The Automotive Audio Bus (A2B®) provides a multichannel, I2S/TDM link over distances of up to 15 m between nodes. It embeds bidirectional synchronous pulse-code modulation (PCM) data (for example, digital audio), clock, and synchronization signals onto a single unshielded twisted pair (UTP) differential cable. A2B supports a direct point to point connection and allows multiple, daisy-chained nodes at different locations to contribute and/or consume time division multiplexed channel content.
A2B is a single-main, multiple-subordinate node system where the transceiver at the host controller is the main transceiver. The main node generates clock, synchronization, and framing for all subordinate nodes. The main A2B transceiver chip is programmable over a control bus (I2C) for configuration and read back. An extension of this control bus is embedded in the A2B data stream, which grants direct access to registers and status information on subordinate node transceivers, as well as I2C to I2C communication from the host to a peripheral in a subordinate node.
The transceiver can connect directly to general-purpose digital signal processors (DSPs) or microprocessors, field-programmable gate arrays (FPGAs), application-specific integrated circuits (ASICs), microphones, analog-to-digital converters (ADCs), digital-to-analog converters (DACs), and codecs through a multichannel I2S/TDM interface. It also provides a pulse density modulation (PDM) interface for direct connection of up to four PDM digital microphones. The transceiver’s pulse width modulated (PWM) outputs can control LED drivers or voltage regulators. GPIO status and control is directly conveyed between nodes.
Additionally, the transceiver also supports an A2B bus powering feature, where the main node supplies voltage and current to the subordinate nodes over the same daisy-chained, twisted pair wire cable as used for the communication link.
AUTOMOTIVE APPLICATIONS
- Hands free/speech recognition
- Microphone arrays
- In-car telematics and emergency call systems
- Overhead consoles
- In-car communications
