Answers Database

How to specify a BUFGP vs. BUFGS using Viewsynthesis?


Record #973

Product Family:  Software

Product Line:  ViewLogic

Problem Title:
How to specify a BUFGP vs. BUFGS using Viewsynthesis?


Problem Description:
Viewsynthesis by default infers a BUFG on the clock inputs and doesn't let you
specify whether it is going to be a BUFGP or a BUFGS.

This solution applies to Viewsynthesis 5.02x and Workview Office 7.3 and newer.


Solution 1:

    Here is a way to work-around this problem:
	1)  copy xc4000.fpn into the local directory
	2)  delete (or comment out) the line:
		clocksyms bufg bufg bufg bufg
	3)  create a Pad Symbol for bufgp and bufgs by adding the following
	    lines to the "Pad symbols" section of the xc4000.fpn file:

	symbol clkbuf bufgp
	pins in i
	pins out o
	symbol clkbuf bufgs
	pins in i
	pins out o

	4)  create a design.fpn file in the project directory with the following
 instructions:

		clocksyms bufgp bufgp bufgs bufgs
		| a comment
		clock 1 rst
		clock 2 clk
		clock 3 inn[0]
		clock 4 inn[1]

Note that the line:
     clocksyms bufgp bufgp bufgs bufgs
   causes the two first clocks to be driven by a BUFGP and the two following
   ones by a BUFGP.

Note that the line:
      clock 1 rst
    causes Viewsyn to treat the input signal "RST" as a clock (with the
    highest priority). It will then use a BUFGP for it.



End of Record #973