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Using LUTs for array of coefficients

 
 
Bob
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      09-18-2003
Hello again,

I have an array of 16 10 bit coefficients, and I would like to store
these in LUT on an FPGA instead of Flops. Can I do this in Xilinx and
Altera devices by selecting various options say on Quartus, or can I
switch on any synthesis switches or do I have to change my VHDL. Any ideas
as always is greatly appreciated.

Thanks
Bob
 
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Jim Lewis
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      09-18-2003
Bob,
If your coefficients are constants and you use those
constants in your design, there is nothing to store.
During synthesis the constants reduce to pull-up and
pull-down and then further optimize away portions of
the circuit.

If your coefficients are not constants, then they would
need to be stored in either a register or a RAM.
If use a register coding style for your coefficients, then
they will be realized in a LUT.

If you need further help, you may wish to either further
describe your problem or post your code.

Cheers,
Jim Lewis
--
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ ~~~~~~~~~~~
Jim Lewis
Director of Training private.php?do=newpm&u=
SynthWorks Design Inc. http://www.SynthWorks.com
1-503-590-4787

Expert VHDL Training for Hardware Design and Verification
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ ~~~~~~~~~~~

Bob wrote:

> Hello again,
>
> I have an array of 16 10 bit coefficients, and I would like to store
> these in LUT on an FPGA instead of Flops. Can I do this in Xilinx and
> Altera devices by selecting various options say on Quartus, or can I
> switch on any synthesis switches or do I have to change my VHDL. Any ideas
> as always is greatly appreciated.
>
> Thanks
> Bob


 
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