LFSR in xilinx 13.2

Thu Sep 15, 2011 7:38 pm   

Hi,
I am using xilinx 13.2 for my design synthesis and i want to use xilinx I
for LFSR but i cannot find it in core gen. I am using Spartan3 xc3s400
FPGA.

Does anyone know where i can find it?


regards


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Thu Sep 15, 2011 8:47 pm   

On Thu, 15 Sep 2011 14:38:33 -0500, salimbaba wrote:


The actual LFSR description should take two or three lines, and it's not
the kind of thing that needs superhuman effort to optimize, particularly
if it's an internal XOR type.

An extern XOR type with a whole lot of taps might benefit from some
pipelining, but even that shouldn't be too hard.

So maybe they didn't think they needed to bother.

--
www.wescottdesign.com

Fri Sep 16, 2011 5:15 am   

Hi,

Here is the link to online LFSR code generator:

http://outputlogic.com/?page_id=275

Thanks,
Evgeni

Fri Sep 16, 2011 6:55 am   

"salimbaba" <a1234573_at_n_o_s_p_a_m.n_o_s_p_a_m.owlpic.com> wrote in message
news:H7-dnYe-8Nqkye_TnZ2dnUVZ_t-dnZ2d_at_giganews.com...

http://www.xilinx.com/support/documentation/application_notes/xapp052.pdf

Fri Sep 16, 2011 2:35 pm   

On Sep 15, 2:38 pm, "salimbaba"
<a1234573_at_n_o_s_p_a_m.n_o_s_p_a_m.owlpic.com> wrote:

In all ISE releases you can find example designs. XAPP211: PN
Generator, is one I authored years ago. There's a verilog and VHDL
version. A PN Generator is basically an LFSR. There should be enough
comments in the code to explain how to infer SRL16s (vs FFs). Here're
some other docs in case you're interested...

Pseudo-random Noise Generators using SRLs (app note and reference
design):
(http://www.xilinx.com/support/documentation/application_notes/
xapp211.pdf)

HDL Coding for PN Generators:
(http://www.nalanda.nitc.ac.in/industry/appnotes/xilinx/documents/
xcell/xl35/xl35_44.pdf)


Good luck,
Mike
www.fpgaace.com