Virtex-E 1.8 V Field Programmable Gate Arrays
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DS022-2 (v3.0) March 21, 2014
Module 2 of 4
Production Product Specification
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Development System
Virtex-E FPGAs are supported by the Xilinx Foundation and
Alliance Series CAE tools. The basic methodology for
Virtex-E design consists of three interrelated steps: design
entry, implementation, and verification. Industry-standard
tools are used for design entry and simulation (for example,
Synopsys FPGA Express), while Xilinx provides proprietary
architecture-specific tools for implementation.
The Xilinx development system is integrated under the
Xilinx Design Manager (XDM) software, providing design-
ers with a common user interface regardless of their choice
of entry and verification tools. The XDM software simplifies
the selection of implementation options with pull-down
menus and on-line help.
Application programs ranging from schematic capture to
Placement and Routing (PAR) can be accessed through the
XDM software. The program command sequence is gener-
ated prior to execution, and stored for documentation.
Several advanced software features facilitate Virtex-E design.
RPMs, for example, are schematic-based macros with relative
location constraints to guide their placement. They help
ensure optimal implementation of common functions.
For HDL design entry, the Xilinx FPGA Foundation develop-
ment system provides interfaces to the following synthesis
design environments.
Synopsys (FPGA Compiler, FPGA Express)
Exemplar (Spectrum)
Synplicity (Synplify)
For schematic design entry, the Xilinx FPGA Foundation
and Alliance development system provides interfaces to the
following schematic-capture design environments.
Mentor Graphics V8 (Design Architect, QuickSim II)
Viewlogic Systems (Viewdraw)
Third-party vendors support many other environments.
A standard interface-file specification, Electronic Design
Interchange Format (EDIF), simplifies file transfers into and
out of the development system.
Virtex-E FPGAs are supported by a unified library of stan-
dard functions. This library contains over 400 primitives and
macros, ranging from 2-input AND gates to 16-bit accumu-
lators, and includes arithmetic functions, comparators,
counters, data registers, decoders, encoders, I/O functions,
latches, Boolean functions, multiplexers, shift registers, and
barrel shifters.
The “soft macro” portion of the library contains detailed
descriptions of common logic functions, but does not con-
tain any partitioning or placement information. The perfor-
mance of these macros depends, therefore, on the
partitioning and placement obtained during implementation.
RPMs, on the other hand, do contain predetermined parti-
tioning and placement information that permits optimal
implementation of these functions. Users can create their
own library of soft macros or RPMs based on the macros
and primitives in the standard library.
The design environment supports hierarchical design entry,
with high-level schematics that comprise major functional
blocks, while lower-level schematics define the logic in
these blocks. These hierarchical design elements are auto-
matically combined by the implementation tools. Different
design entry tools can be combined within a hierarchical
design, thus allowing the most convenient entry method to
be used for each portion of the design.
Design Implementation
The place-and-route tools (PAR) automatically provide the
implementation flow described in this section. The parti-
tioner takes the EDIF net list for the design and maps the
logic into the architectural resources of the FPGA (CLBs
and IOBs, for example). The placer then determines the
best locations for these blocks based on their interconnec-
tions and the desired performance. Finally, the router inter-
connects the blocks.
The PAR algorithms support fully automatic implementation
of most designs. For demanding applications, however, the
user can exercise various degrees of control over the pro-
cess. User partitioning, placement, and routing information
is optionally specified during the design-entry process. The
implementation of highly structured designs can benefit
greatly from basic floor planning.
The implementation software incorporates Timing Wizard
timing-driven placement and routing. Designers specify tim-
ing requirements along entire paths during design entry.
The timing path analysis routines in PAR then recognize
these user-specified requirements and accommodate them.
Timing requirements are entered on a schematic in a form
directly relating to the system requirements, such as the tar-
geted clock frequency, or the maximum allowable delay
between two registers. In this way, the overall performance
of the system along entire signal paths is automatically tai-
lored to user-generated specifications. Specific timing infor-
mation for individual nets is unnecessary.
Design Verification
In addition to conventional software simulation, FPGA users
can use in-circuit debugging techniques. Because Xilinx
devices are infinitely reprogrammable, designs can be veri-
fied in real time without the need for extensive sets of soft-
ware simulation vectors.
The development system supports both software simulation
and in-circuit debugging techniques. For simulation, the
system extracts the post-layout timing information from the
design database, and back-annotates this information into
the net list for use by the simulator. Alternatively, the user
can verify timing-critical portions of the design using the
TRCE static timing analyzer.