Developed by CTAG Audio in collaboration with Bela, the FACE is a cape for the BeagleBone Black with 4 audio input channels and 8 audio output channels. The BEAST, created by stacking two FACE capes on top of each other, doubles the amount of available audio I/O to an impressive 8 input channels and 16 output channels.
A FACE cape installed on a BeagleBone Black.
The full stack: a BeagleBone Black, the BEAST and a Bela cape.
The CTAG face2|4 (4in/8out) and CTAG Beast (8in/16out) are open-source multi-channel audio cards for the BeagleBone (AM335x SoC) single board computer, forming an embedded audio system for low-latency multi-channel applications.
The system is based on the AD1938 24-Bit Codec featuring 4 ADC/8 DAC with PLL, 192 kHz.
|audio inputs/outputs (FACE)||4/8|
|audio inputs/outputs (BEAST)||8/16|
|sample-rate/bit-depth (ALSA)||48, 96, 192KHz/24bit|
* Guaranteed by Bela’s hard-real-time environment
** Dependent on system load
Originally, the CTAG audio cards drivers were developed for the Advanced Linux Sound Architecture (ALSA), making the audio cards compatible with traditional Linux applications and common sound servers (e.g. JACK).
All drivers required to essentially spawn an 8-channel ALSA PCM device are apparently in the mainline GitHub - beagleboard/linux: The official BeagleBoard and BeagleBone kernel repository already.
Added support for CTAG face2|4 Audio Card · beagleboard/linux@590bbb6 · GitHub
- The ASoC machine driver for CTAG face2|4 Audio Card
- Base device tree for BeagleBone Green with CTAG face2|4 Audio Card
Added device tree for BB-X15 and CTAG face2|4 · beagleboard/linux@f8e88ac · GitHub
- Device tree for BeagleBoard-X15 with CTAG face2|4 Audio Card
Henrik Langer adapted the CTAG audio card drivers to Bela: The platform for ultra-low latency audio and sensor processing, resulting in a novel, embedded audio platform for ultra-low-latency, multi-channel applications (e.g. Ambisonics). The complete project is open-source, thus all driver components can be used for experimenting.
The ultra-low-latency of Bela was achieved by using a real-time framework for Linux (Xenomai) and the Programmable Realtime Unit Subsystem (PRUSS) of the AM335x SoC. Hence, Bela is using a self-developed unique, real-time driver architecture.
For more information and development history, see CTAG face2|4: A Linux-Based Low-Latency Multichannel Audio System, the Hackaday project page and the corresponding CTAG wiki page.
Oct 29, 2018 (GA)
CTAG multi-channel audio capes