I would like to use a PDM digital MEMS microphone on my carrier board, but I am not sure how to interface this with the Apalis i.MX6Q. Can I use the I2S channel or digital audio channels or do I need additional processing first?
Thanks for writing to the Toradex Community!
Regarding you question, please have a look here.
The linked question has a lot of good information on the software support using a PDM to I2S converter, but I am more interested in the hardware. Looking online, there are not a lot of PDM to I2S converters and not many direct I2S MEMs microphones. I have found a few white papers that discuss using the output of a PDM MEMs microphone directly on the I2S channels of various microprocessors. I am wondering if you know what would happen to the Apalis iMX6 Quad if that were to happen.
Could the digital decimation occur on the iMX6 in hardware or software?
Would any of the channels be able to support direct PDM input?
Or is the only way to connect a PDM microphone to the Apalis iMX6 through some form of converter that does not seem to be widely sold or supported by most major manufacturers besides Analog Devices?
Currently, the Verdin iMX8M Mini is the only Toradex computer module which has a native PDM microphone input. The i.MX 6 officially does not have a PDM. Unfortunately, that is all I know from the HW side. Maybe one of the software specialists knows more about decoding a PDM stream in software.