A²B Automotive Audio Bus
What is A2B?
The Automotive Audio Bus (A2B) is a bus developed by Analog Devices for infotainment systems in the automotive industry. A2B enables multiple applications such as speech recognition and active noise cancellation. Analog Devices' Automotive Audio Bus provides a multi-channel I2S / TDM connection over distances of up to 15 meters between nodes.
How does the Automotive Audio Bus work?
A2B is a single-master, multiple-slave system in which 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 allows direct access of registers and status information of the slave transceiver as well as I2C-to-I2C communication.
Less cable - more efficiency
The A2B bus provides HI-FI audio while increasing fuel efficiency thanks to a 75% reduction in cabling weight. A2B connects multiple remote sensors for different applications in a daisy-chain sequence, significantly reducing redundant cabling runs. As a result, harness weight is dramatically reduced while overall design cost and complexity are reduced due to the need for fewer cables. A2B technology can also power other devices in the series connection, eliminating the need for local power supplies and further reducing overall system costs.
AD2428
This master-capable transceiver has an I 2 S / TDM interface to provide the clock / synchronization signals for an A2B system consisting of up to 10 slave devices. This device can also be configured as a slave to support slave nodes that require an I 2 S / TDM interface.
AD2427
With A and B side LVDS transceivers, this midline microphone slave node device (no I 2 S / TDM interface) supports up to 32 bus slots in each direction.Which manufacturers are 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 in audio ECU (head unit, amplifier, smart antennas) interconnects, in microphone arrays for hands-free, speech recognition and in-vehicle communication, for ambient noise cancellation (ANC), and in active loudspeakers. In many cases, using A2 B technology means less system complexity, fewer connectors and cables, and thus significantly lower system costs compared to analog cabling, especially in 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
Total Phase's A2B Bus Monitor is a protocol analyzer that helps you develop as well as troubleshoot the A2B bus.
By connecting the A2B adapter board between the A2B nodes, the A2B Monitor receives A2B data without causing interference on the line, giving the user insight into the current A2B traffic of the bus. The A2B superframes are decoded and decomposed into I2S/ TDM audio data and I2C control data to facilitate debugging. In addition, related interrupts and GPIO handshakes are logged and associated with the data acquisition.