Answers Database

NGDANNO 1.3: Mode pin MD1 always outputs "z" in timing simulation


Record #3012

Product Family:  Software

Product Line:  Merged Core

Problem Title:
NGDANNO 1.3: Mode pin MD1 always outputs "z" in timing simulation


Problem Description:
Keywords: ngdanno, md1, mode pin, tri-state, 3-state

Urgency: standard


If a design uses the mode pin MD1 as a user output, then timing simulation
(post par ) may result in MD1 stuck in a 3-state ("z") output.

Reference: 101548


Solution 1:

This is not a bug in ngd2vhdl, ngd2ver, or ngd2edif; the problem is
with NGDANNO.
If NGDANNO is run without giving it the .ngm file (produced by MAP),
then MD1 will be configured so that the internal GTS is always
active in simulation (even if you do not use GTS in your design, the
simulation model of the output will still contain a pad driven
by an 3-state driver with a GTS disable).

The solution is to run NGDANNO with the .ngm file (if using Design
Manager, make sure that "Correlate Simulation Data to Input Design"
is checked in Design->Implement->Options->Implementation_Edit_Template->
Interface). You will need to regenetate the simulation netlist
(ngd2ver, ngd2vhdl, etc). after this step.




End of Record #3012