Really nice project! Great care is taken in optimized audio feature extraction, very cool to see. I am working on a very similar project[1], using the Puya PY32

Really nice project! Great care is taken in optimized audio feature extraction, very cool to see. I am working on a very similar project[1], using the Puya PY32. I opted for that chip over CH32 since it has DMA (simplifies efficient ADC input at audio rates), and 1 kB more RAM. For a couple of cents more. I have written about some of the hardware constraints on low cost audio already, and am getting to the audio DSP/ML in the next months. 1. https://hackaday.io/project/194511-1-dollar-tinyml https://hackaday.io/project/194511-1-dollar-tinyml