Is there an obvious way to prevent an FPGA multiply from using DSPs?

[marcg33b]

This document (accessed via the corrected links below) is no longer available in the knowledgebase. Can you (re)post it somwhere accessible?

Also, is there a difference between using high throughput multiply and multiply outside a single cycle timed loop in terms of DSP48E slice usage?

[DanC12]

Hi marcg33b,

I'm unsure which link you are referring to. Can you repost the link and I will have a look.

[marcg33b]

Sorry, I didn't realize the forum doesn't preserve the message thread.

the link is from the message below

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Hi Thoric,

Just incase you miss the link from the CAR, here is a KB detailing how to make the compiler use resources other than DSP48E slices to implement multipliers

How Can I Work Around the "Too many comps of type 'DSP48E' found to fit this device" Compilation Err...

Does this allow you to compile your code?

Best regards,

James O'Neill - Applications Engineer - National Instruments

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this is a reply to

DanC12

Member

‎09-21-2016 10:59 AM

Hi marcg33b,

I'm unsure which link you are referring to. Can you repost the link and I will have a look.

[marcg33b]

Hi marcg33b,

I'm unsure which link you are referring to. Can you repost the link and I will have a look.

[J_Oneill]

Hi Everyone,

This was the content of the KB I posted 3 years ago:

Problem:
Sometimes an FPGA VI that can be compiled successfully in LV 2009 or previous version fails to compile in LV 2010 or later versions, saying that too many comps of "DSP48E" are found to fit this device.

This error is most likely to occur when the FPGA VI contains some High Throughput Multiply functions or some analysis functions that use High Throughput Multiply, such as FFT and DC and RMS Measurements.

How can I work around this error?

Solution:
In addition to the workaround listed in CAR #276311, one fix that users of LabVIEW 2012 can try is to add the following token to Labview.ini.

"niFpga_HT_Multiply_DisableCoreGen = true"

This token enables the Xilinx compiler to use resources other than DSP48E slices to implement multipliers.

Note: This token is only available in LabVIEW 2012, and setting this ini token may cause timing performance degradation.

Hope this helps,

James

[gerardpc]

Hi J_Oneill, should I add this token with or without the " "? I added it at the bottom of my Labview.ini file but didn't notice any changes in compilation. 

[linu95k]

Hi, I am facing a similar problem and I have read through this thread but unfortunately I am unable to access the CAR or http://ae.natinst.com/ link that people have been posting so I do not understand the reference made. can you please post links that are publicly accessible?

[rolfk]

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@linu95k wrote:

Hi, I am facing a similar problem and I have read through this thread but unfortunately I am unable to access the CAR or http://ae.natinst.com/ link that people have been posting so I do not understand the reference made. can you please post links that are publicly accessible?

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The ae.natinst.com server is never available to people outside of the National Instruments internal network.

Unfortunately, the alternative links that are publically available and posted in the posts thereafter seem to not have been ported over to the new document site management system.

You'll have to contact National Instruments technical support to get the contents of that document and/or read through the entire thread to get some ideas about what that document contained.