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guetguet
Visitor
Visitor
13,532 Views
Registered: ‎07-04-2012

Signal unconnected in a block

Hello everyone !

I have a serious problem for 2 hours ... I think the solution must be easy but I don't know what to do. So the XST tool shows me a lot of warning. Several of them is due to a signal which is not connected according the XST Tool. But in my implementation, the signals which are unconnected according the XST tool are connected. Thus I don't understand why the XST detects those signals as not connected. Bellow is a part of the warnings :

 

WARNING:Xst:2677 - Node <cycle> of sequential type is unconnected in block <SweepJammingDDSInst>.
WARNING:Xst:2677 - Node <stepX2S1_31> of sequential type is unconnected in block <SweepJammingDDSInst>.
WARNING:Xst:2677 - Node <invROM1Douta> of sequential type is unconnected in block <SweepJammingDDSInst>.
WARNING:Xst:2677 - Node <invROM1Doutb> of sequential type is unconnected in block <SweepJammingDDSInst>.
WARNING:Xst:2677 - Node <invROM2Doutb> of sequential type is unconnected in block <SweepJammingDDSInst>.
WARNING:Xst:2677 - Node <VphaseAccumulator3_31> of sequential type is unconnected in block <SweepJammingDDSInst>.
WARNING:Xst:2677 - Node <invROM1DoutaS1> of sequential type is unconnected in block <SweepJammingDDSInst>.
WARNING:Xst:2677 - Node <invROM1DoutbS1> of sequential type is unconnected in block <SweepJammingDDSInst>.
WARNING:Xst:2677 - Node <invROM2DoutbS1> of sequential type is unconnected in block <SweepJammingDDSInst>.
WARNING:Xst:2677 - Node <invROM2Douta> of sequential type is unconnected in block <SweepJammingDDSInst>.
WARNING:Xst:2677 - Node <invROM1DoutaS2> of sequential type is unconnected in block <SweepJammingDDSInst>.
WARNING:Xst:2677 - Node <invROM1DoutbS2> of sequential type is unconnected in block <SweepJammingDDSInst>.
WARNING:Xst:2677 - Node <invROM2DoutbS2> of sequential type is unconnected in block <SweepJammingDDSInst>.
WARNING:Xst:2677 - Node <invROM2DoutaS1> of sequential type is unconnected in block <SweepJammingDDSInst>.
WARNING:Xst:2677 - Node <Douta_ROM1S2_0> of sequential type is unconnected in block <SweepJammingDDSInst>.
WARNING:Xst:2677 - Node <Douta_ROM1S2_1> of sequential type is unconnected in block <SweepJammingDDSInst>.
WARNING:Xst:2677 - Node <Douta_ROM1S2_2> of sequential type is unconnected in block <SweepJammingDDSInst>.
WARNING:Xst:2677 - Node <Douta_ROM1S2_3> of sequential type is unconnected in block <SweepJammingDDSInst>.
WARNING:Xst:2677 - Node <Douta_ROM1S2_4> of sequential type is unconnected in block <SweepJammingDDSInst>.
WARNING:Xst:2677 - Node <Douta_ROM1S2_5> of sequential type is unconnected in block <SweepJammingDDSInst>.
WARNING:Xst:2677 - Node <Douta_ROM1S2_6> of sequential type is unconnected in block <SweepJammingDDSInst>.
WARNING:Xst:2677 - Node <Douta_ROM1S2_7> of sequential type is unconnected in block <SweepJammingDDSInst>.
WARNING:Xst:2677 - Node <Douta_ROM1S2_8> of sequential type is unconnected in block <SweepJammingDDSInst>.
WARNING:Xst:2677 - Node <Douta_ROM1S2_9> of sequential type is unconnected in block <SweepJammingDDSInst>.
WARNING:Xst:2677 - Node <Douta_ROM1S2_10> of sequential type is unconnected in block <SweepJammingDDSInst>.
WARNING:Xst:2677 - Node <Douta_ROM1S2_11> of sequential type is unconnected in block <SweepJammingDDSInst>.

 

Please find as an attachment the file which contains my architecture and its entity.

 

Thanks !

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3 Replies
eteam00
Instructor
Instructor
13,524 Views
Registered: ‎07-21-2009

The clue may be in some of the other 'logic trimmed' warning messages.  Trace the trimmed signal to its source, and see if its source is also trimmed.  This is tedious work, but sometimes necessary.

 

-- Bob Elkind

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gszakacs
Professor
Professor
13,522 Views
Registered: ‎08-14-2007

It's likely that the problem is not in the module you posted, but in its connections at the higher

level.  Make sure that the module's reset and clock inputs are properly driven, and the the

module's outputs are actually used (not "trimmed").

 

-- Gabor

-- Gabor
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sauravs
Xilinx Employee
Xilinx Employee
13,431 Views
Registered: ‎08-14-2012

This warning indicates that the sequential signal in the block is unconnected and will be removed. This is a common warning during Synthesis optimization. It does not always indicate a coding error. If thePost-Synthesis/Translate simulation shows the design functions correctly, you can safely ignore this warning. 

If this signal is not expected to be unconnected or removed, check if thedownstream loads of this signal are correctly connected. To preventthis signalfrombeing removed, add KEEP and S (Save Net Flag) constraints to it. For the syntax of the constraints, please refer to Constraints Guide.

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