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Visitor nico@work
Visitor
7,185 Views
Registered: ‎04-19-2012

Spartan6 Suspend-Pin unconnected

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Hello @ all!

 

What happens if the suspend-pin on a spartan6 (XC6SLX45) is unconnected?

My spartan6 dont speak to the configuration-flash, no clock or data.

 

Thanks and greetings

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Visitor nico@work
Visitor
8,316 Views
Registered: ‎04-19-2012

Re: Spartan6 Suspend-Pin unconnected

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I have patched my 6-layer-board (mill the board from rear side till the ball of FPGA) and connect the suspend-pin to GND. But the FPGA don't configure.

 

So I have inspected everything over again and have found my mistake. One mode-pin was not connected properly!

Thanks all for help!

patch.png
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14 Replies
Visitor nico@work
Visitor
7,165 Views
Registered: ‎04-19-2012

Re: Spartan6 Suspend-Pin unconnected

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FPGA is in SPI-Master-Mode and connected to a 16MBit Flash. But it does not configure!

HELP!!!
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Teacher eteam00
Teacher
7,161 Views
Registered: ‎07-21-2009

Re: Spartan6 Suspend-Pin unconnected

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What have you done so far to troubleshoot your board?

Would you like to post your board schematics for review?

 

-- 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.
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Visitor nico@work
Visitor
7,157 Views
Registered: ‎04-19-2012

Re: Spartan6 Suspend-Pin unconnected

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I have checked all voltages, the connection between FPGA and Flash, the configurations-pins(init_b, prog_b) and the Mode-Pins. I have also checked the spi-signals(FPGA-Flash) at power-up, but these are not active.

 

My schematics is equal to the one in user guide(ug380, page 40). See attachment. Only the suspend-pin is not connected. :-(

 

It is possible that the missing GND at suspend-pin cause this?

sch.JPG
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Teacher eteam00
Teacher
7,151 Views
Registered: ‎07-21-2009

Re: Spartan6 Suspend-Pin unconnected

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It is possible that the missing GND at suspend-pin cause this?

 

Yes.

 

See UG380 Table 5-2, including the notes.

Also see UG394 (v1.0) page 20.

 

-- 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.
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Instructor
Instructor
7,146 Views
Registered: ‎08-14-2007

Re: Spartan6 Suspend-Pin unconnected

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This note appears in almost every section of the Spartan 6 Config User Guide:

 

 

So I think it's reasonable that leaving the pin unconnected could affect startup configuration.

Have you tried to configure the FPGA directly using Impact?

 

-- Gabor

-- Gabor
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Visitor nico@work
Visitor
7,131 Views
Registered: ‎04-19-2012

Re: Spartan6 Suspend-Pin unconnected

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But Table 1-5 in UG394 say also that Suspend mode is not activated by default.
My hope is getting smaller! :-(
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Teacher eteam00
Teacher
7,129 Views
Registered: ‎07-21-2009

Re: Spartan6 Suspend-Pin unconnected

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Nico,

 

There seems to be a few inconsistencies between the various Xilinx docs on how SUSPEND pin is enabled, disabled, pulled up, not pulled up, etc.  I would suggest that you pull SUSPEND pin LOW.  If you do not, then any other efforts to fix your board will have the SUSPEND issue yet unsettled, and causing doubts.

 

-- 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.
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Teacher eteam00
Teacher
7,125 Views
Registered: ‎07-21-2009

Re: Spartan6 Suspend-Pin unconnected

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Nico,

 

I have opened a webcase to answer your questions and improve the descriptions of SUSPEND in UG380 and UG394.  here is the text of the webcase support request:

 

Need definitive description of SUSPEND pin function at power-on and configuration.

UG380 says SUSPEND pin must be tied LOW for configuration (many places).

UG394 (v1.0) Table 1-5 and page 14 indicates that SUSPEND function is default DISABLED, and is enabled or disabled by a BITGEN setting, early in the config bitstream header.

Does SUSPEND = 1 at power-on prevent the beginning of configuration, and also prevent the reading of the BITGEN setting for enabling/disabling SUSPEND function?

Or does configuration *always* begin -- regardless of SUSPEND pin level -- until the SUSPEND_ENABLE mode bit is read from the config bitstream header?

Clarification of SUSPEND pin role in configuration process should be made clear and unambiguous in both UG380 and UG394.

 

-- 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.
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Visitor nico@work
Visitor
7,119 Views
Registered: ‎04-19-2012

Re: Spartan6 Suspend-Pin unconnected

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Thank you so much for your help! I am curious an the answer.
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Teacher eteam00
Teacher
5,894 Views
Registered: ‎07-21-2009

Re: Spartan6 Suspend-Pin unconnected

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Here is the initial webcase response:

 

As you mentioned, UG380 states that the SUSPEND pin must be tied LOW for configuration. If this requirement is not respected the memory cell array may not be initialized correctly. Random data in the configuration memory, causes contentions.  It is important to ensure the SUSPEND pin is low during power up and configuration.

  • If the SUSPEND pin is left floating and if the bitgen option is enabled, there is the possibility that the FPGA will enter into SUSPEND mode.
  • If the SUSPEND pin is left floating and if the bitgen option is disabled, I would expect that the FPGA will not enter SUSPEND mode as the SUSPEND pin will be ignored. You should not be able to accidentally enter into a Suspend mode if the pin floats, but you will have other power and noise implications on the pin.  

We have not characterised behaviour other than SUSPEND being tied LOW for power-on and configuration, as this is our recommendation, and so, we cannot guarantee the behaviour if SUSPEND = 1 at power-on.  Therefore, it is difficult to predict what will happen.

-- 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.
Visitor nico@work
Visitor
8,317 Views
Registered: ‎04-19-2012

Re: Spartan6 Suspend-Pin unconnected

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I have patched my 6-layer-board (mill the board from rear side till the ball of FPGA) and connect the suspend-pin to GND. But the FPGA don't configure.

 

So I have inspected everything over again and have found my mistake. One mode-pin was not connected properly!

Thanks all for help!

patch.png
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Teacher eteam00
Teacher
5,867 Views
Registered: ‎07-21-2009

Re: Spartan6 Suspend-Pin unconnected

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Congratulations on finding the error.

 

Nice photograph!

 

-- 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.
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Teacher rcingham
Teacher
5,862 Views
Registered: ‎09-09-2010

Re: Spartan6 Suspend-Pin unconnected

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I suggest that you glue all modification wires to the PCB to reduce the risk of them becoming detatched.

------------------------------------------
"If it don't work in simulation, it won't work on the board."
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Instructor
Instructor
5,860 Views
Registered: ‎08-14-2007

Re: Spartan6 Suspend-Pin unconnected

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Just a note for next time you need to debug this sort of problem:

 

Impact allows you to view the state of the configuration pins.  You should have been

able to see the state of the mode pins as seen by the internal logic just by using

one of the debug functions of Impact.  Especially with BGA's this is a valuable tool.

 

When I design a board with BGA's I typically require the layout designer to place a

via for each unconnected pad just in case I find I needed to make a connection.

It helps you to avoid the sort of rework you show in your nice picture.

 

-- Gabor

-- Gabor