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 mics to enable (0 for disabled). This enables compilation of the PDM to PCM code also.	0 (disabled)
PDM_MIC_INDEX	Defines which starting input channel the mics map to	0
XUA_PDM_MIC_FREQ	Defines the PCM output sample rate of lib_mic_array	None (must be defined)
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	0 (use separate threads for PDM and decimation)

Note

Currently only a single, fixed sample rate is supported for the PDM microphones

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.