPUT=8
            MIC_ARRAY_CONFIG_INPUT_MAPPING={${MIC_MAPPING}}
            MIC_ARRAY_CONFIG_USE_DC_ELIMINATION=1
            MIC_ARRAY_CONFIG_CLOCK_BLOCK_A=XS1_CLKBLK_1
            MIC_ARRAY_CONFIG_CLOCK_BLOCK_B=XS1_CLKBLK_2
            MIC_ARRAY_CONFIG_PORT_MCLK=PORT_MCLK_IN
            MIC_ARRAY_CONFIG_PORT_PDM_CLK=PORT_PDM_CLK
            MIC_ARRAY_CONFIG_PORT_PDM_DATA=PORT_PDM_DATA
            # DEBUG_PRINT_ENABLE_RTOS_MIC_ARRAY=1
    )

My custom vanilla implementation:

Code: Select all

using TMicArray = mic_array::prefab::BasicMicArray<
                        MIC_ARRAY_CONFIG_MIC_COUNT,
                        MIC_ARRAY_CONFIG_SAMPLES_PER_FRAME,
                        MIC_ARRAY_CONFIG_USE_DC_ELIMINATION,
                        MIC_ARRAY_CONFIG_MIC_INPUT>;

TMicArray mics;


void ma_vanilla_init()
{
  unsigned input_mic_mapping[] = MIC_ARRAY_CONFIG_INPUT_MAPPING;
  _Static_assert(
        (sizeof(input_mic_mapping) / sizeof(unsigned)) == MIC_ARRAY_CONFIG_MIC_COUNT,
        "The number of elements in MIC_ARRAY_CONFIG_INPUT does not match MIC_ARRAY_CONFIG_MIC_COUNT"
  );
  
  mics.Init();
  mics.SetPort(pdm_res.p_pdm_mics);
  mics.PdmRx.MapChannels(input_mic_mapping);
  mic_array_resources_configure(&pdm_res, MIC_ARRAY_CONFIG_MCLK_DIVIDER);
  mic_array_pdm_clock_start(&pdm_res);
}

My XN file:

Code: Select all

            <!-- Mic related ports -->
            <Port Location="XS1_PORT_1G" Name="PORT_PDM_CLK"/>
            <Port Location="XS1_PORT_4B" Name="PORT_PDM_DATA"/>

And the calls to the mic array library:

Code: Select all

static void mics_init(void)
{
#if ON_TILE(MICARRAY_TILE_NO)
    rtos_mic_array_init(
            mic_array_ctx,
            (1 << appconfPDM_MIC_IO_CORE),
            RTOS_MIC_ARRAY_CHANNEL_SAMPLE);
#endif /* MIC_ARRAY */
}
...
static void mics_start(void)
{
#if ON_TILE(MICARRAY_TILE_NO)
    rtos_mic_array_start(
            mic_array_ctx,
            2 * MIC_ARRAY_CONFIG_SAMPLES_PER_FRAME,
            appconfPDM_MIC_INTERRUPT_CORE);
#endif /* MIC_ARRAY */
}
...
#ifndef appconfAUDIO_FRAME_LENGTH
#define appconfAUDIO_FRAME_LENGTH               (MIC_ARRAY_CONFIG_SAMPLES_PER_FRAME)
#endif /* appconfAUDIO_FRAME_LENGTH */

#ifndef appconfAUDIO_PIPELINE_CHANNELS
#define appconfAUDIO_PIPELINE_CHANNELS          (MIC_ARRAY_CONFIG_MIC_COUNT)
#endif /* appconfAUDIO_PIPELINE_CHANNELS */
...
int32_t input_audio_frames[appconfAUDIO_PIPELINE_CHANNELS][appconfAUDIO_FRAME_LENGTH];
int32_t frame_count = appconfAUDIO_FRAME_LENGTH;
...
frames_received = rtos_mic_array_rx(mic_array_ctx,
                        (int32_t**)input_audio_frames,
                        frame_count,
                        portMAX_DELAY);

Cheers
Alex