I2s PDM implementation?

[kyleSpaulus]

Hi,

Is there work on adding PDM for the i2s protocol?

Looking through MEMS microphone options, most output PDM. When going into ultra sonic range even more so. I am in need of this protocol for a project involving 20 +KHz range.

Is it straight forward to decode the signal through the i2s peripheral using Philips protocol? Has anyone tried this with success?

PDM to i2s would be cool to solve this need. I understand PDM is implemented already in esp-IDF. (PDM Rx Mode) https://docs.espressif.com/projects/esp-idf/en/stable/esp32/api-reference/peripherals/i2s.html

//Kyle

P.S I chatGPT'd everything about PDM decoding and have no idea what I am talking about. It appears that a solution would be to add an Audio Codec and convert PDM to i2s forcing to design my own PCB to solve this in a reasonable way. Looking for an easier solution before going here with software. OR is there a nice breakout board with a straight forward audio codec?

With kind regards

[bjoernQ]

Out of curiosity: Which MEMS microphone do you intend to use? e.g. the popular INMP411 is Philips standard and pretty much anything else I can find is - but the INMP411 is not suitable for ultra sonic frequencies

Adding support for more modes shouldn't be too hard - PRs welcome

[kyleSpaulus]

Hi Bjoern,

I was thinking about Knowels Zero-Height SiSonic - Up to 80KHz https://www.micbooster.com/datasheets/spu0410lr5h-qb.pdf.

Further research is pointed more towards analog based ultrasonic microphones. Most of the PDM versions that measure 60 +KHz are being phased out of production or already obsolete.

Thank you for the reply, i do not think you want my code anywhere near the repo ;). If there is a need in the future maybe I will give it a try

//Kyle