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Description
Direction
Width
Signal
Read data channel valid
Input
1 bit
RVALID
Read data channel ready
Output
1 bit
RREADY
Lightweight HPS-to-FPGA Bridge
The lightweight HPS-to-FPGA bridge provides a lower-performance interface to the FPGA fabric. This
interface is useful for accessing the control and status registers of soft peripherals. The bridge provides a
2 MB address space and access to logic, peripherals, and memory implemented in the FPGA fabric. The
MPU subsystem, direct memory access (DMA) controller, and debug access port (DAP) can use the lightweight
HPS-to-FPGA bridge to access the FPGA fabric or GPV. Master interfaces in the FPGA fabric can also use
the lightweight HPS-to-FPGA bridge to access the GPV registers in all three bridges.
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 CSR access latency and overall system
performance.
The following table lists the properties of the lightweight HPS-to-FPGA bridge, including the master interface
exposed to the FPGA fabric.
Table 5-15: Lightweight HPS-to-FPGA Bridge Properties
FPGA Master Interface
L3 Slave Interface
Bridge Property
32 bits
32 bits
Data width
h2f_lw_axi_clk
l4_mp_clk
Clock domain
21 bits
32 bits
Byte address width
12 bits
12 bits
ID width
16 transactions
16 transactions
Read acceptance
16 transactions
16 transactions
Write acceptance
32 transactions
32 transactions
Total acceptance
The lightweight HPS-to-FPGA bridge has three master interfaces, as shown in
AXI Bridges Block Diagram
and System Integration
. 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 GPV to control the behavior of its four interfaces (one slave
and three masters). The GPV is described in
The Global Programmers View
.
HPS-FPGA AXI Bridges
Altera Corporation
cv_54005
Lightweight HPS-to-FPGA Bridge
5-10
2013.12.30