The AXI interface standard, part of the AMBA (Advanced Microcontroller Bus Architecture) family, is a widely adopted, open standard used for high-performance system-on-chip (SoC) designs. It's favored by many IP vendors due to its public, royalty-free nature and status as an industry standard.
According to the provided reference, AMBA AXI4 interface connections are point-to-point and come in three distinct types or "flavors."
The Three Flavors of AXI Interfaces
Based on the standard and common usage, the three main types of AXI interfaces derived from the AXI4 standard are:
- AXI4 (Full AXI): The standard, high-performance version designed for high-bandwidth and low-latency communication. It supports burst transactions and multiple outstanding addresses.
- AXI4-Lite: A simplified version of AXI4, intended for simple, low-throughput memory-mapped interfaces. It supports single transactions and does not support bursts. This is often used for control and status registers.
- AXI4-Stream (AXI-Streaming): Designed for high-speed streaming data transfers between components. It removes the address and response channels present in AXI4 and AXI4-Lite, focusing solely on the data transfer path.
Key Characteristics from the Reference
- Open Interface Standard: AXI is publicly available and royalty-free.
- Widely Used: Adopted by many third-party IP vendors.
- Industry Standard: Recognized and utilized across the industry.
- Point-to-Point Connections: Interface connections link one master to one slave directly.
- Three Flavors: AXI4, AXI4-Lite Slave (the reference specifically mentions 'Slave', but AXI4-Lite is the common term for the interface type used for both master and slave connections in simplified scenarios), and AXI4-Stream.
A Comparison of AXI Interface Types
Here's a quick overview highlighting the differences:
| Feature | AXI4 (Full) | AXI4-Lite | AXI4-Stream |
|---|---|---|---|
| Primary Use | High-performance memory/periphs | Simple register access | High-speed data streaming |
| Transaction | Burst transactions, multiple outstanding | Single transactions only | Data packets (stream) |
| Address Channel | Yes | Yes | No |
| Data Channel | Yes | Yes | Yes |
| Response Channel | Yes | Yes | No |
| Complexity | High | Low | Medium (data focus) |
Note: The reference specifically calls out "AXI4-Lite Slave." While AXI4-Lite can function as both master and slave, its primary application is often in simpler slave interfaces for configuration.
These different types allow designers to choose the most appropriate interface for various tasks within an SoC, optimizing for performance, complexity, and area.
