Saved this one to look at a later time.. Glad that someone is making more advanced tutorials, other than a blink or something.. I'm working on a USB audio device application in order to test the I2S output from an audio ADC chip I might want to use in a guitar effects processor. But I'm getting so lost in the complexity of having several libraries for USB (USBX, TinyUSB, USB Device) while none seems to be straightforward to use.. I set up USBX with an audio class device.. But what then? I have one demo application for a microphone expansion board for the NucleoF4, but that's using the old USB library I think.. And on my custom STM32 board I'm using the H503, for which CubeMX doesn't have support for the old library.. So I tried to follow a tutorial on the community forum which explains how to get the old library from github and get it to work for the H503.. But it doesn't compile.. Also, when I try to develop an application for the NucleoF401 with the microphone expansion board, I can set up the USB device and audio device class middleware, but then what? The application compiles, programs without errors and the USB connector on the expansion board enumerates on my laptop with the vendor and device name I gave it, but what functions do I need to call to send audio data? I'm getting lost in the mountain of half complete information online or in documentation, extremely heavy french accent presentations from ST, and what feels like dozens of PDF documents from ST.. The demo application for the microphone board is so bloated with unhelpful comment and whitespace that I barely know where to start looking.. Would you be willing to make a USB audio application example that actually works and which actually explains how to get something to work? By the way, my custom H503 board doesn't have a hardware problem so that's not why it didn't work.. I can program the MCU via USB in boot0 mode with the STM32programmer, so the USB connection works at least.