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Ixiasoft
Visible to Intel only — GUID: sfo1410068148169
Ixiasoft
9.3.4. Functional Description of the Lightweight HPS-to-FPGA Bridge
The bridge master exposed to the FPGA fabric has a fixed data width of 32 bits. The slave interface of the bridge in the HPS logic has a fixed data width of 32 bits.
Use the lightweight HPS-to-FPGA bridge as a secondary, lower-performance master interface to the FPGA fabric. With a fixed width and a smaller address space, the lightweight bridge is useful for low-bandwidth traffic, such as memory-mapped register accesses to FPGA peripherals. This approach diverts traffic from the high-performance HPS-to-FPGA bridge, and can improve both register access latency and overall system performance.
Bridge Property | L3 Slave Interface | FPGA Master Interface |
---|---|---|
Data width |
32 bits |
32 bits |
Clock domain |
l4_mp_clk | h2f_lw_axi_clk |
Byte address width |
32 bits |
21 bits |
ID width |
12 bits |
12 bits |
Read acceptance |
16 transactions |
16 transactions |
Write acceptance |
16 transactions |
16 transactions |
Total acceptance |
32 transactions |
32 transactions |
The lightweight HPS-to-FPGA bridge has three master interfaces. The master interface connected to the FPGA fabric provides a lightweight interface from the HPS to custom logic in the FPGA fabric. The two other master interfaces, connected to the HPS-to-FPGA and FPGA-to-HPS bridges, allow you to access the GPV registers for each bridge.
The lightweight HPS-to-FPGA bridge also has a set of registers GPV to control the behavior of its four interfaces (one slave and three masters).
The GPV allows you to set the bridge’s issuing capabilities to support single or multiple transactions. The GPV also lets you set a write tidemark through the wr_tidemark register, to control how much data is buffered in the bridge before data is written to slaves in the FPGA fabric.