AMBA

AMBA, short for Advanced Microcontroller Bus Architecture, is a family of on‑chip interconnect standards developed by ARM Holdings. It defines a set of protocols and interface specifications that connect processors, memory controllers, and peripherals within a system‑on‑chip, enabling modular design, IP reuse, and interoperability across different silicon implementations.

The AMBA family covers several bus protocols with different performance goals. The Advanced High-performance Bus (AHB) provides a pipelined, high‑throughput backbone for core-to-memory and core‑to‑peripheral communication. The Advanced Peripheral Bus (APB) offers a simple, low‑power interface for peripherals and config registers. The Advanced eXtensible Interface (AXI), introduced in AMBA 4, is a high‑performance, scalable protocol featuring separate read and write channels, multiple outstanding transactions, burst transfers, and wide data paths.

AMBA has evolved through multiple generations. AMBA 2 and AMBA 3 established widely used bus concepts and bridges between AXI, AHB, and APB. AMBA 4 added AXI as the dominant high‑performance interface and expanded its scalability. AMBA 5 introduced coherent interconnect technology, including the CHI (Coherent Hub Interface) and ACE (AXI Coherency Extensions), to support cache‑coherent communication among multiple processors and accelerators in heterogeneous, multi‑core systems.

In practice, AMBA standards are widely adopted in ARM‑based SoCs across mobile, embedded, and consumer electronics. They provide a common framework for integrating diverse IP blocks, reducing custom bus development, and enabling smoother IP reuse and ecosystem interoperability. Vendors may implement AMBA components and bridges with their own optimizations, while remaining compatible with the standard interfaces.