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Chapter 4: Designing with the Core

Keep it Registered

The best method to simplify timing and increase system performance in an FPGA design is to keep everything registered. That is, all inputs and outputs from the user application should come from, or connect to, a flip-flop. While registering signals may not be possible for all paths, it simplifies timing analysis and helps you achieve timing closure.

Recognize Timing Critical Signals

Watch the timing and loading on the signals listed below. Some of these signals are part of the critical timing path. The following list of signals are timing critical and may require special attention when used in the user application:

SnkFFRdEn_n

SrcFFWrEn_n

Use Supported Design Flows

The SPI-4.2 Lite core has been tested with a variety of design flows. While other design tools can be used to simulate and synthesize your design with the core, their functionality cannot be guaranteed. See Chapter 7, “Simulating and Implementing the Core” for information about supported design tools.

Make Only Allowed Modifications

All modifications to the SPI-4.2 Lite core must be made using the Xilinx CORE Generator. Do not make other modifications as they may have adverse effects on system timing and SPI-4.2 protocol compliance.

Initializing the SPI-4.2 Lite Core

The SPI-4.2 Lite Sink and Source cores require initialization before receiving and transmitting data. The initialization steps are:

Reset core

To reset the cores, the signal Reset_n must be asserted. The reset signal for each core must remain asserted until the clocks are ready for use.

Reset DCMs

This step is only applicable if TDClk or RDClk is distributed using global clocking. The DCMs are only used when the global clocking option is selected. If regional clocking is selected for all clocks, this step can be skipped. If one or more DCMs are used, you must reset each DCM in the core while the core is in reset. Reset the DCM by asserting the DCM reset signal (ex: DCMReset_RDClk). Once the DCM reset is asserted, wait for the assertion of the DCM locked signal (ex: Locked_RDClk). When the locked signal is asserted, the clock is ready for use.

See “Sink Clocking Options,” page 111 and “Source Clocking Options,” page 115 for more information on the regional and global clocking options

Deassert core reset

Once all the clocks are ready for use, the SnkClksRdy and SrcClksRdy signals will assert. The Reset_n signal can be deasserted only when these signals are asserted.

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SPI-4.2 Lite v4.3 User Guide

 

 

UG181 June 27, 2008

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Xilinx UG181 manual Initializing the SPI-4.2 Lite Core, Keep it Registered, Recognize Timing Critical Signals

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.

Furthermore, these FPGAs offer extensive memory options, including support for a wide range of external memory interfaces. This versatility allows for the integration of high-bandwidth memory solutions, which is essential for performance-intensive applications. With the introduction of the Memory Controller IP, users can easily connect various memory types, ensuring flexibility in system design.

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.