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Explorer
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Registered: ‎06-28-2008

failed to create slice shape for instance--xpm_cdc_single

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vivado2017. 4, I just use a xpm_cdc_single macro in virtex7 690t. The implementation result showed a critical warning. " failed to create Slice shape for instance...reg[0]", found overlapping instances within the shape... reg[1],...reg[2]. How to solve the problem?
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Xilinx Employee
Xilinx Employee
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Registered: ‎05-08-2012

Re: failed to create slice shape for instance--xpm_cdc_single

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Hi @jlqsczw_2007 .

Are the ASYNC_REG and IOB set on the same FF cell? This would cause the ASYNC_REG to be ignored as the IOB constraint has precedence, and could cause the warning. Removing one of the constraints would show if this is the case.

If this doesn't help, I would suggest posting a schematic of the register in question, and the other two FFs mentioned in the error so the connectivity can be shown?


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Xilinx Employee
Xilinx Employee
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Registered: ‎06-27-2018

Re: failed to create slice shape for instance--xpm_cdc_single

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Hi @jlqsczw_2007,

Can you check this in latest version once? For how many instances/reg are you gettings this critical warning ? Check the properties of the registers which are triggering this warning, check if "ASYNC_REG" and "IOB" property is set on any of the registers. 

~Chinmay 

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Registered: ‎06-28-2008

Re: failed to create slice shape for instance--xpm_cdc_single

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Thanks.

Yes, I do add an IOB constraint for the port----my_din,

but I don't think it would cause the warning.

 

Here my code is as below----

 

xpm_cdc_single #(
.DEST_SYNC_FF(4), // DECIMAL; range: 2-10
.INIT_SYNC_FF(0), // DECIMAL; 0=disable simulation init values, 1=enable simulation init values
.SIM_ASSERT_CHK(0), // DECIMAL; 0=disable simulation messages, 1=enable simulation messages
.SRC_INPUT_REG(0) // DECIMAL; 0=do not register input, 1=register input
)
xpm_cdc_single_inst (
.dest_out(my_din_d4), // 1-bit output: src_in synchronized to the destination clock domain. This output is
// registered.

.dest_clk(dest_clk), // 1-bit input: Clock signal for the destination clock domain.
.src_clk(0), // 1-bit input: optional; required when SRC_INPUT_REG = 1
.src_in(my_din) // 1-bit input: Input signal to be synchronized to dest_clk domain.
);

 

(*ASYNC_REG = "TRUE"*)

FDRE #(
.INIT(1'b0) // Initial value of register (1'b0 or 1'b1)
) FDRE_inst (
.Q( my_din_invert), // 1-bit Data output
.C(dest_clk), // 1-bit Clock input
.CE(CE), // 1-bit Clock enable input
.R(R), // 1-bit Synchronous reset input
.D( ! my_din_d4) // 1-bit Data input
);

The critical warning only reported the registers in the xpm_cdc_single itself.

As you said, maybe the FDRE with ASYNC_REG = "TRUE" after the xpm_cdc_single cause the critical warning ?

How could I  remove the warning?

I really need my_din_d4 and my_din_invert to be placed in one SLICE for consistent latency.

 

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Xilinx Employee
Xilinx Employee
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Registered: ‎05-08-2012

Re: failed to create slice shape for instance--xpm_cdc_single

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Hi @jlqsczw_2007 .

Are the ASYNC_REG and IOB set on the same FF cell? This would cause the ASYNC_REG to be ignored as the IOB constraint has precedence, and could cause the warning. Removing one of the constraints would show if this is the case.

If this doesn't help, I would suggest posting a schematic of the register in question, and the other two FFs mentioned in the error so the connectivity can be shown?


-------------------------------------------------------------------------
Don’t forget to reply, kudo, and accept as solution.
-------------------------------------------------------------------------

 

---------------------------------------------------------------------------------------------
Don’t forget to reply, kudo, and accept as solution.
---------------------------------------------------------------------------------------------

View solution in original post

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Xilinx Employee
Xilinx Employee
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Registered: ‎06-27-2018

Re: failed to create slice shape for instance--xpm_cdc_single

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Is this the full code ? I was not able to reproduce the issue at my ene.

~Chinmay

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Explorer
Explorer
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Registered: ‎06-28-2008

Re: failed to create slice shape for instance--xpm_cdc_single

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I deleted the IOB constraint and the FDRE.

Then the warning disappeared.

You are right.

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