need to access the first registers to I/O pads using db commands

 Hey Arun,

  When you talk 2nd level are you talking about hierarchy or logic depth?

Hi Arun,

If you're talking about logic depth, there's a script in the gifts directory that might be helpful:

<install_path>/share/fe/gift/scripts/tcl/userAddMenuPullInstsToIos.tcl

The script provides a way to "trace and pull" instances connected IOs (or pins on IO cells) close to the IO they're connected to.  It is similar conceptually to the native "placeJtag" functionality, but is more brute force in the way it works.

If you're talking about 2nd level of hierarchy, please do reply and let us know as that is a different challenge altogether.

-Bob

yes, 2nd level means logic depth.. if a register is not accessed in the trace path from i/o pad

then my pointer has to keep on accessing until a register is found..

This fashion has to be continued for every terminal of I/O pad and every net the terminals are

connected to..

Thanks

Arun

Hi Bob

Thanks for your reply..

My intention here is to access the registers which are found first in the trace path from any

I/O pad.. I'm able to access the first instance which is connected to one of the terminals of  I/O pad.But that instance is not a register..So i need to access the instances until a register is found..

Later in the same way i need to access for the other terminals and nets connected to the same I/O  pad...

Let me show you my script which I've been working on..

proc input_inst_ptr {inst_ptr} {

         dbForEachInstOutputTerm $inst_ptr termPtr {
                                set termName [dbTermName $termPtr]
                                set netPtr [dbTermNet $termPtr]
                                set netName [dbNetName $netPtr]

                     dbForEachNetInputTerm $netPtr outputTermPtr {
                                if { [dbIsObjTerm $outputTermPtr] == 1}  {
                                    set instName [dbTermInstName $outputTermPtr]
                                    set instPtr [dbGetInstByName $instName]
                                    set cellName [dbInstCellName $instPtr]
                                    set cellPtr [dbInstCell $instPtr]

                                     if {[dbIsCellSequential $cellPtr]} {
                                        puts   "Input Reg Name :$instName"
                                        puts "Input Reg Name :$instName"

                                   }   else {

                                     input_inst_ptr $instPtr

                                         }
                                                                          }

                                                              }

                                             }

             }
 

Here the procedure takes an instance pointer  (ex: I/O instance for the first time and

later other instances) as its argument and traces the paths for its

corresponding terminals until a register is found in that path...

Awaiting your reply

-Arun

I think your script is looping because it's calling itself from within the foreach loop.  When I wrote similar I had a lot of issues with infinite loops to and it was a tough to troubleshoot for sure.  You can see how I went about it in userAddMenuPullInstsToIos.tcl in the "userTraceIoTerm" and "userInstInsts" procs.  It was pretty ugly!

You know, when I wrote that script it was a few years ago- before CTE-TCL commands existed in Encounter.  I think those commands might be much better suited to your need than performing the traversal manually yourself.  Being timing-engine related commands, the CTE-TCL commands have the ability to traverse through logic cones.  Like this:

all_fanout
              -from {<collection> | <object_list>}
              [-levels <value>]
              [-pin_levels <value>]
              [-endpoints_only]
              [-only_cells]
              [> <file_name>] 

For instance, in your case you could do:

all_fanout -from [get_pins i0/Y] -levels 2 -endpoints_only -only_cells

What do you think?

For more information on CTE-TCL commands, see the Advanced Timing Tcl Scripting chapter of the Encounter User's Guide.