As of 15 March we reached both of our stretch goals! You can order an Audio Expander Capelet which converts Bela's analogue ins and outs into extra audio channels, or a Multiplexer Capelet which gives you 64 analogue inputs. See "Rewards" below for details on ordering.
What is Bela?
Bela is an embedded computing platform developed for high quality, ultra-low latency interactive audio. Bela provides stereo audio, analogue and digital I/O in a single self-contained package. It combines the processing power of the BeagleBone Black embedded computer with the timing precision and connectivity of a microcontroller.
Bela features an on-board, browser-based IDE, making it easy to get up and running without requiring any additional software. The end result: digital instruments and interactive objects that are faster to develop and more responsive to use.
A dedicated hardware and software environment provides hard real-time performance with 1ms latency while retaining the capabilities and power of a 1GHz embedded computer running Linux.
Use Bela's stereo audio input and output to create musical instruments and audio effects. Connect to the physical world with Bela's 8 analogue inputs, 8 analogue outputs and 16 digital I/O pins. You can also use ethernet, USB (including MIDI), SD card storage and other features of the BeagleBone Black.
Bela's compact form factor means that it easily integrates into portable interactive objects. It's a self-contained processing platform that eliminates the need for a laptop. It's also easily battery powered so completely mobile.
Get started in minutes - plug in Bela, launch the on-board IDE, and start coding and compiling in C++. Alternatively you can run patches developed for Bela using the graphical computer music language Pure Data, and compiled with the Heavy audio tools.
Who is Bela for?
Bela is for anyone who wishes to develop powerful and responsive embedded interactive audio applications. It is particularly suited to electronic musicians and instrument designers, but is also useful for artists, makers and other embedded hardware programmers who want to take advantage of its ultra-low latency audio and sensor processing capabilities.
Bela is designed with audio in mind. It uses the BeagleBone Black single-board computer which features a 1GHz ARM Cortex-A8 processor and 512MB of RAM. It runs a custom Linux audio environment that gives you buffer sizes as small as 2 samples, producing latency as low as 1 millisecond from audio in to audio out, or even down to 100 microseconds from analogue in to analogue out. What's more, every analog and digital pin is automatically sampled at audio rate, providing precise, jitter-free alignment between audio and sensors.
What this means for you is that your digital musical instruments and interactive hardware just got a lot more responsive and expressive: Bela's speed and timing precision allow for natural, intuitive and immediate gestural control. Digital instrument design has never been this elegant.
Connect Bela to your laptop via USB, bring up the dedicated on-board IDE in your browser and you can start coding right away in C++. Custom developer toolchains are also supported through a set of build scripts. Bela supports a lightweight and simple Arduino-like API that allows you to focus on the core functionality of your code. The IDE also includes a browser-based oscilloscope to visualise and debug your sensor and audio data in real time.
Alternatively, build patches for Bela in the powerful computer music programming environment Pure Data. We use Heavy Audio Tools from Enzien Audio to convert your Pd patch into optimised C code which is compiled to run natively on Bela.
When you are done developing you can unplug Bela from your laptop, power it with a battery, and embed it in your project, be it a musical instrument, interactive installation or kinetic sculpture. No laptop required.
- Audio: 16-bit stereo audio I/O at 44.1kHz
- Audio power output: 2x 1W 8ohm speaker amplifiers (available when powered from DC jack)
- Analogue In: 8x 16-bit analogue inputs at 22.05kHz
- Analogue Out: 8x 16-bit analogue outputs at 22.05kHz
- Digital channels: 16x digital GPIO at 44.1kHz or 88.2kHz
- Analogue I/O is also software configurable to give 4 channels at 44.1kHz or 2 channels at 88.1kHz
Bela runs a custom audio processing environment based on the Xenomai real-time Linux extensions. Your audio code runs in hard real-time, bypassing the entire operating system to go straight to the hardware. We have written a custom audio driver using the Programmable Realtime Unit (PRU), a microcontroller on the same chip as the BeagleBone Black CPU. This driver is capable of buffer sizes as small as 2 audio samples for very low latency, and its performance is not affected by other system load. No other embedded Linux platform can match this performance.
The Bela C++ API gives you a clean and lightweight way to write audio code. Fill in three functions: setup() runs at the beginning; render() runs once for each new audio buffer; cleanup() runs once at the end. All the analogue and digital pins are sampled automatically at audio rate, so sensor signals can be treated the same way as audio in your code. You can write your code using the browser-based IDE, or alternatively a set of build scripts let you use an editor of your choice and then compile the code on the board.
Comparison to other tools
Bela combines the low-latency real-time performance of microcontrollers with the power and connectivity of embedded Linux computers. Through Bela's dedicated design we can achieve audio latency lower than even a high-end laptop.
We'll be adding examples of projects made with Bela throughout the campaign.
Giulio demonstrates using libpd on Bela with an analogue synth:
Liam, Astrid and Dan made Axis, a kinetic sculpture that uses Bela to control 20 stepper motors over I2C:
Liam demonstrates Bela's IDE, with in-browser oscilloscope:
Robbie and Chris from the Augmented Instruments Lab turned poster tubes into light sabers using Bela and Pd, and explain how they did it:
Tank Wars, a game made with Bela and played on an oscilloscope:
The D-Box, a hackable musical instrument:
After the campaign we're still going to be posting videos, so click here and subscribe to our YouTube channel.
- Bela cape: provides stereo audio and analogue in/out for your own BeagleBone Black. Includes 2 audio adapter cables.
- Bela starter kit: includes a BeagleBone Black, Bela cape and an SD card pre-flashed with the Bela image
- Bela experimenter's kit: explore the capabilities of Bela with a BeagleBone Black, cape, SD card and a varied selection of sensors (see full list in FAQ).
- D-Box: the D-Box is a hackable musical instrument based on Bela. It can be rewired by the performer using circuit bending techniques. A limited number of D-Box kits are available.
- Workshop kit: 10 Bela starter kits plus spare cables and SD cards. Great for universities and makerspaces.
Update: on 15 March we reached both our stretch goals! That means you can order an Audio Expander Capelet and/or a Multiplexer Capelet. The Audio Expander Capelet turns the analogue inputs and outputs into extra audio channels. The Multiplexer capelet gives you 64 analogue inputs. Each capelet costs £35. To order, add £35 to your pledge (or £70 for both). You don't need to select a different reward.
The Audio Expander capelet uses the same type of audio adapter cable as the two which come with the Bela cape. If you want extra audio adapter cables, these can be ordered for £2 each.
Why we need your support
Bela is open-source hardware and software. It has been developed within the Augmented Instruments Laboratory in the Centre for Digital Music at Queen Mary University of London. We know how useful Bela is and now we want to open this platform up to you! We want you to experiment, invent, build, and play with Bela, and help us to shape the future of this platform. Join our growing community of musicians, engineers and makers enjoying the power of low-latency physical computing.
This project is also supported by the QMUL Centre for Public Engagement and the UK Engineering and Physical Sciences Research Council.
Risks and challenges
Bela is already developed and ready to go. We have been developing and using it in the Centre for Digital Music at Queen Mary University of London for the past 2 years, and we continue to improve the API and add features.
Any hardware project comes with practical risks. For example, the manufacturer of our capes might encounter delays which would affect our ship date, especially in the case of a large production quantity. We have limited the number of rewards with an early ship date to help ensure we meet our shipping estimates. There is also a risk that the BeagleBone Black could go temporarily out of stock, delaying the delivery of starter kits.
That said, we have run a Kickstarter campaign before, and we are confident that we can deliver you high-quality boards in a timely manner.Learn about accountability on Kickstarter
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