Question
stereo recording with 2 MEMS mics using libPDMFilter
Posted on January 18, 2016 at 18:37
Hello everyone,
I have a STM32F4-Discovery board with an integrated MP45DT02 MEMS mic, and I've bought also anothere mic (an MP34DT01), I would like to record at the same time from the 2 mics. I'm able to record in RAM and playback the audio from the integrated mic, to do so, I've edited the example application ''Audio_playback_and_record'' (http://www.st.com/st-web-ui/static/active/en/resource/technical/document/application_note/DM00040802.pdf). To decode the pdm bitstream I use the libPDMFilter distributed with the example (its header is ''pdm_filter.h'')... The problem is that the only documentation I've found for that lib is this: http://www.st.com/st-web-ui/static/active/en/resource/technical/document/application_note/DM00040808.pdf ...But there are no hints on how to decode a stereo bitstream produced by 2 mics (the only thing that is said is that, in the bitstream, L/R channel's bytes must be interleaved)... I've tried a lot of configuration of all parameters but I still can't get the desired result... At the end I'm able to get one channel or the other for example: L channel ok, silence on the right channel. Or (switching the bytes) the opposite ...But I can't get both channel togheter. How to get L/R with libPDMFilter? Otherwise... Are there any serious documentation about that lib? Thank you very much! #pdm-stereo-mems-mic-libpdmfilter