Why does Synopsys DC put "SYNOPSYS_UNCONNECTED" in the gate-level netlist?

[dcreddy1980]

Could any one know why synopsys DC puts "SYNOPSYS_UNCONNECTED" in the gate-level netlist. I am using synopsys-DC 2004.12 version.

Thanks in advance!

 

[gliss]

remove_unconnected_ports

Probably because it has optimized it out of the design. Check your HDL or put a no_touch option.

 

[xv_ning999]

synopsys unconnected

Can it cause any problem for backend using of the netlist?

 

[matthew_wang]

snopsys_unconnected

After synthesis, Synopsys assigns unconnected RTL ports as
SYNOPSYS_UNCONNECTED. These show up as one-pin nets.

 

[dcreddy1980]

synopsys_unconnected + synthesis

Probably because it has optimized it out of the design. Check your HDL or put a no_touch option.

Ya, u r right it is due to the optimization of the tool, i see this SYNOPSYS_UNCONNECTED....but could clearly tell me what option should be used to eliminate this net naming.

Thanks in advance!

 

[gliss]

synopsys unconnected _11,

whoops, that should be "dont_touch" not no_touch

 

[Atre]

synopsis unconnected

Probably because it has optimized it out of the design. Check your HDL or put a no_touch option.

Ya, u r right it is due to the optimization of the tool, i see this SYNOPSYS_UNCONNECTED....but could clearly tell me what option should be used to eliminate this net naming.

Thanks in advance!

You can instruct DC how to name the unconnected nets (ie. net_unconn).
Now, if you want to "eliminate" them from your design and you are sure it is safe to remove them, then you can use (several times):

remove_unconnected_ports -blast_buses [get_cells -hier *]

(I hope I typed write - see man for the command).

 

[visualart]

synopsys_unconnected sysnopsys

The unconnected maybe be added to the floating port when the DC optimize with the resouce of the design ware. Some of the primitive in the DW can't merge JUST with your design, some ports are unconnect, the DC name the port with the SYNOPSYS_UNCONNECTED.

 

[eixeix]

remove unconnected ports blast bits

please check manual for the following two variables control the netlist output:

verilogout_show_unconnected_pins
verilogout_unconnected_prefix

 

[praveen_venigalla]

Re: SYNOPSYS_UNCONNECTED

Dc Will Write down in netlist..SYNOPSYS_UNCONNECTED if during optimisation it cannot find a net its destination.

 

[rameshsuthapalli]

SYNOPSYS_UNCONNECTED

Hi All,

the SYNOPSYS_UNCONNECTED ports will not cause the problem in the P&R so u dont worry about it. if you want to remove the unconnected ports u can use "remove_unconnected_ports" or u can find some varible for removing the unconneted ports in the command.log.

regards,
Ramesh