cancel
Showing results for 
Show  only  | Search instead for 
Did you mean: 
Adventurer
Adventurer
7,153 Views
Registered: ‎11-02-2015

what is the first data of BRAM simulation result

Hi all,

 

I use vivado 2015.4 to simulate the BRAM and I meet a problem. Please see the picture below,

Capture.JPG

the first data should be ffff0000 and the first data in the picture 000000 should be replaced XXXXXXX.

 

Why does it happen? the first data is 000000 and how to fix the problem? Thanks

 

li

0 Kudos
Reply
14 Replies
Xilinx Employee
Xilinx Employee
7,093 Views
Registered: ‎08-02-2007

hi,

 

can you share the test-bench? Is this BRAM created out of an IP or is it a inferred BRAM?

 

--hs

----------------------------------------------------------------------------------------------
Kindly note- Please mark the Answer as "Accept as solution" if information provided is helpful.

Give Kudos to a post which you think is helpful and reply oriented.
----------------------------------------------------------------------------------------------
0 Kudos
Reply
Moderator
Moderator
7,023 Views
Registered: ‎07-21-2014

@pligroup

 

 

Are you using any very old primitive with Vivado? Also, are you using RTL to infer BRAM or using IP Catalog? 

 

Thanks,
Anusheel
-----------------------------------------------------------------------------------------------
Search for documents/answer records related to your device and tool before posting query on forums.
Search related forums and make sure your query is not repeated.

Please mark the post as an answer "Accept as solution" in case it helps to resolve your query.
Helpful answer -> Give Kudos
-----------------------------------------------------------------------------------------------

0 Kudos
Reply
Adventurer
Adventurer
6,984 Views
Registered: ‎11-02-2015

Yes, I use coe file to initialize the BRAM. I attach the testbench and coe file. The BRAM is created from IP catalog. 

 

thanks

 

0 Kudos
Reply
Adventurer
Adventurer
6,983 Views
Registered: ‎11-02-2015

@anusheel

 

I use vivado 2015.4. I use the IP catalog to infer the BRAM.

 

thanks

0 Kudos
Reply
Adventurer
Adventurer
6,974 Views
Registered: ‎11-02-2015

@anusheel  @htsvn

 

I also find a strange thing. I add a signal called flag. When I start the BRAM, flag will become 1 at the first clock and then it will become 0. please see the picture below,

Capture1.JPG

 

I use this to delete the 000000, but there is strange thing, when I zoom in the picture,

Capture2.JPG

There still exists 00000 and the data is even changed not at the rising edge of clock.

 

Please give me some suggestion to fix the problem, 

 

thanks

0 Kudos
Reply
Xilinx Employee
Xilinx Employee
6,948 Views
Registered: ‎09-20-2012

Hi @pligroup

 

Please attach block memory generator IP XCI file here.

Thanks,
Deepika.
--------------------------------------------------------------------------------------------
Google your question before posting. If someone's post answers your question, mark the post as answer with "Accept as solution". If you see a particularly good and informative post, consider giving it Kudos (the star on the left)
0 Kudos
Reply
Adventurer
Adventurer
6,906 Views
Registered: ‎11-02-2015

Hi @vemulad

 

Please see the attachment. Thanks.

0 Kudos
Reply
Xilinx Employee
Xilinx Employee
6,868 Views
Registered: ‎09-20-2012

Hi @pligroup

 

There is no signal by name flag inside the IP. 

 

I tried creating a project with the files shared but I cannot run simulation due to this missing file BRAM_test. Can you share this file too?

Thanks,
Deepika.
--------------------------------------------------------------------------------------------
Google your question before posting. If someone's post answers your question, mark the post as answer with "Accept as solution". If you see a particularly good and informative post, consider giving it Kudos (the star on the left)
0 Kudos
Reply
Xilinx Employee
Xilinx Employee
6,865 Views
Registered: ‎09-20-2012

Hi @pligroup

 

Regarding the read to address zero, I was able to reproduce this issue in 2015.4. However when I migrated the project to 2016.2 I did not face this problem. Below is simulation result from vivado 2016.2. Can you try upgrading to 2016.2?

 

Capture.PNG

Thanks,
Deepika.
--------------------------------------------------------------------------------------------
Google your question before posting. If someone's post answers your question, mark the post as answer with "Accept as solution". If you see a particularly good and informative post, consider giving it Kudos (the star on the left)
0 Kudos
Reply
Adventurer
Adventurer
6,495 Views
Registered: ‎11-02-2015

Hi, @vemulad

 

I have third questions. 

 

first, I am a student, so can I directly upgrade the vivado to 2016.2 without license?

 

second, I attached my testbench and BRAM file, can you help me run this code at vivado 2016.2?

 

third, if the simulation result is not the same at vivado 2015.4 and Vivado 2016.2, will it be difference if I implement the code?

 

Thanks,

pengli

 

 

0 Kudos
Reply
Xilinx Employee
Xilinx Employee
6,464 Views
Registered: ‎09-20-2012

Hi @pligroup

 

This is 2015.4 XSIM simulator issue.

 

You can use Questasim or modelsim with Vivado 2015.4 to get correct results.

Thanks,
Deepika.
--------------------------------------------------------------------------------------------
Google your question before posting. If someone's post answers your question, mark the post as answer with "Accept as solution". If you see a particularly good and informative post, consider giving it Kudos (the star on the left)
0 Kudos
Reply
Adventurer
Adventurer
6,439 Views
Registered: ‎11-02-2015

Hi @vemulad

 

Thank you for your help. So if I get the correct result at modelsim, then I download the bit stream into ZYNQ board with Vivado 2015.4, can I get the correct result? Besides, look at your picture, the first data is also ffff0000.

 

thanks

0 Kudos
Reply
Xilinx Employee
Xilinx Employee
6,240 Views
Registered: ‎09-20-2012

Hi @pligroup

 

Yes, this should work fine in hardware.

Thanks,
Deepika.
--------------------------------------------------------------------------------------------
Google your question before posting. If someone's post answers your question, mark the post as answer with "Accept as solution". If you see a particularly good and informative post, consider giving it Kudos (the star on the left)
0 Kudos
Reply
Xilinx Employee
Xilinx Employee
6,169 Views
Registered: ‎09-20-2012

Hi @pligroup

 

If your issue is resolved, please close this thread by marking the answer.

Thanks,
Deepika.
--------------------------------------------------------------------------------------------
Google your question before posting. If someone's post answers your question, mark the post as answer with "Accept as solution". If you see a particularly good and informative post, consider giving it Kudos (the star on the left)
0 Kudos
Reply