I hear about this technology, I read about it, I even see a bunch of MEMS microphones with PDM output. I can perfectly understand how it works (I have worked with DSP). However, I can't seem to make heads or tails regarding how do I deal with it in practice.
I expect that there would be Digital Signal Processors that have built-in (hardware-based) PDM inputs; I would even expect microcontrollers to have that (since MEMS microphones typically used for mobile devices seem to use PDM interface quite often).
However, I do a search in Digikey, and not a single one lists PDM among the included features or interfaces (not a single DSP, not a single MCU). I did find a PDM-to-I²S chip (in 8-pin BGA --- *ugh*) , but it doesn't make sens that that would be the only option --- in that case, I might as well get a microphone with I²S output!
I think I understand enough of the math that I would be able to implement in software a bit-banged PDM decoder --- however, I also understand enough to know that that is unthinkable in practice.
I guess my concrete question for the audience is: what's up with that?