ARM AMBA interconnect protocols suite
AMBA is a collection of bus and interconnect specifications provided by ARM for use in SoCs to attach initiators to targets with different levels of features and protocol complexity. It is an open standard and free to use in SoCs. The specification can be accessed from the ARM website at https://developer.arm.com/architectures/system-architectures/amba/specifications.
The current revision is revision 5. Historically, each newer revision kept backward compatibility with the previous ones but also added new bus protocols with newer features that were developed to keep pace with the modern SoC complexities and higher performance demands. AMBA had to evolve to support multi-core and multi-cluster CPU topologies, which also use some sort of accelerator with all the challenges they present while maintaining the support for lower performance and simpler SoC topologies. The more complex a hardware system becomes. the more power-hungry it will become...