The original AMBA specification was introduced by ARM more than 15 years ago. AMBA-3 was introduced in 2003. The AMBA-4 specification has been written with contributions from 35 companies that include OEMs and semiconductor and EDA vendors, ARM said. Early adopters of the specifications include Arteris, Cadence, Mentor, Sonics, Synopsys and Xilinx.

Phase one of the AMBA-4 specification includes definition of an expanded family of AXI interconnect protocols including AXI4, AXI4-Lite and AXI4-Stream. The AXI4 protocol adds support for longer bursts and quality-of-service (QoS) signaling. Long burst support aids integration of devices with large block transfers, while QoS signaling provides the ability to manage latency and bandwidth in complex multi-master systems.

The AMBA-4 specification and the AXI4 protocols have also been extended to support FPGA implementations. AXI4-Lite is a subset of the full AXI4 specification for simple control register interfaces, reducing SoC wiring congestion and simplifying implementation, while the AXI4-Stream protocol provides a streaming interface for non-address-based, point-to-point communication, such as video and audio data.

"Standards such as AMBA, which are widely adopted across the industry, enable significant benefits in design reuse, increased efficiency and interoperability which can be utilized by every level of the design community," said Keith Clarke, vice president and general manager of the fabric IP processor division of ARM, in a statement.

"We have worked closely with ARM on the definition, development and review of the AMBA-4 AXI4-Lite and AXI4-Stream specifications," said Vin Ratford, senior vice president responsible for marketing and business development at Xilinx, in the same statement. "As the line between chips and systems continues to blur, we need to adopt open standards such as AMBA to enable developers to combine the high-speed parallel processing performance possible in FPGAs with traditional processor based systems."

Announcements regarding phase two of the AMBA-4 specification will be issued later in 2010, ARM said. These will include additional enhancements such as memory coherency and barriers support, which will simplify the software programmer's view of the compute sub-system and reduce traffic to the external memory.

The AMBA-4 phase-one specifications including AXI4, AXI4-Lite and AXI4-Stream can be downloaded from www.amba.com.

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