Thursday, July 14, 2011

Xilinx Integration: No ModelSim GUI appears when simulation called from ISE Project Navagator


Need to change a TCL script. On the machine its

C:\Tools\Xilinx\13.2\ISE_DS\ISE\data\projnav\scripts\dpm_modelsimTasks.tcl

on line 77 there is this if statement

          if { [dpm_flowsTestBatchEnv] } {

            set sBatchSwitch "-c"

          } else {

            set sBatchSwitch ""

          }

Add the -gui switch to the else condition so the statement reads

          if { [dpm_flowsTestBatchEnv] } {

            set sBatchSwitch "-c"

          } else {

            set sBatchSwitch "-gui"

         }

Thursday, July 7, 2011

What is an X in digital design?

An X implies that a signal value is unknown (cannot be positively determined) and can be either one or zero. Unknown signal states are common while debugging simulation results and typically signify uninitialized signals or signals driven by more than one driver. In post layout simulations, they can also indicate a timing violation.

On the board / In reality there is nothing implies to 'X' but what it implies is that the result is not known/ cannot be predicted. The situation which we do not like to be in