2 layers

Mems mic board
araobp/acoustic-features
Acoustic features (MFSCs and MFCCs) for edge AI
9 parts45GPL-2.0
KiCad boards from 2 GitHub repositories tagged “arm-cortex-m4”, the most starred first; open any of them in PCBKit.

araobp/acoustic-features
Acoustic features (MFSCs and MFCCs) for edge AI

Boardoza/Boardoza_STM32F411_Black_Pill_Development_Board
Compact Black Pill STM32F411-based ARM Cortex-M4 development board offering high performance, USB-C power, and rich peripheral support for advanced embedded applications.

araobp/acoustic-features
Acoustic features (MFSCs and MFCCs) for edge AI