USB Audio Visualizer

An audio visualizer as an USB sound card.
Thanks to DiscoveryF7Audio, I don't have to crack the USB audio and on board DAC playback on my own.

Features

Demonstration Video

• Recongized as an USB audio sound card(via USB_FS connector on the board)
• Audio Playback(via 3.5mm OUT on the board)
• Output volume adjustment
  • Via slide bar at the bottom of the GUI
  • Scale of left and right VU-meters changes with the slider
  • Scale of the wave graph doesn't change with the slider
• Wave graph
  • Color adjustment
  • If left and right audio are different, the graph will be partially columnized

    Sin wave(550 Hz)	Sin wave(550 Hz)
    Left-right channel balanced	Right channel louder

Development Enviroment

It's possible to have this project build in GNU enviroment, not replying on STM32CubeIDE, just using makefile. When generating code from STM32CubeMX, you can select project as Keil, Eclipse, gcc..., etc.

• IDE: STM32CubeIDE 1.4.0
• Toolchain: arm-none-eabi, GNU Arm Embedded Toolchain 9-2020-q2-update 9.3.1
• Code Generator: STM32CubeMX 6.0.1
• GUI Framework: TouchGFX 4.15.0
• OS: Windows 10

TODO

• Fix #9 Audio corrupts(electronic noise) sometimes
• Feat: Plot in frequency domain with histogram by using fast fourier transformation.
• Feat: Change the frequency domain and output it in realtime, like an equalizer.

File Structures

• Folder Tree

  equalizer/
  ├── Core            // Top layer, main entry
  │   ├── Inc         // top layer header files
  │   └── Src         // main.c and interrupt subroutines here
  │
  ├── Drivers         // Mostly auto-generated, do not modify
  │   ├── BSP         // board support package
  │   ├── CMSIS
  │   └── STM32F7xx_HAL_Driver
  │
  ├── Middlewares     // Touchgfx and USB libraries
  │
  ├── TouchGFX        // GUI
  │   ├── assets      // fonts, images, texts
  │   ├── build       // object files compiled by touchGFX
  │   ├── generated   // auto-generated, do not modify
  │   ├── gui         // User features implementation. It is auto-generated only once.
  │   ├── equalizer.touchgfx  // touchGFX project file, json format
  │   └── simulator   // Visual Studio simulator project, not used
  │
  ├── .project        // stm32cubeIDE project file
  └── equalizer.ioc   // CubeMX project file

• Important files

  Description	Path
  STM32CubeIDE project	./.project
  GUI project (touchGFX)	./TouchGFX/equalizer.touchgfx
  GUI Features	./TouchGFX/gui/src/screen_screen/screenView.cpp
  USB audio to on board DAC	./USB_DEVICE/App/usbd_audio_if.c
  Binrary (not included in source control)	./STM32CubeIDE/Debug/equalizer.bin