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Explorer
Explorer
10,522 Views
Registered: ‎07-10-2008

Issue for Spartan 6 configuration Mode

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We have the same spartan 6 application design for two projects seperated by 3 years.

 

We are experiencing the issue for spartan 6 configuration mode.

 

We pull down configuration mode Pin M1 with 10k resistor but this setup is not working for most recent design.

 

We have to use 2k resistor to repalce 10k resistor to make Spartan 6 be programmed by flash.

 

Please let me know what is the potential problem for above issue?

 

Do you think if it is possible the FPGA is not baked long enough before assembling?

 

Many thanks.

 

David.

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Teacher eteam00
Teacher
18,907 Views
Registered: ‎07-21-2009

Re: Issue for Spartan 6 configuration Mode

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Given that the maximum current for a Spartan-6 internal 'weak pullup' is 350uA - 500uA, a 10K pulldown R is too high a value to guarantee a LOW logic level.

 

-- Bob Elkind

SIGNATURE:
README for newbies is here: http://forums.xilinx.com/t5/New-Users-Forum/README-first-Help-for-new-users/td-p/219369

Summary:
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5. Students: Copying code is not the same as learning to design.
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4 Replies
Scholar austin
Scholar
10,515 Views
Registered: ‎02-27-2008

Re: Issue for Spartan 6 configuration Mode

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d,

 

I would check if you have contaminated water during the wash of the flux during assembly.

 

 

Austin Lesea
Principal Engineer
Xilinx San Jose
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Teacher eteam00
Teacher
18,908 Views
Registered: ‎07-21-2009

Re: Issue for Spartan 6 configuration Mode

Jump to solution

Given that the maximum current for a Spartan-6 internal 'weak pullup' is 350uA - 500uA, a 10K pulldown R is too high a value to guarantee a LOW logic level.

 

-- Bob Elkind

SIGNATURE:
README for newbies is here: http://forums.xilinx.com/t5/New-Users-Forum/README-first-Help-for-new-users/td-p/219369

Summary:
1. Read the manual or user guide. Have you read the manual? Can you find the manual?
2. Search the forums (and search the web) for similar topics.
3. Do not post the same question on multiple forums.
4. Do not post a new topic or question on someone else's thread, start a new thread!
5. Students: Copying code is not the same as learning to design.
6 "It does not work" is not a question which can be answered. Provide useful details (with webpage, datasheet links, please).
7. You are not charged extra fees for comments in your code.
8. I am not paid for forum posts. If I write a good post, then I have been good for nothing.
Scholar austin
Scholar
10,500 Views
Registered: ‎02-27-2008

Re: Issue for Spartan 6 configuration Mode

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Whoops!

 

Good catch.  I was not thinking of the pullups.

 

I was only thinking of leakage of pins (<10uA).


Clearly you have found the cause:  the pullups may be stronger, or weaker as part of normal process variation.  A marginal resistor value may for some lots of material stop working.

 

Thank you!

Austin Lesea
Principal Engineer
Xilinx San Jose
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Explorer
Explorer
10,485 Views
Registered: ‎07-10-2008

Re: Issue for Spartan 6 configuration Mode

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It is so good to know.

Many thanks.

Have a nice day.

David.
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