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Chapter 5: Constraining the Core

INST "<snk_instance_name>/U0/clk0/rdclk_dcm0" IOBDELAY_VALUE = 0;

Placement Constraints

Although the SPI-4.2 Lite core does not require fixed pinouts, there are several placement constraints that are critical to meet performance requirements and process through the Xilinx tools. The constraints generated in the CORE Generator system is only an example and should be modified. The user can modify these constraints to:

Move the core placement to a different area

Target a different device (other than the example device package configuration)

See Constraints Migration Guide for information on how to migrate the core to a different area or device-package.

I/O Placement

In SPI-4.2 Lite core, the user has the flexibility to place the SPI-4.2 Lite I/Os according to their needs. The user is not restricted to place the I/Os in the bank options provided in the GUI. The placement of the I/Os can be defined using 2 kinds of constraints: bank or pin- lock constraints.

The following is an example of how to define I/O bank constraints:

INST "RCtl*" LOC = "Bank5"; # 1 LVDS I/O pair

INST "RDat*" LOC = "Bank5"; # 16 LVDS I/O pairs

Note that all the SPI-4.2 Lite I/Os do not need to be in a single bank as given in the example UCF. Ensure that there are enough I/Os in the targeted bank (or banks) when using these constraints.

The following is an example of how to define I/O pin lock constraints:

NET "RDat_P(15)" LOC = "G18";

NET "RDat_P(14)" LOC = "B24";

NET "RDat_P(13)" LOC = "F18";

NET "RDat_P(12)" LOC = "E21";

NET "RDat_P(11)" LOC = "A20";

NET "RDat_P(10)" LOC = "D22";

To use these constraints, add the constraints and modify the pinout accordingly. If you use an area group to define the placement of the Sink core, place the SPI-4.2 Lite pins (RCtl and RDat) in the same clock region as the defined area group. This is especially needed if regional clocking is used.

The user also has the same flexibility of placing RDClk using the above constraints type. However, there are some general guidelines when using different clocking options.

If regional clocking is chosen, RDClk must be placed on a clock capable I/O pin that is in the same clock region as the Lite Sink core logic.

To illustrate, in the example UCF file:

INST "RDClk" LOC = "Bank5";

If global clocking is chosen, RDClk must be placed on a pin that is connected to a global clock buffer. For instance, in the example UCF file:

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SPI-4.2 Lite v4.3 User Guide

 

 

UG181 June 27, 2008

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Xilinx UG181 manual Placement Constraints

UG181 specifications

Xilinx UG181 refers to the User Guide for the Xilinx 7 Series FPGAs, which offers a comprehensive overview of the architecture, capabilities, and features of these powerful field-programmable gate arrays (FPGAs). Designed to cater to a wide range of applications, Xilinx 7 Series FPGAs are widely adopted in industries such as telecommunications, automotive, aerospace, and consumer electronics.

One of the main features of the Xilinx 7 Series FPGAs is their use of advanced 28nm technology, which enables them to achieve high performance while maintaining low power consumption. This fine process technology not only ensures better power efficiency but also allows for increased logic density. The 7 Series includes several families, such as Artix-7, Kintex-7, and Virtex-7, each tailored for specific application demands ranging from cost-sensitive solutions to high-performance data processing.

Xilinx 7 Series FPGAs also incorporate a rich set of programmable logic resources. This includes Look-Up Tables (LUTs), Flip-Flops, and Digital Signal Processing (DSP) slices that have been optimized for various arithmetic functions. With several thousands of logic cells available, designers can implement complex algorithms and systems directly in hardware for improved performance over traditional software solutions.

In addition to their logic capabilities, Xilinx 7 Series FPGAs feature an array of high-speed serial communication interfaces. These include support for technologies like PCI Express, Gigabit Ethernet, and Serial RapidIO, which facilitate efficient data transfer and integration into enterprise-level systems. The presence of high-speed transceivers also makes them ideal for applications that require fast data handling like video processing or high-frequency trading.

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Finally, Xilinx has made significant strides in development tools for 7 Series FPGAs, providing a robust ecosystem for design engineers. With design suites such as Vivado and SDK, users benefit from a comprehensive platform for deciding, simulating, and implementing designs efficiently. The combination of advanced hardware capabilities and powerful software tools solidifies the position of Xilinx 7 Series FPGAs as a preferred choice for custom digital hardware design across various industries.