PDM microphones

lib_xua supports input from up to 8 PDM microphones although this is extensible.

PDM microphone support is provided via lib_mic_array. Settings for PDM microphones are controlled with the defines in Table 24.

Table 24 PDM defines

Define	Description	Default
XUA_NUM_PDM_MICS	The number of mic outputs to enable (0 for disabled). This enables compilation of the PDM to PCM code also.	0 (disabled)
XUA_NUM_PDM_MICS_IN	The number of mic input lines. This defines the width of the PDM data port and must be at least XUA_NUM_PDM_MICS.	XUA_NUM_PDM_MICS
XUA_PDM_MIC_INDEX	Defines which starting input channel the mics map to	0
XUA_PDM_MIC_USE_PDM_ISR	Define as 1 to enable merging of the PDM receive task and decimation task into a single thread using an ISR	1 (Run PDM RX service as an ISR)
XUA_PDM_MIC_USE_DDR	Define as 1 to enable two microphones sharing a single data line (DDR mode)	1 (DDR mode)

Note

mic array task always runs on the tile defined by XUA_MIC_PDM_TILE_NUM, the value of which is inferred from the PORT_PDM_CLK port define in the application XN file.

Note

Currently the only supported sampling rates for the PDM microphones are 16kHz, 32kHz and 48kHz.

Note

Setting XUA_PDM_MIC_USE_PDM_ISR is only recommended for PDM mic counts below 8.

Please see the PDM Microphones section for further details.