Platform and tool chain

Platform

Main board

STMicro STM32L4 (ARM Cortex-M4 with DFSDM, DAC, UART etc) is an all-in-one MCU that satisfies all the requirements of this project:

STMicro NUCLEO-L476RG: STM32L4 development board

My original Arduino shield

I use two MEMS microphones from Knowles:

README and the schematic of the shield

Analog filter for DAC: LPF and AC coupling

Analog filter (LPF and AC couping) is optionally used for monitoring sound with a head phone.

Application processor (host MCU/MPU)

I use Win10 PC as an application processor for developing this system.
I also use RasPi for CNN training and CNN inference for the time being: all the pre-proccessing is performed on STM32L4 and another STM32L4 or F4 will be added to the system for CNN inference in future.

Tool chain

All the tools below are free:

STMicro's CubeMX and TrueSTUDIO(Eclipse/GCC/GDB) for firmware development.
Jupyter_Notebook/python3 with Keras/TensorFlow/numpy/pandas/matplotlib for CNN training and some simulation.
VSCODE/python3 and numpy/pandas/matplotlib/Tkinter for developing Oscilloscope GUI.
STMicro's X-CUBE-AI to generate CNN code for STM32.