no audio data from PC send to STM32F4 audio class USB

Question

I'm working in an audio project. We use stm32f407 like a USB audio device to get audio data from PC then send out by I2S module. We are using stm32f4 Discovery kit and STM32cubeMX. After generate code by following this video , i change nothing and flash to Kit; my PC identifies that STM Audio device but there isn't any data send to my kit when play music, except MuteCMD . My question is:

• i don't know which function is callback when data stream from PC to Kit.

• why PC identifies that my kit is an audio output device but the callback of volume control isn't called when I config volume on PC and there isn't any data of music send to my device. The only one mute control callback function is called when i mute the PC.

this is my config in STM32cubeMX

pinout config figure

USB device config figure 1

USB device config figure 2

USB device config figure 3

PC identifies AUDIO device figure

choosing PC's audio output device figure

fail to play test tone figure

Answer 1

You should set USBD_AUDIO_FREQ to 22050 (or 44100, or 11025). Your value is 22100 and it seems like Windows or built-in audio drivers can't use that frequency.

Answer 2

I had exact same problem.
My project is generated from STM32Cube.
Windows recognizes the F7-DISCO board as sound card but failed to play test sounds.

I changed USBD_AUDIO_FREQ to 48000 and PID to 0x5730 (22320 in decimal).
And then everything works fine.