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AR# 17809

LogiCORE PCI-X - Can a PCI-X design plug into a 133, 100, or 66 MHz bus or do I need separate bit files? In what modes does the PCI-X Core operate?

Description

General Description:

- Can a PCI-X design plug into a 133-, 100-, or 66-MHz PCI-X bus, or do I need separate bit files?

- What if I need PCI backwards-compatibility?

- What modes does the PCI-X Core operate in?

Solution

The PCI-X LogiCORE operates in one of the following three modes (each one requires a single bitstream):

- PCI mode only at 33 MHz

- PCI-X mode only up to 133 MHz

- Dual Mode - PCI at 33 MHz and PCI-X at 66 MHz (NOTE: Not available in the Virtex-4 device)

The different modes of operation are determined by the correct wrapper, configuration, and UCF files, along with the correct core file. For more information on the suffix designation of files in the PCI-X Core deliverable, refer to (Xilinx Answer 18951).

The following two versions of the PCI-X Core are located in the <install path>/verilog/src/xpci or <install path>/vhdl/src/xpci directory:

- pcix_fast.ngo

- pcix_core.ngc

The pcix_fast.ngo file is used for PCI-X mode only designs operating up to 133 MHz in the Virtex-II and Virtex-II Pro.

The pcix_core.ngc file is used for PCI mode only designs operating up to 33 MHz and for dual-mode designs that operate in PCI mode at 33 MHz and PCI-X mode at 66 MHz in the Virtex-II and Virtex-II Pro. This file is also used for PCI-X mode only designs operating up to 133 MHz in the Virtex-4.

For more information on operation modes, refer to Table 3-1 in the PCI-X Getting Started Guide found in the <install path>/docs directory of the PCI-X core download or at:

http://www.xilinx.com/xlnx/xebiz/designResources/ip_product_details.jsp?key=DO-DI-PCIX-V5

Each mode of operation requires specific settings in the configuration file. Refer to the "Special Configuration Options" section in the "Customizing the LogiCORE PCI-X Interface" chapter in the PCI-X Core User's Guide, located in the <install path>/docs directory or at:

http://www.xilinx.com/xlnx/xebiz/designResources/ip_product_details.jsp?key=DO-DI-PCIX-V5

Examples

The following are some examples of how to use the different core combinations:

1. I want to design a PCI-only system operating at 33 MHz using the v5.0 PCI-X LogiCORE. How can I do this?

Use the PCI-X Core running in PCI-only mode. You should use the "pcix_core.ngc" file, along with the other PCI-mode only files, as described in (Xilinx Answer 18951) and in the PCI-X Core Getting Started Guide.

2. I want to design a PCI-X mode only design operating at 100 MHz in a Virtex-II or Virtex-II Pro? How can I do this?

Use the PCI-X Core running in PCI-X mode only. You should use the "pcix_fast.ngo" file, along with the other PCI-X fast mode only files, as described in (Xilinx Answer 18951) and in the PCI-X core Getting Started Guide.

Instructions for changing the timing constraints from 133 MHz to 100 MHz are included in the UCF file.

3. I want to create a design that operates at 66 MHz PCI-X mode and 33 MHz PCI mode in a Virtex-II or Virtex-II Pro. How can I do this?

Use the PCI-X Core running in dual mode. You should use the "pcix_core.ngc" file, with the other dual mode operation files, as described in (Xilinx Answer 18951) and in the PCI-X Core Getting Started Guide.

4. I want to create a design that operates at 133 MHz or 100 MHz PCI-X mode and operates at 33 MHz PCI mode in a Virtex-II or Virtex-II Pro. How can I do this?

This design requires two bitstreams on the board. One of the bitstreams is capable of operating at 133 MHz or 100 MHz PCI-X mode only using the "pcix_fast.ngo" file, while the other operates in 33 MHz PCI mode only using the "pcix_core.ngc" file.

This design makes use of the reconfiguration (RTR) feature of the core. For more information, refer to the PCI-X LogiCORE User's Guide in the <install path>/docs directory or at:

http://www.xilinx.com/xlnx/xebiz/designResources/ip_product_details.jsp?key=DO-DI-PCIX-V5

5. I want to create a PCI-X mode only design running at 133 MHz in a Virtex-4. How can I do this?

Use the PCI-X Core running in PCI-X mode only. You should use the "pcix_core.ngc" file, along with the other PCI-X mode only files, as described in (Xilinx Answer 18951) and in the PCI-X Core Getting Started Guide.

6. I want to create a design that operates in both 33 MHz PCI and PCI-X mode up to 133 MHz in a Virtex-4. How can I do this?

This design requires two bitstreams on the board. One of the bitstreams is capable of operating at 133 MHz or 100 MHz PCI-X mode only using the "pcix_core.ngc" file. The other operates in 33 MHz PCI mode only also using the "pcix_core.ngc" file. Even though both designs use the same core file, they are differentiated through the use of the wrapper and UCF files. Refer to (Xilinx Answer 18951) and the PCI-X Core Getting Started Guide.

7. I want to create a 66 MHz PCI mode only design, or a design that operates in PCI-X mode and also in 66 MHz PCI mode. How can I do this?

If at any time, you want to design for a system that could potentially operate at 66 MHz PCI and you want your design to be able to operate at this speed, you must use the v3.0 PCI LogiCORE for that portion of the design. If you also need PCI-X mode operation, then you need two bitstreams; one using the v5.0 PCI-X Core and one using the v3.0 PCI Core. For more information on the v3.0 PCI Core, refer to:

http://www.xilinx.com/products/design_resources/conn_central/grouping/pcix.htm

AR# 17809
Date Created 09/03/2007
Last Updated 12/15/2012
Status Active
Type General Article