Xilinx System Generator v2.1 Reference Guide

Bit-True and Cycle-True Modeling

System Generator produces a hardware implementation that is bit and cycle true to the system level simulation. We define the term bit and cycle true at the boundaries of the design. The boundaries of a design in System Generator are specified by the presence of Gateway In and Gateway Out blocks. These form interfaces between data representation within System Generator and data types that can be examined and manipulated in the standard Simulink environment. The gateways are translated into ports in the implemented hardware design. The Gateway In blocks become input ports to the design and the Gateway Out blocks become output ports.

In the Simulink simulation, Gateway in and Out blocks have data samples flowing through at regular sample periods. The values flowing in provide the stimuli, and those flowing out represent the response. In the generated hardware, if an identical stimulus sequence is presented at the input ports (at clock events corresponding to the input sample periods), then identical output sequences will be observed (here at clock events corresponding to Simulink output events). The values presented to the hardware input ports and produced by the output ports are bit vectors interpreted as representing the fixed point values of the Simulink simulation. This correspondence between Simulink and hardware results is guaranteed to hold regardless of the particular input stimulus to the design or the positioning or number of Gateway Out blocks.

Automatic Testbench Generation

For a black box instantiation, the design must provide both a Simulink model and an implementation. System Generator cannot automatically provide the verification that the two representations of the black box match. To assist the designer in verifying that the system model simulated in Simulink mirrors the generated hardware circuit, a VHDL test bench is automatically created during HDL code generation.

Test bench input stimuli are recorded by Gateway In blocks during Simulink simulation. These blocks quantize double precision input date into a fixed point representation. The fixed point values are saved to a data file and then used as input stimuli during VHDL simulation.

Gateway Out blocks convert the fixed point representation into Simulink floating point and define the output data ports of the HDL design. The signal connected to the input of a Gateway In block is sampled at a given sample rate and is used as expected data in the HDL simulation.

During HDL code generation, each Gateway In block is translated to a VHDL component which reads the input stimuli. Gateway Out blocks are translated to components that compare the VHDL results to the expected results. The comparisons are performed at the blocks' sample rates. Only values which are tagged as valid by the valid bit are compared.

The fixed point data type in Simulink is represented using a std_logic_vector in VHDL. The position of the binary point, size of the container, and treatment of sign are supplied to the VHDL as generic parameters. To ease the interpretation of fixed point types in VHDL, the Gateway In and Out blocks convert the std_logic_vector into a real number representation by using the generic parameter information. A sequence of real numbers can then be viewed as an analog waveform in an HDL simulator.

14

Xilinx Development System

Page 13 Page 15
Page 14
Image 14
Xilinx V2.1 manual Bit-True and Cycle-True Modeling, Automatic Testbench Generation
Page 13 Page 15

V2.1 specifications

Xilinx V2.1 is a notable iteration in the series of versatile and robust Field-Programmable Gate Arrays (FPGAs) developed to cater to a wide range of applications. Launched to provide enhancements in performance and flexibility, V2.1 embodies sophisticated technologies and features that stand out in the electronics industry.

One of the primary features of Xilinx V2.1 is its improved processing power. The architecture has been optimized to support higher clock speeds and increased logic density, allowing for more complex designs to be implemented effectively. This boost in performance is facilitated by utilizing advanced silicon technologies, which significantly reduce power consumption while maximizing efficiency.

Another significant characteristic of Xilinx V2.1 is its enhanced I/O (Input/Output) capabilities. The device supports a variety of industry-standard interfaces, which include PCI Express, SATA, and various serial communication protocols. Such adaptability ensures seamless integration into existing systems, providing engineers with the flexibility to adapt to various application requirements without the need for substantial redesign efforts.

Xilinx V2.1 also features improved scalability, making it a prime choice for applications that demand diverse performance levels. This device supports an array of configurations and can be used in small-scale projects as well as in larger, more demanding environments requiring extensive resources. This scalability is further aided by support for multiple development platforms, enabling rapid prototyping and simplifying the design process.

Security is increasingly becoming a priority in digital design, and Xilinx V2.1 addresses this concern via hardware security features. It includes enhanced encryption protocols and secure boot functionalities, which help protect intellectual property and sensitive data from unauthorized access.

Additionally, the integration of advanced DSP (Digital Signal Processing) blocks allows Xilinx V2.1 to efficiently handle data-intensive tasks such as video processing and real-time signal analysis. These capabilities make it suitable for applications in telecommunications, automotive systems, and industrial automation.

Xilinx V2.1 also benefits from a rich development environment, including robust software tools that facilitate design entry, simulation, and verification. The support for industry-standard programming languages like VHDL and Verilog simplifies the development process, enabling engineers to design complex systems more efficiently.

In summary, Xilinx V2.1 stands out due to its impressive combination of high performance, flexibility, scalability, security, and comprehensive development support. These features make it a valuable asset for engineers and developers looking to innovate across various sectors, from telecommunications and automotive to industrial applications.
Top Page Image Contents