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AR# 54964

Vivado NCsim Timing Simulation - SDF annotation does not complete for all instances and W,SDFNEP warnings are received

Description

I am attempting to run timing simulation using NCsim but receive the following warnings:

ncelab: *W,SDFNEP: Unable to annotate to non-existent path (IOPATH (posedge RST) LOCKED) of instance guido_tb_top.DUT.clk_wiz_v4_3_0_i.inst.plle2_adv_inst of module PLLE2_ADV <./guido_vivado_netlist.sdf, line 537>.
ncelab: *W,SDFNEP: Unable to annotate to non-existent path (IOPATH (posedge PRE) Q) of instance guido_tb_top.DUT.sip_slave_top_i.edge_detected_reg of module FDPE <./guido_vivado_netlist.sdf, line 575>.
ncelab: *W,SDFNEP: Unable to annotate to non-existent path (IOPATH (posedge CLR) Q) of instance guido_tb_top.DUT.sip_slave_top_i.incr_read_reg of module FDCE <./guido_vivado_netlist.sdf, line 593>.
ncelab: *W,SDFNEP: Unable to annotate to non-existent path (IOPATH (posedge PRE) Q) of instance guido_tb_top.DUT.sip_slave_top_i.\scl_dly_reg[0]  of module FDPE <./guido_vivado_netlist.sdf, line 677>.
ncelab: *W,SDFNEP: Unable to annotate to non-existent path (IOPATH (posedge PRE) Q) of instance guido_tb_top.DUT.sip_slave_top_i.\scl_dly_reg[1]  of module FDPE <./guido_vivado_netlist.sdf, line 695>.
ncelab: *W,SDFNEP: Unable to annotate to non-existent path (IOPATH (posedge PRE) Q) of instance guido_tb_top.DUT.sip_slave_top_i.\scl_dly_reg[2]  of module FDPE <./guido_vivado_netlist.sdf, line 713>.
ncelab: *W,SDFNEP: Unable to annotate to non-existent path (IOPATH (posedge PRE) Q) of instance guido_tb_top.DUT.sip_slave_top_i.scl_med3_reg of module FDPE <./guido_vivado_netlist.sdf, line 731>.
ncelab: *W,SDFNEP: Unable to annotate to non-existent path (IOPATH (posedge PRE) Q) of instance guido_tb_top.DUT.sip_slave_top_i.\sda_dly_reg[3]  of module FDPE <./guido_vivado_netlist.sdf, line 798>.
ncelab: *W,SDFNEP: Unable to annotate to non-existent path (IOPATH (posedge PRE) Q) of instance guido_tb_top.DUT.sip_slave_top_i.sda_dly_reg_p of module FDPE <./guido_vivado_netlist.sdf, line 827>.
ncelab: *W,SDFNEP: Unable to annotate to non-existent path (IOPATH (posedge PRE) Q) of instance guido_tb_top.DUT.sip_slave_top_i.sda_dly_reg_p_0 of module FDPE <./guido_vivado_netlist.sdf, line 845>.
ncelab: *W,SDFNEP: Unable to annotate to non-existent path (IOPATH (posedge PRE) Q) of instance guido_tb_top.DUT.sip_slave_top_i.sda_dly_reg_p_1 of module FDPE <./guido_vivado_netlist.sdf, line 863>.
ncelab: *W,SDFNEP: Unable to annotate to non-existent path (IOPATH (posedge CLR) Q) of instance guido_tb_top.DUT.sip_slave_top_i.sda_e_reg of module FDCE <./guido_vivado_netlist.sdf, line 881>.

 

Solution

Vivado is writing out SDF files that have edge sensitive IOPATH for primitives like FDCE and FDPE.

For example,

(IOPATH (posedge CLR) Q (303.0:380.0:380.0)) 

However, the example "simprim" specify line looks like the following:

(CLR => Q) = (0:0:0, 0:0:0); 

This causes the annotation failure in NCsim timing simulation. 

To eliminate the warnings, you can manually edit the IOPATH line in SDF to remove the positive edge notation:

(IOPATH CLR Q (303.0:380.0:380.0)) 

 

Note: Vivado Simulator and ModelSim do not complain about the mismatch and can annotate the SDF correctly. 


The models have been updated in Vivado 2014.3 so that the specify syntax is properly accepted by NCsim.
 

(posedge CLR => (Q +: D)) = (0:0:0, 0:0:0); 

Linked Answer Records

Master Answer Records

Answer Number Answer Title Version Found Version Resolved
58890 Xilinx Simulation Solution Center - Design Assistant - Third Party Simulators - Cadence IES N/A N/A
AR# 54964
Date Created 03/18/2013
Last Updated 04/15/2015
Status Active
Type General Article
Tools
  • Vivado Design Suite - 2012.1
  • Vivado Design Suite - 2012.2
  • Vivado Design Suite - 2012.3
  • More
  • Vivado Design Suite - 2012.4
  • Vivado Design Suite - 2013.1
  • Vivado Design Suite - 2013.2
  • Vivado Design Suite - 2013.3
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