UPGRADE YOUR BROWSER

We have detected your current browser version is not the latest one. Xilinx.com uses the latest web technologies to bring you the best online experience possible. Please upgrade to a Xilinx.com supported browser:Chrome, Firefox, Internet Explorer 11, Safari. Thank you!

cancel
Showing results for 
Search instead for 
Did you mean: 
Visitor yuriom
Visitor
338 Views
Registered: ‎09-28-2018

Is there a reliable way to lock LUT6_2's to specific BEL's/sites?

Is there a reliable way to lock LUT6_2's to specific BEL's? I tried using various combinations of the LOC, BEL, and DONT_TOUCH properties without much success. I am targeting VCU-1525 with Vivado 2018.3.

0 Kudos
4 Replies
Xilinx Employee
Xilinx Employee
330 Views
Registered: ‎05-22-2018

Re: Is there a reliable way to lock LUT6_2's to specific BEL's/sites?

Hi @yuriom ,

You can achive that using GUI by selecting the "Fixed" property of LUT instance as shown below:

lut_belCapture.JPG

 

After this save the constraints, the below constraints will be added to XDC.

 

set_property BEL A6LUT [get_cells {arnd1/transformLoop[0].ct/xOutReg_reg_i_17}]
set_property LOC SLICE_X12Y163 [get_cells {arnd1/transformLoop[0].ct/xOutReg_reg_i_17}]

 

Thanks,

Raj

0 Kudos
Visitor yuriom
Visitor
319 Views
Registered: ‎09-28-2018

Re: Is there a reliable way to lock LUT6_2's to specific BEL's/sites?

Hi @rshekhaw  ,

I know I can do this with LUT[1-5]. My question is specifically about LUT6_2. It seems like Vivado treats each LUT6_2 as a combination of a LUT5 and a LUT6, and complains about the site being occupied already.

0 Kudos
Moderator
Moderator
308 Views
Registered: ‎11-04-2010

Re: Is there a reliable way to lock LUT6_2's to specific BEL's/sites?

Hi, @yuriom ,

You can refer to LUTNM in UG903 to pack the LUTs first:

A unique string name applied to two LUTs to control their placement on a single LUT
site. Unlike HLUTNM, LUTNM can be used to combine LUTs that belong to different
hierarchical cells.

 

-------------------------------------------------------------------------
Don't forget to reply, kudo, and accept as solution.
-------------------------------------------------------------------------
0 Kudos
Xilinx Employee
Xilinx Employee
297 Views
Registered: ‎05-14-2008

Re: Is there a reliable way to lock LUT6_2's to specific BEL's/sites?

Are you instantiating a LUT6_2 instance in your RTL code?

Or is it an inferred LUT6_2?

What is the LUT objects like in the netlist?

What constraints did you try and what error did you received?

-vivian

-------------------------------------------------------------------------------------------------
Don’t forget to reply, kudo, and accept as solution.
-------------------------------------------------------------------------------------------------
如果提供的信息能解决您的问题,请标记为“接受为解决方案”。
如果您认为帖子有帮助,请点击“奖励”。谢谢!
-------------------------------------------------------------------------------------------------
0 Kudos