Spartan6 Suspend-Pin unconnected

nico@work · ‎04-19-2012

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

nico@work · ‎04-19-2012

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

HELP!!!

eteam00 · ‎07-21-2009

What have you done so far to troubleshoot your board?

Would you like to post your board schematics for review?

-- Bob Elkind

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nico@work · ‎04-19-2012

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?

eteam00 · ‎07-21-2009

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

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gszakacs · ‎08-14-2007

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

nico@work · ‎04-19-2012

But Table 1-5 in UG394 say also that Suspend mode is not activated by default.
My hope is getting smaller! :-(

eteam00 · ‎07-21-2009

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

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2. Search the forums (and search the web) for similar topics.
3. Do not post the same question on multiple forums.
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5. Students: Copying code is not the same as learning to design.
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7. You are not charged extra fees for comments in your code.
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eteam00 · ‎07-21-2009

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

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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.
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7. You are not charged extra fees for comments in your code.
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