Prev: Xilinx tools in Windows or Linux - Suggestions
Next: RAM and shift register constraints
From: fmostafa on 25 Jun 2008 10:39
hi all;

I am using HWICAP to configure certain LUTs , and as mentioned in the
HWICAP data sheet that "when LUTs are configured in Shift Register
Mode or as a RAM. If a LUT is modified or just read back in a column
that also has a LUT RAM or LUT shift register, then the LUT or shift
register will be interrupted and it will lose its state. To resolve
the problem, the LUT shift registers and LUT RAMs should be placed in
columns that are not read back or modified. " ,what i know form the
beginning is the instance name of the LUTs , is it possible to add
constrains to avoid placing these LUTs in columns that contain RAMs
or Shift registers, or may be there is another solution.

thanks

From: austin on 25 Jun 2008 10:44
fmostafa,

Which family?

In V5, we have an added bit in the bitstream which prevents LUTRAM and
SRL16/32 from being readback. The function performed is called GLUTMASK
(not that it matters what it is called). It was added just so you do
not have to deal with "knowing" which LUT are not to be disturbed (by a
readback/verify).

Austin
 | 
Pages: 1
Prev: Xilinx tools in Windows or Linux - Suggestions
Next: RAM and shift register constraints