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7,211 Views
Registered: ‎10-21-2010

False error in map, with BUFR in MMCM feedback path

 

I am using a MMCME2_ADV in a zynq 7020 device, with CLKFBOUT looped back into CLKFBIN through a BUFR, Compensation is set to ZHOLD. I am doing my builds through EDK/XPS. In map, I get the following error:

 

ERROR:PhysDesignRules:2257 - Unsupported MMCME2_ADV connectivity. The signal
ircamera_deserializer/ircamera_deserializer/calibration/mmcm_fbin on the CLKFBIN pin of MMCME2_ADV comp
ircamera_deserializer/ircamera_deserializer/calibration/clock_generator with COMPENSATION mode ZHOLD must be driven by the CLKFBOUT pin on the same MMCME2_ADV through a BUFG, BUFH or BUFR.

 

It seems to me like the situation map is complaining about does not occur in reality. What am I doing wrong? How do I remove the error?

 

Thanks,

Lucian

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7 Replies
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Xilinx Employee
Xilinx Employee
7,169 Views
Registered: ‎04-16-2012

Re: False error in map, with BUFR in MMCM feedback path

Hello Lucian,

Which tool (ISE or Vivado) and version are you using?
It seems like tool is not propagating the COMPENSATION attribute as ZHOLD even though it was specifically set to ZHOLD.

If you are using Vivado, can you write an xdc constraint and force the COMPENSATION to ZHOLD.


Thanks,
Vinay
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Moderator
Moderator
7,161 Views
Registered: ‎01-16-2013

Re: False error in map, with BUFR in MMCM feedback path

Hi,

There is one limitation.
MMCM and BUFR should be in same clock region.

Thanks,
Yash
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7,161 Views
Registered: ‎10-21-2010

Re: False error in map, with BUFR in MMCM feedback path

Hi Vinay,

 

I am using ISE 14.7. Upgrading to Vivado is not an option for me at this time unfortunately.

 

Is there a way to force the compensation in UCF for ISE? Could you give an example?

 

Thanks,

Lucian

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7,141 Views
Registered: ‎10-21-2010

Re: False error in map, with BUFR in MMCM feedback path

 Just clarifying, after @yashp commented, that I already have constraints in place to keep all logic within a single clock region.

 

Thanks,

Lucian

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Xilinx Employee
Xilinx Employee
7,131 Views
Registered: ‎04-16-2012

Re: False error in map, with BUFR in MMCM feedback path

Hello @lucian.petrica 

 

Follow these steps:

 

1. Open Synthesized in PlanAhead. See snapshot below: (by double clicking on Floorplanning PlanAhead)

floorplann.PNG

2. Once the design is invoked in PlanAhead, select the MMCM and change its properties (compensation property) using properties window: See below snapshot:

chang_properties.PNG

 

Then click on Save button (top-left corner) and close the planAhead.

Next run implementation in ISE.

 

Thanks and regards,

Vinay

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7,113 Views
Registered: ‎10-21-2010

Re: False error in map, with BUFR in MMCM feedback path

Hi Vinay,

 

I did open my synthesized design in planahead and checked the MMCM attributes, but the compensation is already set to ZHOLD (see attached image). I also tried adding the following line in my UCF:

 

INST "ircamera_deserializer/ircamera_deserializer/calibration/clock_generator" COMPENSATION = ZHOLD;

 

So it seems like the compensation attribute is being correctly set, but somehow the design still fails DRC.

 

I've added a schematic of the design in the hope of giving you some more ideas :) The clocking scheme is as follows:

 

LVDS clocks -> IBUFGDS -> ISERDESE2 (D to O) -> MMCM_ADV -> BUFR (clkfbout to clkfbin)

 

From the CLKOUT0 pin of the MMCM i drive a BUFR and BUFIO for a deserialization application. 

 

Thanks,

Lucian

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Xilinx Employee
Xilinx Employee
6,950 Views
Registered: ‎04-16-2012

Re: False error in map, with BUFR in MMCM feedback path

Hello,

Did you try setting this COMPENSATION attribute in HDL file?

Thanks,
Vinay
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