AMBA 3 Overview

AMBA 3 is an older generation of AMBA which introduced the Advanced eXtensible Interface (AMBA AXI) protocol. It also introduced Advanced Trace Buffer (ATB) and extended the APB and AHB protocols.


The AMBA 3 AXI interface specification defines the AXI protocol (which is now referred to as the AXI3 protocol in later generations of AMBA). AXI supports five unidirectional channels with flexible relative timing between them, multiple outstanding transactions and out-of-order data capability. It enables:

  • Pipelined interconnect for high speed operation
  • Efficient bridging between frequencies for power management
  • Simultaneous read and write transactions
  • Efficient support of high initial latency peripherals

AMBA AXI Specification


The AMBA 3 AHB specification introduced the AHB-Lite protocol. It enables interconnect between simpler peripherals in a single frequency subsystem, where the performance of AXI is not required. Its fixed pipelined structure and unidirectional channels enable compatibility with peripherals developed for the AMBA 2 AHB specification.

AMBA AHB Specification


The AMBA 3 ATB specification defines ATB, a data-agnostic interface for transferring trace information between components in a trace system. The trace components and bus sit in parallel with the peripherals and interconnect and provide visibility for debug purposes.

AMBA ATB Specification


The AMBA 3 APB specification extended the APB interface defined in the AMBA 2 specification to include wait states and error reporting functionality. APB supports the low-bandwidth transactions necessary to access configuration registers and data traffic through low-bandwidth peripherals.

AMBA APB Specification

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