As an ADI Alliance design partner, Cardinal Peak has a wealth of experience with Analog Devices components, particularly with A2B parts, Sharc processors and Software Defined Radios (SDR) components. We have been particularly excited to see A2B gain traction over the years. Analog Device’s A2B (Automotive Audio Bus) moved from the car to the broad market in 2019 when ADI started incorporating A2B into a variety of their broad-market parts such as the SHARC microprocessors. With these new parts, we have seen A2B start being adopted in other markets as it addresses a variety of common audio product design engineering challenges. Cardinal Peak first gained experience with A2B with our automotive customers and has since incorporated it into designs in other markets as outlined later in this brief.
Fundamentally, A2B is a daisy-chained, single twisted pair, bi-directional data bus that is ideal for supporting multiple channel audio with no jitter and extremely low, fixed latency (50 µs). By ensuring simultaneous sampling and delivery of data on all system nodes for each frame, A2B technology delivers deterministic and very low, sub-50 microsecond (µs) latency. Ideal for transporting digital audio, A2B features a configurable 44.1 kHz or 48 kHz frame rate and up to a 50 Mbps bandwidth to deliver truly superior audio quality relative to analog connections.
The reason this solution is compelling in automotive applications is because of the proliferation of distributed infotainment, voice, and noise cancellation in modern cars. Keep in mind that for voice and noise cancellation that low latency or minimal delay is very important. The figure below contrasts the old solution to an A2B implementation. For those not working on automotive products every day, the figure highlights the plethora of connections in a modern car. Everyone is familiar with the head unit and the distributed speakers/sub-woofer, but in addition, you also find a series of microphones distributed throughout the car that are used for road noise reduction in the cabin as well as tuning the audio, along with microphone arrays in both the front and back seats for voice control and hands-free calling. The left side of the figure is the traditional approach and the right side is the A2B solution. Note the simplification in the wiring harness at the bottom of the figure.
In practice, A2B has several other advantages beyond those described above (which included simplified wiring, no jitter, low latency). While A2B doesn’t need to be used just for audio, we do see that distributed audio (speakers, microphone arrays, etc.) is a growing need in a variety of markets thanks to the advances in voice control (beam forming, echo cancellation, etc.). Working in both the voice control space as well as the Pro Audio market, we have a deep appreciation for maintaining audio quality with extremely low latency.
We see another other key design aspect of A2B as the ability to communicate audio and other data simultaneously with GPIO. This means end devices do not require separate processors. While processors might not be expensive these days, having multiple processors in a system adds complexity with both inter-processor communication as well as keeping firmware revisions on the different processors in sync. Driving GPIO on secondary end-devices from a primary device is a great simplification that lowers NRE, BOM, long term maintenance, and likely reduces future user complaints. The figure below illustrates this feature.
As mentioned earlier, Cardinal Peak has done a series of projects which utilize A2B.
For a gaming customer, we developed a high-speed, low latency, 12 channel bi-directional audio network using A2B. This project included both hardware and software development.
For an original equipment automotive amplifier manufacturer, we helped with a series of projects.
Other markets where we see an advantage for A2B include:
For more information on how A2B works, its advantages and applications both in the automotive industry and beyond, check out our blog series “Taking Analog Devices’ A2B Audio Bus Beyond Automotive Applications.”
As an Analog Devices design partner for A2B, if you have an application in any of the areas above (or others) that you would like to discuss, please contact us.