So, as per request, here's the UART controlled VSOS audio player example. I haven't tested it for a while but it used to work so I assume it still does, at least to some degree.
The attached VSIDE project DevUart builds a VSOS library which simply provides UART communication through a FILE interface.
UartMp3 is a VSIDE project for a VSOS app which loads the mp3 model and a playlist, associates them with each other and starts waiting for commands via UART. The commands are basically UIMSG messages that are represented in an ASCII format. When a message is received, it is decoded and sent to the mp3 model. Likewise, when the model sends us a message, it is encoded to ASCII and forwarded to the UART file. (You can get an idea of the ASCII message format by looking at the first function at "vc.c".)
Finally, UartMp3PC is a Visual Studio project which builds a small Windows executable which lets you test basic music playback functionality. Of course, the operation relies upon a working UART connection between the PC and the VS1005 developer board.
Discussion about writing software for VS1005 and the VSOS Operating System. Also posts about VS1005-related hardware design and device drivers should be posted here.