Xilinx Virtex 4 question

Austin Lesea wrote:
> 
> Tom,
> 
> There is a SDR project that uses partial reconfiguration to load the
> differing modulation/demodulation formats.  They use a form of file
> system to represent the FPGA (I have seen it, it is realy neat -- you
> can look at the FPGA using a browser, and it looks like a file system).
> 
> Connections to and from the reloadable modules are simply hard loc'd
> interconnect paths (each modem uses the same inputs and outputs).

Do you have any idea of where the Spartan 3 fits into the plans for
partial reconfiguration?  Is it seriously being developed or is it still
very back burner?  

-- 

Rick "rickman" Collins

rick.collins@XYarius.com
Ignore the reply address. To email me use the above address with the XY
removed.

Arius - A Signal Processing Solutions Company
Specializing in DSP and FPGA design      URL http://www.arius.com
4 King Ave                               301-682-7772 Voice
Frederick, MD 21701-3110                 301-682-7666 FAX

Rick,

TBUFs are not required for partial reconfiguration.  That was just one 
approach.  We do not have real TBUFs anyway (they were really gates 
fooling everyone into thinking they are tristate busses).

As far as the tools supporting it, you are correct:  the tools do not 
support it.

However, using the tools, and hand placements, one can do it (although 
painfully) using any interconnect you like with great care (and time).

The key to this is a set of new tools that allow for replaceable modular 
design, and fixed communication pipes to be built.

Austin

Rick,

Frankly, the Spartan team is not all that concerned about the (partial) 
reconfiguration feature.  I understand your situation, and I can 
sympathize, but the "low cost" FPGA is diverging from the "high feature" 
FPGA.

We see more and more decisions being made that begin to seriously 
differentiate the two product lines.

Spartan 3 may be the last part that looks in large part very similar to 
a 'Virtex' part.

Is this good?  Well, all I can say is that they seem to be selling a 
hell of a lot of parts (some joke that the 'Spartan products group' is 
now the second largest FPGA vendor - by number of parts shipped - in the 
world!).

I would ask your contact at the factory about their plans in their new 
family.  They may decide to support it, or not.

Austin



rickman wrote:
> Austin Lesea wrote:
> 
>>Tom,
>>
>>There is a SDR project that uses partial reconfiguration to load the
>>differing modulation/demodulation formats.  They use a form of file
>>system to represent the FPGA (I have seen it, it is realy neat -- you
>>can look at the FPGA using a browser, and it looks like a file system).
>>
>>Connections to and from the reloadable modules are simply hard loc'd
>>interconnect paths (each modem uses the same inputs and outputs).
> 
> 
> Do you have any idea of where the Spartan 3 fits into the plans for
> partial reconfiguration?  Is it seriously being developed or is it still
> very back burner?  
> 

Austin Lesea wrote:
> 
> Rick,
> 
> Frankly, the Spartan team is not all that concerned about the (partial)
> reconfiguration feature.  I understand your situation, and I can
> sympathize, but the "low cost" FPGA is diverging from the "high feature"
> FPGA.

I guess I don't understand how this is an issue.  The current parts
support partial reconfiguration in hardware.  Even if it is not
supported in hardware, a bitstream can be "modular" which would suffice
to meet my needs.  But it has to be supported in software.  That is the
issue for the Spartan 3 parts, not the hardware. 


> I would ask your contact at the factory about their plans in their new
> family.  They may decide to support it, or not.

I did, but just like a year ago, I got an answer that says it is in the
plan, but no dates are given.  

Frankly I don't see why this is an issue for the Virtex but not the
Spartan devices.  Using the modular reconfiguration capability of an
FPGA can provide temendous compression of bitstream data if the design
is truely modular.  One of the big marketing/selling points of FPGAs is
that the same hardware can be used to do different tasks at different
times by reconfiguring them.  The idea of modular configuration is just
an extension of that to allow greater saving in hardware costs.  

If Sirius wanted to use an FPGA as an SDR with modular reconfiguration,
do you think they would want to pay $50 for a Virtex or <$20 for a
Spartan part?  

-- 

Rick "rickman" Collins

rick.collins@XYarius.com
Ignore the reply address. To email me use the above address with the XY
removed.

Arius - A Signal Processing Solutions Company
Specializing in DSP and FPGA design      URL http://www.arius.com
4 King Ave                               301-682-7772 Voice
Frederick, MD 21701-3110                 301-682-7666 FAX

Rick,

I will forward this thread to my buddy in Spartan land.

I'm on your side here.

But the XC4VLX15 is not going to be a $50 part, and at 13,824 logic 
cells, 864 Kb of BRAM, 32 DSP48's, and four DCM's, that might be just 
the right choice for a SDR design.  I think that a Spartan part that 
could do the same thing would be much larger, and probably more costly 
just due to the lack of the hard IP?

But, you are right:  whatever solves the problem is going to win, and if 
Spartan could have had the socket if they had made some other decisions, 
maybe that would be a good thing.

I'll let you know what kind of response I get.

Austin

rickman wrote:
> Austin Lesea wrote:
> 
>>Rick,
>>
>>Frankly, the Spartan team is not all that concerned about the (partial)
>>reconfiguration feature.  I understand your situation, and I can
>>sympathize, but the "low cost" FPGA is diverging from the "high feature"
>>FPGA.
> 
> 
> I guess I don't understand how this is an issue.  The current parts
> support partial reconfiguration in hardware.  Even if it is not
> supported in hardware, a bitstream can be "modular" which would suffice
> to meet my needs.  But it has to be supported in software.  That is the
> issue for the Spartan 3 parts, not the hardware. 
> 
> 
> 
>>I would ask your contact at the factory about their plans in their new
>>family.  They may decide to support it, or not.
> 
> 
> I did, but just like a year ago, I got an answer that says it is in the
> plan, but no dates are given.  
> 
> Frankly I don't see why this is an issue for the Virtex but not the
> Spartan devices.  Using the modular reconfiguration capability of an
> FPGA can provide temendous compression of bitstream data if the design
> is truely modular.  One of the big marketing/selling points of FPGAs is
> that the same hardware can be used to do different tasks at different
> times by reconfiguring them.  The idea of modular configuration is just
> an extension of that to allow greater saving in hardware costs.  
> 
> If Sirius wanted to use an FPGA as an SDR with modular reconfiguration,
> do you think they would want to pay $50 for a Virtex or <$20 for a
> Spartan part?  
>