AV-51001
2013.05.06
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HPS–FPGA AXI Bridges
HPS–FPGA AXI Bridges
The HPS–FPGA bridges, which support the Advanced Microcontroller Bus Architecture (AMBA®) Advanced
eXtensible Interface (AXI™) specifications, consist of the following bridges:
• FPGA-to-HPS AXI bridge—a high-performance bus supporting 32, 64, and 128 bit data widths that
allows the FPGA fabric to issue transactions to slaves in the HPS.
• HPS-to-FPGA AXI bridge—a high-performance bus supporting 32, 64, and 128 bit data widths that
allows the HPS to issue transactions to slaves in the FPGA fabric.
• Lightweight HPS-to-FPGA AXI bridge—a lower latency 32 bit width bus that allows the HPS to issue
transactions to slaves in the FPGA fabric. This bridge is primarily used for control and status register
(CSR) accesses to peripherals in the FPGA fabric.
The HPS–FPGA AXI bridges allow masters in the FPGA fabric to communicate with slaves in the HPS logic,
and vice versa. For example, the HPS-to-FPGA AXI bridge allows you to share memories instantiated in the
FPGA fabric with one or both microprocessors in the HPS, while the FPGA-to-HPS AXI bridge allows logic
in the FPGA fabric to access the memory and peripherals in the HPS.
Each HPS–FPGA bridge also provides asynchronous clock crossing for data transferred between the FPGA
fabric and the HPS.
HPS SDRAM Controller Subsystem
The HPS SDRAM controller subsystem contains a multiport SDRAM controller and DDR PHY that are
shared between the FPGA fabric (through the FPGA-to-HPS SDRAM interface), the level 2 (L2) cache, and
the level 3 (L3) system interconnect. The FPGA-to-HPS SDRAM interface supports AMBA AXI and Avalon®
Memory-Mapped (Avalon-MM) interface standards, and provides up to six individual ports for access by
masters implemented in the FPGA fabric.
To maximize memory performance, the SDRAM controller subsystem supports command and data
reordering, deficit round-robin arbitration with aging, and high-priority bypass features. The SDRAM
controller subsystem supports DDR2, DDR3, or LPDDR2 devices up to 4 Gb in density operating at up to
533 MHz (1066 Mbps data rate).
FPGA Configuration and Processor Booting
The FPGA fabric and HPS in the SoC FPGA are powered independently. You can reduce the clock frequencies
or gate the clocks to reduce dynamic power, or shut down the entire FPGA fabric to reduce total system
power.
You can configure the FPGA fabric and boot the HPS independently, in any order, providing you with more
design flexibility:
• You can boot the HPS independently. After the HPS is running, the HPS can fully or partially reconfigure
the FPGA fabric at any time under software control. The HPS can also configure other FPGAs on the
board through the FPGA configuration controller.
• You can power up both the HPS and the FPGA fabric together, configure the FPGA fabric first, and then
boot the HPS from memory accessible to the FPGA fabric.
Note: Although the FPGA fabric and HPS are on separate power domains, the HPS must remain powered
up during operation while the FPGA fabric can be powered up or down as required.
Arria V Device Overview
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