Arm AMBA 4 Specification Maximizes Performance And Power Efficiency

The AMBA specification is the de facto standard for system on-chip interconnects, and was introduced by ARM more than 15 years ago. Like its predecessor AMBA 3, introduced in 2003, the AMBA 4 specification has been designed by and for the industry with contributions from thirty-five of the industry’s leading OEM, semiconductor and EDA vendors.

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, and is a natural extension of the AMBA 3 specification. 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 new AMBA 4 specification and the AXI4 protocols have also been extended to meet the needs of 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 an efficient streaming interface for non address-based, point-to-point communication, such as video and audio data.

“These new specifications are a clear demonstration of the ongoing technical development and innovation in on-chip communication by ARM, and also the ongoing extension of the AMBA specification into new areas such as the FPGA community,” said Keith Clarke, VP & GM of Fabric IP -Processor Division, ARM. “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. The AMBA 4 specification will take embedded system design to performance and efficiency levels considered the exclusive domain of desktop, laptop and network equipment.”

Early adopters of these new specifications include Arteris, Cadence, Mentor, Sonics, Synopsys and Xilinx.

“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, sr. VP Worldwide Marketing and Business Development, Xilinx. “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 new AMBA 4 specification will be issued later in 2010. 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, further maximizing performance and power efficiency.

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