“Black /Green pill stm32f401 , high quality, low noise DAC based on 2 PWM timer channels with virtual software Sigma Delta ADC.
DIY about $3-$9 (depends number of displays) low cost solution Software low noise DAC based on 2 PWM timer channels with virtual soft Sigma Delta ADC between stream from usb and PWM output. There is implemented “sigma-delta floating point encoder” workaround of native stm32f401 limit 10.5 bits on 44100 Hz (1904 levels=84MHz/44.1KHz ) So, we can have for only $3 ,very low noise , high sound quality solution, which better then most onboard sound cards !
There is implemented virtual software second order sigma delta adc for the shift quantization noise to high frequency. see here (it provide useful links at the end):
https://www.analog.com/media/en/training-seminars/tutorials/MT-022.pdf
But instead one bit ( two levels ) i use more bits (0-MAX_LEVELS) Same technology can be used for esp32 high quality sound rendering.
stm32f401cdu6 version https://github.com/sdima1357/stm32f401cdu6_Audio
stm32f401ccu6 version https://github.com/sdima1357/stm32f401ccAudioNative”