Assigning Global and Regional Resources

[Altera_Forum]

Hi, 

 I have a question on some related topic.  I want to assign global and regional clocks from/to my dedicated clock pins and PLLs.  I am able to allot a global resource from my pin to PLL, PLL_C1-Destination pin. I was able to route until yhe destination pin because I dont need and global line from C1 to the destination pin#1. But do not know how to do the same from the PLL C0 output to some internal signal and this one needs a global line.  I used the following command for assigning global line from pin to PLL set_instance_assignment -name GLOBAL_SIGNAL "GLOBAL CLOCK" -to "clocks:clocks|epll6_bb_a:a2d_clk_pll|altpll:altpl l_component|_clk1"  What does '_clk1' specify in this.  Regards, TM

[Altera_Forum]

The PLL outputs feed into the global routing resources, and the QuartusII fitter will automatically place PLL outputs onto global nets. So unless you want to control the type of global (device-wide global clock or regional clock) you don't have to make the global assignment to the PLL generated clocks.  

 When using external clock inputs as reference clocks the fitter should automatically utilize fixed paths from dedicated CLK inputs. Each Enhanced PLL in StratixII, for instance, can be fed by one of four dedicated clock inputs on the side of the packaged device adjacent to that PLL. Initially the fitter is best left to select the proper pin; if you do constrain the clock input to a specific pin make sure it is a legal source for the PLL.  Regarding names, "_clk1" designates one of the output clocks of the PLL. If you set up a PLL to generate three clocks, for instance, that PLL will have outputs "clk0", "clk1", and "clk2".   The QuartusII report file contains useful information on how your globals were handled. Open the report file (CNTL-R is the shortcut) and look under "Fitter / Resource Section / Global & Other Fast Signals". You should see a list of signals which were routed using the global resources plus a detailed table of how the signal was handled. You can right-click on any of the signals listed and from the popup menu select "Locate" and hyperlink to that signal in other QuartusII modules if you need to dig deeper.  Hope this helps.