Answers Database

M1.5 EPIC: How to manually route signals


Record #4006

Product Family:  Software

Product Line:  FPGA Implementation

Problem Title:
M1.5 EPIC: How to manually route signals


Problem Description:
Keywords: EPIC, longlines, manual route, routing

Urgency: standard


  How do I manually route a signal in EPIC?


Solution 1:

MANUAL ROUTING IN EPIC

First, you should always autoroute connections whenever
possible. The EPIC autorouter uses a delay-based
algorithm to find the lowest delay path; this path isn't
always obvious to the user. The autorouter can also be
used to route from a route segment to a component pin
to do "guided" autorouting.

The resources that can be manually routed are signal pins, local lines, and long
 lines. A routing operation requires
selecting at least two of these resources then clicking
the Route push button. Pinwires are routed by selecting
their signal pins or the pinwire itself.

The trick to manual routing is to select the resources that
should be routed together IN THE ORDER THAT THEY SHOULD BE
CONNECTED. If you choose three resources (for example, a
signal pin, a local line, and a long line, in that order),
the manual router will attempt to connect the signal pin to
the local line, and then the local line to the long line.
If no connection is possible, an error message will be
displayed in the history area. You can route through
bidirectional PIPs or links in either an upstream or
downstream direction (i.e., towards or away from the driver
pin), but you cannot mix directions during a single route
command.

Stub trimming is a global attribute which, when set to TRUE,
draws only the portions of the local and long resources
which are visually relevant to the propagation of the signal.
This mode can be misleading since when zoomed in, a local or
long line resource can appear to be available when it is
actually used. Though stub trimming is set to TRUE by default
in EPIC, we recommend setting it to FALSE (in the Main Window
Attributes dialog box) during manual routing. Alternatively,
you can see whether an apparently unused line really is
unused by selecting the line and then the Info or Attrib
push button. NO SIGNAL indicates that the line is unused; a
net name associated with the line indicates that the line is
used.
To turn Stub trimming on or off, go to Misc->Post Main Attrs..
and select or deselect Stub Trimming.

Switch box connections are made by selecting the two local
lines which are to be connected. To know the local lines to
which another local line can connect, select the appropriate
switch box pin. This will highlight the possible connections
(some of these connections may not be possible because the
lines are used). The switch box connection display does not
interfere with manual routing and can be eliminated by
selecting that switch box pin again or by performing the
unhilite -all command. If it is necessary to make a bank shot
through a switch box, select the local line resources used by
the bank shot in the appropriate order and then perform the
route command.

If you make a mistake while selecting resources for manual
routing, you can deselect selected objects prior to
performing the route command. If something routes that you
want unrouted, select the signal name, signal pin, or route
segment that you want to unroute and perform the unroute
command. Unrouting a local line will free up that local line,
which means that any switch box connection to that line will
be unrouted also.





End of Record #4006