Quick start¶

Warning

XMOS development boards are typically supplied with no firmware pre-programmed.

The following steps explain how to program the USB Audio software onto a development board and use it as a USB Audio device. Each step is explained in detail in the following sections.

Download the latest USB Audio 2.0 Device software release from the XMOS USB & Multichannel Audio webpage, using the DOWNLOAD SOFTWARE link.
- Before downloading the software, review the licence and click Accept to initiate the download.
(Section USB Audio reference software.)
If using a Windows host computer, download the USB Audio Class 2.0 Evaluation Driver for Windows.
- On the XMOS USB & Multichannel Audio developer webpage, follow the DRIVER SUPPORT link, and click on DOWNLOAD EVALUATION DRIVER. Once downloaded, run the executable and install the driver.
(Section USB Audio Class (UAC) 2.0 evaluation driver for Windows.)
Download and install the XMOS XTC Tools
- The required XTC Tools version for compiling USB Audio applications can be found in the README file supplied in the software package. Be sure to download the correct version of the tools.
(Section XMOS XTC development tools)
Compile the software relevant to the available board.

(Section: Building the firmware)
Connect the board to the host machine using two connections: one for the USB Audio device and another for the debug/programming interface, and program the compiled binary onto the board.

(Section Running the firmware)
Connect audio input and output devices, and play audio.

(Section Playing/recording audio)

USB Audio reference software¶

The USB Audio Reference Design software is available free of charge from XMOS.

When downloading the software for the first time, the user needs to register at http://www.xmos.com/.

To download the software:

On the XMOS USB & Multichannel Audio webpage, follow the DOWNLOAD SOFTWARE link
Review the licence agreement and click Accept.
Download and save the software when prompted.

The software is distributed as a zip archive containing pre-compiled binaries and source code that can be built using the XMOS XTC Tools.

USB Audio Class (UAC) 2.0 evaluation driver for Windows¶

Note

Since version 10.6.4, macOS natively supports USB Audio Class 2.0 – no driver install is required.

Note

Since version 10, release 1703, Windows natively supports USB Audio Class 2.0 – no driver install is required.

Earlier Window versions only provides support for USB Audio Class (UAC) 1.0. To use a UAC 2.0 device under these Windows versions requires a third party driver.

Developers may also wish to use a third party driver for reasons including:

ASIO support
Advanced clocking options and controls - such as synchronisation to an external S/PDIF or ADAT clock
Improved latency
Native DSD (via ASIO)
Branding customisation and custom control panels
Large channel count devices
Etc

XMOS therefore provides a free Windows USB Audio driver for evaluation and prototyping and a path to a more feature-rich multichannel production driver from partner Thesycon.

The evaluation driver is available via the USB Audio Driver Support webpage.

XMOS XTC development tools¶

The XMOS XTC tools provide everything required to develop applications for xcore multicore microcontrollers and can be downloaded, free of charge, from XMOS XTC tools. Installation instructions can be found here. Be sure to pay attention to the section Installation of required third-party tools.

The XMOS XTC tools make it easy to define real-time tasks as a parallel system. They come with standards compliant C and C++ compilers, language libraries, simulator, symbolic debugger, and runtime instrumentation and trace libraries. Multicore support offers features for task based parallelism and communication, accurate timing and I/O, and safe memory management. All components work off the real-time multicore functionality, giving a fully integrated approach.

The XTC tools are required by anyone developing or deploying applications on an xcore device. The tools include:

“Tile-level” toolchain (Compiler, assembler, etc)
System libraries
“Network-level” tools (Multi-tile mapper etc)
XSIM simulator
XGDB debugger
Deployment tools

The tools as delivered are to be used within a command line environment, though may also be integrated with VS Code graphical code editor.

Building the firmware¶

Note

For convenience the release zips provided from XMOS contain precompiled binary (xe) files.

Applications are compiled using XCommon CMake which is a CMake based build system.

Note

See Build system for more details.

Each board is supported by a dedicated application located in its own directory. The boards and their corresponding applications are listed in Table 1.

Table 1 Boards and their applications¶
Board	Application
XK-EVK-XU316	app_usb_aud_xk_evk_xu316
XK-AUDIO-216-MC	app_usb_aud_xk_audio_216_mc
XK-AUDIO-316-MC	app_usb_aud_xk_audio_316_mc

The primary configuration for applications is in CMakeLists.txt. It is present in each application directory (e.g. app_usb_aud_xk_audio_316_mc). This file specifies build configs, sources, build options and dependencies.

From a command prompt with the XMOS tools available, follow these steps:

Unzip the package zip to a known location
From the relevant application directory (e.g. app_usb_aud_xk_audio_316_mc), execute the commands:
```
cmake -G "Unix Makefiles" -B build
xmake -j -C build
```

These steps will configure and build all of the available and supported build configurations for the application.

Running the firmware¶

To support different feature sets and products, multiple build configurations are provided. Each configuration produces a distinct binary. Table 2 lists the recommended build configurations for initial evaluation.

Table 2 Applications and suggested build configuration for quick start¶
Application	Suggested build config	Description
app_usb_aud_xk_evk_xu316	2AMi10o10xssxxx	UAC 2.0, 10 ch in/out, 8 analogue channels in/out, S/PDIF in/out
app_usb_aud_xk_audio_216_mc	2AMi10o10xssxxx	UAC 2.0, 10 ch in/out, 8 analogue channels in/out, S/PDIF in/out
app_usb_aud_xk_audio_316_mc	2AMi2o2xxxxxx	UAC 2.0, 2 ch in/out, 2 analogue channels in/out

During development, it is common to load the application binary directly into the device’s internal RAM via JTAG and execute it immediately.

Boards require two USB connections, one for the USB Audio device and another for a debug interface. Depending on the board being used, the debug interface will either use an integrated or xTAG.

To run one of the compiled binaries, follow these steps:

Connect the USB Audio board to the host computer with a USB cable (typically labelled USB or USB DEVICE)
Connect the xTAG to the USB Audio board, and then connect the xTAG to the host computer using a separate USB cable. Note: Some boards have an integrated xTAG.
Ensure that any required external power supplies are connected.

Once everything is connected, run the binary on the target device using a command like the following:

xrun ./bin/2AMi10o10xssxxx/app_usb_aud_xk_316_mc_2AMi10o10xssxxx.xe

The device should now appear as a USB Audio Device on the host computer. It will continue to function as such until the board is power cycled.

Writing the application binary to flash¶

If desired, the application binary can be programmed into the device’s boot flash. To do so:

Connect the USB Audio board to the host computer with a USB cable (typically labelled USB or USB DEVICE)
Connect the xTAG to the USB Audio board, then connect the xTAG to the host computer using a separate USB cable. Note: Some boards include an integrated xTAG.
Ensure any required external power supplies are connected.

Once everything is connected, flash the binary on the target device using a command like the following:

xflash ./bin/2AMi10o10xssxxx/app_usb_aud_xk_316_mc_2AMi10o10xssxxx.xe

After flashing, the device will automatically reboot and begin executing the application. Subsequent power cycles will cause the device to boot and run the flashed binary.

Playing/recording audio¶

To play and record audio using the USB Audio board, follow these steps:

Connect the board to a power supply, if required. Note: Some boards are powered via USB and do not require an external supply.
Connect the board to a host system using a USB cable. Ensure the host supports USB Audio Class.
Install the Windows USB Audio 2.0 demonstration driver, if required.
Connect audio input/output devices to the appropriate connectors on the board (e.g., powered speakers, MP3 player). For multichannel boards use input/output 1/2.
In your audio application, select the XMOS USB Audio device.
Begin audio playback and/or recording.