combining demo_scripts "self_learning_classifier" and "demo_fft_spectrum" --> crash

Hello everyone,

I have a use case where I need image classification and FFT of the sound recorded by the microphone.

So in a endless loop im doing in fact this:

audio = rx.record(sample_points)
fft_res =,fft_points)
fft_amp = FFT.amplitude(fft_res)
# some thing happening....
# if a certain if statement is fulfilled then
index = classifier.add_class_img(img)

so the first time the classifier (KPU) is doing something then the Maix Bit Mic is crashing.

On the terminal there comes up following statement:

W (3467332668) SYSCALL: sys_exit called by core 0 with 0x1

Of course both of them work when the code runs without the other. (so basically the examples work)
If I comment out the “audio” “fft_res” and “fft_amp” lines, the code also works… it is somehow the combination of FFTs and classifier…

Any suggestions?