Discover New Applications For Low-Cost Solutions Discover ... - Xilinx
Discover New Applications For Low-Cost Solutions Discover ... - Xilinx
Discover New Applications For Low-Cost Solutions Discover ... - Xilinx
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You can control PALACE operations in<br />
the standard flow by a simple four-level<br />
effort option.<br />
The effort level determines how aggressively<br />
the PALACE tool will try to optimize<br />
your design, with the first level optimizing<br />
for minimum area utilization and the<br />
remaining levels optimizing for maximum<br />
performance. The default level is the third<br />
level, and it is the initial recommended<br />
level when performance is an issue.<br />
After specifying the effort level, no further<br />
user intervention is required. Using<br />
PALACE technology in this flow provides<br />
you with the advantages of physical synthesis<br />
in a simple push-button automated<br />
flow, and can meet most realistic design<br />
requirements.<br />
Guided Flow<br />
You can use the PALACE tool in the guided<br />
flow for Virtex-II devices to achieve the<br />
incremental improvements needed to<br />
meet your design requirements. In this<br />
flow, you first generate an NCD (native<br />
circuit description) file by placing and<br />
routing your design. This NCD file is<br />
then converted to XDL (<strong>Xilinx</strong> Design<br />
Language) format with the <strong>Xilinx</strong> XDL<br />
utility and passed as an input to the<br />
PALACE program, along with the design<br />
constraint file. The PALACE tool optimizes<br />
the paths that do not meet timing<br />
requirements to help you achieve timing<br />
closure. As with the standard flow, an<br />
optimized netlist and constraint file is<br />
produced that you use in the rest of your<br />
design flow.<br />
You can control PALACE operation in<br />
the guided flow by a simple two-level effort<br />
Category (Design) Spartan-3 Device<br />
option, which determines how aggressively<br />
the PALACE program will try to optimize<br />
your design. As with the standard flow, no<br />
further user intervention is required. Using<br />
PALACE physical synthesis in the guided<br />
flow provides you with the capabilities of<br />
an advanced physical synthesis solution in<br />
a simple push-button automated flow.<br />
Thus, you can meet the “last mile” performance<br />
requirements of your design.<br />
Achieving Best Results with PALACE<br />
Effective use of the PALACE physical synthesis<br />
solution can help you meet your<br />
design requirements quickly. With the<br />
standard and guided flows, you have two<br />
simple but powerful solutions that should<br />
be used together in order to achieve the<br />
best results.<br />
When you use the PALACE engine in<br />
either flow, you should always include timing<br />
constraints in the input constraint file.<br />
Meaningful and accurate timing constraints<br />
are important because they help the<br />
PALACE program to focus on the problem<br />
areas of your design, while allowing tradeoffs<br />
with other non-critical areas.<br />
If you are particularly concerned about<br />
area utilization, you should use the first<br />
effort level on your initial run. Otherwise,<br />
you should use the default settings, which<br />
will automatically run PALACE physical<br />
synthesis in standard flow at a highoptimization<br />
effort level.<br />
After you have obtained the optimized<br />
results, you can analyze either the<br />
PALACE report file or the report from an<br />
implementation run to determine if the<br />
result meets your requirements. If you miss<br />
your timing targets by a wide margin<br />
Performance Gain<br />
(% Max Frequency)<br />
DSP (DES) XC3S400FT256-4 37%<br />
Microcontrollers (uP1232a) XC3S200FT256-4 28%<br />
Communications (Reed-Solomon decoder) XC3S200PQ408-4 8%<br />
Bus Interfaces (I 2 C Master) XC3S50PQ208-4 12%<br />
State Machine and Control Logic (Arbiter) XC3S400FT256-4 93%<br />
Table 1 – Examples of PALACE performance improvements<br />
(more than a few nanoseconds in Spartan-<br />
3 devices), you should try running the<br />
PALACE engine in the standard flow with<br />
a higher effort level. If you are using a<br />
Virtex-II device and have still not met<br />
timing requirements, you should try the<br />
guided flow to achieve the last nanosecond<br />
or so of required performance.<br />
The performance gains that you obtain<br />
with PALACE physical synthesis will vary<br />
depending on the type and complexity of<br />
the design. Table 1 shows performance<br />
improvements obtained when the PALACE<br />
solution was used in the standard flow for a<br />
few sample designs from a variety of categories.<br />
In all of these cases, the design flow<br />
was identical for two runs, except that the<br />
PALACE solution was used before the<br />
implementation stage in the second run. As<br />
you can see, PALACE physical synthesis<br />
provides a substantial increase in performance<br />
that allows you to move to a slower<br />
speed grade in many cases.<br />
Conclusion<br />
As FPGAs continue to increase in density<br />
and complexity, you need to ensure that<br />
your tools extract the maximum potential of<br />
the device’s architecture in the minimum<br />
amount of time. This is especially true for<br />
cost-sensitive design cycles that involve the<br />
low-cost Spartan-3 FPGAs. Without a physical<br />
synthesis solution that can effectively<br />
exploit the architecture of your target device,<br />
you risk overrunning your forecasted costs<br />
by having to move to a more expensive part,<br />
or by spending too many engineering hours<br />
trying to achieve timing closure.<br />
The Aplus PALACE tool is an<br />
advanced physical synthesis solution that<br />
fits seamlessly within your existing design<br />
flow for all <strong>Xilinx</strong> Spartan-II, Spartan-IIE,<br />
Spartan-3, Virtex, Virtex-E, Virtex-II, and<br />
Virtex-II Pro FPGAs, providing you<br />
with a fully automated solution to help<br />
achieve your design requirements in the<br />
minimum amount of time. In fact, you<br />
may even be able to move to a smaller part<br />
or a slower speed grade and dramatically<br />
reduce your costs.<br />
To learn more about the PALACE physical<br />
synthesis tool, e-mail info@aplusdt.com<br />
or visit www.aplus-dt.com.<br />
Fall 2003 Xcell Journal 13