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globalNetConnect fails due to pin and net polarity

mizzihood

Hello!

 I'm trying to connect vdd and vss nets to instance pins and the command
> globalNetConnect vdd_net -type pgpin   -pin VDD_pin -inst instance_name -verbose 
executes as expected and creates the connection. However, the command for vss connection
> globalNetConnect vss_net -type pgpin   -pin VSS_pin -inst instance_name -verbose 
returns the following message:
**ERROR: (ECNDB-1220): A global net connection rule for connection 'VSS_pin' of cell '...' to a global net '...' was specified. But the connection can not be made because the pin and the global net are not of the same polarity. Check the rule, and correct the issue. 

I have examined the lef file of the instance to whose pin I want to connect the vss and the declaration of the pin (apart from USE GROUND vs. USE POWER) is exactly the same, both are 'INOUT'. I would love some suggestions on where to look for the polarity and how to resolve the problem. 

 The nets are analog power supplies comming from pins, through a clamp. 

  • Hi,

     

    Not sure if you managed to solve this by now - but this error typically sigals that you are connecting a net of type power to a ground net, or vice versa.

    If the LEF of your cells is correct (has USE POWER and USE GROUND on the right pins), then you should look at how your vss_net is created. Is it specified as a ground net ? In Encounter 11.x you should have something like

    set init_pwr_net "vdd_net"
    set init_gnd_net "vss_net"

    or in Encounter 10.x

    set rda_Input(ui_pwrnet) {vdd_net}
    set rda_Input(ui_gndnet) {vss_net}

     in your TCL script.

     

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