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Platform Standardizes DSP-Enabled Bluetooth Audio IP for TWS Earbuds

Feb. 24, 2021

Integrated hardware/software IP platform eases combining audio with Bluetooth, providing a drop-in solution for semiconductors and system companies targeting the fast-growing wireless audio market.

David Maliniak

Related To: Microwaves & RF

Unless you have a) an iPhone and b) Apple’s AirPods, there’s a chance you may have found your experience with Bluetooth true wireless stereo (TWS) earbuds lacking. In low-end earbuds, one might find any number of annoyances: poor audio; unstable left/right syncing; short and unequal battery life; and a limited user interface. CEVA hopes to solve these problems with its Bluebud wireless audio platform. Bluebud aims to standardize DSP-enabled Bluetooth audio IP for the fast-growing markets around TWS earbuds, hearables, wireless speakers, gaming headsets, smart watches, and other wearables.

Bluebud is a self-contained, turnkey hardware/software solution that will enable makers of TWS and Bluetooth audio SoCs to get products quickly to market by being ready to just drop into their designs. The platform also allows for differentiation of end products by means of support for host-level application software that can run on the CEVA-BX1 audio processor or an optional host CPU.

The platform combines CEVA’s RivieraWaves Bluetooth 5.2 IP, with both Classic Audio and LE Audio, and the CEVA-BX1 audio processor, together with all the required peripherals for wireless audio, in a compact low-power design with a footprint of less than 0.5 mm² on a 22-nm process. The single-core architecture reduces the overall latency from RF to audio output down to less than 20 ms, ensuring impeccable audio/video sync for movies and gaming. The design also incorporates an advanced power-management unit supporting idle and sleep power-down modes through sophisticated clock and voltage scaling, inherent in the fully integrated Bluetooth audio platform.

Furthermore, the onboard CEVA-BX1 DSP along with the SenslinQ DSP software framework enables semiconductor and OEM users to seamlessly integrate differentiating value-add software from CEVA, its ecosystem partners, or custom software, onto the Bluebud platform. CEVA’s optional software available for Bluebud includes ClearVox multi-microphone noise reduction and acoustic echo cancellation; WhisPro voice trigger and commands; and MotionEngine Hear for user control via tap and double tap, head tracking, in-ear detection, and activity classification. For lite AI inferencing workloads, Bluebud allows users to run TinyML models such as a wake-word engine to summon your voice assistant or detect sound events for contextual awareness, using native support for the TensorFlow Lite Micro neural network framework.

The TWS Challenge

TWS is the key element of wireless earbuds, a situation in which there is one source, but two sinks. The challenge is that TWS is not natively supported by the Bluetooth Classic standard. Bluetooth Classic supports only point-to-point streaming. Phones, tablets, and laptops support only one audio connection at a time, so proprietary techniques are required to support TWS devices.

While there are several techniques for streaming TWS audio using Bluetooth Classic (forwarding, sniffing, and dual stream), the Bluetooth SIG directly addressed the TWS use case in Bluetooth LE Audio, which is natively supported with dual streaming in parallel. The approach CEVA takes in the Bluebud platform is what they’re calling optimized relay, which can be thought of as optimized forwarding. One earbud is connected directly to the audio source using an A2DP stereo link. The second earbud is connected to the first with a Bluetooth LE mono link. As a result, packets are smaller, and the scheme uses less power while providing a stable connection and high audio quality.

Other features of the Bluebud platform include:

Support for Bluetooth 5.2 with both Classic Audio and LE Audio, software upgradeable to next Bluetooth version
Complete Classic Audio software stack, required for Bluetooth audio streaming
A2DP profile for music streaming, including SBC, AAC and MP3 codecs
HFP profile for voice call, including CVSD and mSBC codecs
Complete LE Audio software stack, for audio streaming over Bluetooth low energy
Audio profiles for voice call and music streaming, including LC3 codec
Robust true wireless stereo connectivity for both voice calls and music streaming with low jitter and low latency between left and right channels
Seamless bud-to-bud role switching to maximize battery life
Easy and fast pairing with multi-source support, allowing buds to be connected to several devices and instantly switch between them when required

The Bluebud platform is available for licensing by end of Q1 2021.

CEVA, www.ceva-dsp.com

About the Author

David Maliniak | Executive Editor, Microwaves & RF

I am Executive Editor of Microwaves & RF, an all-digital publication that broadly covers all aspects of wireless communications. More particularly, we're keeping a close eye on technologies in the consumer-oriented 5G, 6G, IoT, M2M, and V2X markets, in which much of the wireless market's growth will occur in this decade and beyond. I work with a great team of editors to provide engineers, developers, and technical managers with interesting and useful articles and videos on a regular basis. Check out our free newsletters to see the latest content.

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About me:

In his long career in the B2B electronics-industry media, David Maliniak has held editorial roles as both generalist and specialist. As Components Editor and, later, as Editor in Chief of EE Product News, David gained breadth of experience in covering the industry at large. In serving as EDA/Test and Measurement Technology Editor at Electronic Design, he developed deep insight into those complex areas of technology. Most recently, David worked in technical marketing communications at Teledyne LeCroy, leaving to rejoin the EOEM B2B publishing world in January 2020. David earned a B.A. in journalism at New York University.