Figure 2-1: AXI Interconnect Core Diagram
Use Models
AXI互联模块将一个或多个内存映射的主设备连接到一个或多个内存映射的从设备，主设备可以是发起AXI事务的IP核，也可以是级联的AXI互联模块的主接口（MI）。从设备可以是AXI事务的接收者（IP核或者级联的AXI互联模块）。 AXI互联模块也可以连接一个主设备到一个从设备时。软件工具会自动例化并配置。基本连接模式： ? N-to-1 Interconnect ? 1-to-N Interconnect ? N-to-M Interconnect (Crossbar Mode) ? N-to-M Interconnect (Shared Access Mode)
N-to-1 Interconnect
当多个主设备仲裁访问一个从设备时，例如访问内存控制器，使用N-to-1配置。在配置中可以实现任意可选的转换功能。
Figure 2-2: N-to-1 AXI Interconnect
1-to-N Interconnect
slave0Interconnectmasterslave1
N-to-M Interconnect (Crossbar Mode)
The N-to-M use case of the AXI Interconnect core, when in Crossbar mode, features a Shared-Address Multiple-Data (SAMD) topology, consisting of sparse data crossbar connectivity, with single, shared Write and Read address arbitration,
Figure 2-3: Shared Write and Read Address Arbitration
Sparse Crossbar Write and Read Data Pathways
并行读写数据路径根据配置的连接映射将SI slot连接到可以访问的所有MI slot。当多个源需要将数据发送到不同目的地时，数据传输时彼此独立、同时发生的。而地址是需要仲裁的。
N-to-M Interconnect (Shared Access Mode)
对于主设备来说，读事务请求总优先于写任务。Shared Access mode（共享访问模式）：即地址和读写数据都是共享总线的。
Figure 2-4: Shared Access Mode
性能
AXI Crossbar Performance: SAMD, AXI4 Protocol
Common Configuration:
? Connectivity Mode: SAMD (Maximize Performance strategy) ? Protocol: AXI4 or AXI3
? Data Width: 64 or 256 (as noted) for Kintex-7, Virtex-7, Zynq-7000, and Kintex UltraScale; 64 for Artix-7
? Read/Write Connectivity: all MI fully connected for read and write ? Thread ID Width: 0 (all SI)
? Address Width: Global = 32; per MI = 16 (1 address range) ? Read/Write Acceptance: 4 ? Read/Write Issuing: 8
? Arbitration Priority: 0 (round-robin) ? Single Thread: Disabled ? USER Width: 0
AXI Crossbar Performance: SASD, AXI4 Protocol
Common Configuration:
? Connectivity Mode: SASD (Minimize Area strategy) ? Protocol: AXI4 or AXI3
? Data Width: 64 or 256 (as noted) for Kintex-7, Virtex-7, and Zynq-7000; 64 for Artix-7 ? Read/Write Connectivity: all SI and MI read/write ? Thread ID Width: 0 (all SI)
? Address Width: Global = 32; per MI = 16 (1 address range) ? Read/Write Acceptance: 1 ? Read/Write Issuing: 1
? Arbitration Priority: 0 (round-robin) ? User Width: 0
AXI Crossbar Performance: SASD, AXI4-Lite Protocol
Common Configuration:
? Connectivity Mode: SASD (Minimize Area strategy) ? Protocol: AXI4-Lite ? Data Width: 32
? Read/Write Connectivity: all SI and MI read/write
? Address Width: Global = 32; per MI = 16 (1 address range) ? Read/Write Acceptance: 1 ? Read/Write Issuing: 1
? Arbitration Priority: 0 (round-robin)