Answers Database

XC3000/XC4000/XC5200: How to select cmos input thresholds for FPGAs


Record #1065

Product Family:  Software

Product Line:  FPGA Core

Problem Title:
XC3000/XC4000/XC5200: How to select cmos input thresholds for FPGAs


Problem Description:
Keywords: THRESHOLD, TTL, CMOS, INPUTS, FPGAs

The input thresholds for FPGAs can be set to either CMOS
or TTL (TTL is the default)

The setting is a globally selectable input threshold
(all CMOS or all TTL), selectable when you run makebits.
If you type "makebits -h", you will see two ways of doing this :

-c

or

-f Input: CMOS


Solution 1:

FROM DOS:

For 2000 and 3000 use:
makebits -c

For 4000 and 5200 use:
makebits -f inputs:cmos

IN WINDOWS DESIGN MANGER 6.0
select Design -> implement -> configuration, edit template
then click on cmos under inputs threshold:





End of Record #1065