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Old 04-18-2006, 03:03 PM
Gabor
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Default Re: Implementation of cascadable shift register in virtex FPGA

Prav,

It is common practice to draw simplified block diagrams without the
clock connection when all components are clocked from the same
source. The blocks shown in the Virtex 2 user guide are each
SRLC16, which have a Q output for variable delay plus a Q15
output for cascading. When connecting in a long variable shifter
design, normally the Q15 output is attached to the next SRLC16
and the Q outputs are multiplexed using the upper bits of the
delay as the selector. Then the lower 4 bits of the desired delay
can route to all SRLC16's in the chain.

Regards,
Gabor

prav wrote:
> Hi all,
>
> I was going through the datasheet of virtex2 , in which i read that
>
> "each 4-input function generator is programmable as a 4-input LUT, 16
> bits of distributed SelectRAM memory, or a 16-bit variable- bits of
> distributed SelectRAM memory, or a 16-bit variable-tap shift register
> element."
>
> In the diagrams given in the viretx2 datasheet for cascadable shift
> register , i don't seen any clock at all.
>
> Can anybody clarify on this implementation???
>
> Regards,
> Prav


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