A²B Automotive Audio Bus

 

What is A2B?

Automotive Audio Bus (A2B) from Analog Devices, enables the next generation of infotainment systems in the fast-changing automotive industry. A2B helps enables multiple applications such as voice recognition and active noise cancellation.

The Automotive Audio Bus from Analog Devices provides a multichannel, I2S/TDM link over distances of up to 15 meters between nodes. 

 

 

 

 

How does the Automotive Audio Bus (A2B) work?

A2B is a single-master, multiple-slave system where the transceiver chip on the host controller is the master. It generates clock, synchronization and framing SYNCs for all slave nodes. The master A2B chip can be configured via the control bus (I2C). An extension of this control bus is embedded in the A2B data stream and enables direct access to registers and status information of the slave transceiver as well as I2C-to-I2C communication.

 

 

a2b_overview

 

 

 

Less Cables – More efficiency 

The A2B bus delivers high fidelity audio while increasing fuel efficiency, thanks to upward of 75% less cabling weight. A2B connects multiple remote sensors for different applications in a daisy chain sequence, reducing redundant cabling runs. As a result, the weight of the cable harness is reduced, while overall design costs and complexity for the design, installation and maintenance are reduced due to the need for fewer cables. Furthermore the A2B technology can supply power to other devices in the daisy chain, eliminating the need for local power supplies. This is reducing the total system cost further.

 

 

Analog Devices A2B Solutions

 

AD2428

 

AD2428

This master-capable transceiver is used via an I 2 S / TDM interface for checking the clock / synchronization signals for an A 2 B system consisting of up to 10 slave units. This device can also be used as a slave support to belong to slave nodes, which becomes an I 2 S / TDM interface.

 

 

AD2427

 

AD2427

This master-capable transceiver is used via an I 2 S / TDM interface for checking the clock / synchronization signals for an A 2 B system consisting of up to 10 slave units. This device can also be used as a slave support to belong to slave nodes, which becomes an I 2 S / TDM interface.

 

 

 

 

Who is already using A2B?

The largest audio system manufacturers already using A2B technology are Panasonic and Harman / Kardon. Harman / Kardon audio systems are used by BMW, Mercedes-Benz, Volvo, Mini, Jeep, Kia and Subaru.

Numerous established and future markets can benefit from the efficiency of A2B technology. It is used for connections between audio ECUs (head units, amplifiers, intelligent antennas), in microphone arrays for hands-free function, speech recognition and for communication within the vehicle, to suppress ambient noise (ANC) and in active loudspeakers. In many cases, using A2 B technology means lower system complexity, fewer plugs and cables and thus significantly lower system costs compared to analog cabling, especially with multi-microphone arrays. Each AD2428 can support up to four input microphones, saving three of the four microphone lines in an array.

 

 

A2B development tools

a2b_bus_monitor

 

 

The A2B bus monitor from Total Phase is a protocol analyzer that supports you in the development and in the cause of errors in the A2B bus.

By connecting the A2B adapter board between the A2B nodes, the A2B monitor receives A2B data without causing any interference on the line, which enables the user to see the current A2B data traffic on the bus. The A2B superframes are decrypted and broken down into I2S / TDM audio data and I2C control data to simplify debugging. In addition, related interrupts and GPIO handshakes are logged and linked to the data acquisition.