Miter problem in autorouting

[Neha Anu]

Hi all,

I want to miter some nets that are autorouted in specctra(allegro V 16.0).When mitered the some of the nets are mitering to diagonal corners,some others are not even if there are enough space in the board file (same with the case of rounded corners).I changed the setback length as a trail basis to check the behaviour of the miter command.Still the nets are not mitering.

Why the specctra is showing this nonpredictable behaviour?Is there any command that should be set before miter command?Can anyone plss give a solution to this??

Thanks
Neha

 

[edaedaeda]

You might be able to run this as a DO file.

unit inch
recorner diagonal 1 1 1
recorner diagonal 0.5 0.5 0.5
recorner diagonal 0.25 0.25 0.25
recorner diagonal 0.125 0.125 0.125

You can use other units and other values, but for best results always use a series of recorner
commands. Start with a large setback value, and halve the previous value for the next
recorner command in the series.

Below is a description of Miter:

pin <setback>
Specifies a cut or an arc at a pin (includes SMD) if the pin-to-turn distance is equal to
or greater than < setback>. The pin setback distance is measured from the center of
the pin to the turn.
slant <setback>
Replaces a wrong-way segment with a 135 degree segment, or with an arc, when the
wrong-way length is equal to or greater than < setback>.
tjunction <setback>
Specifies changes to 135 degrees at wire tjunctions, where < setback> is the distance
from the tjunction to the start of the cut. The default value for miter tjunction
< setback> is 0.5 inch.
bend <start_setback> <final_setback>
Specifies a cut or an arc at a bend. The < start_setback> parameter specifies the
initial setback distance that is attempted. When all attempts fail during this initial
iteration, the value of < start_setback> is divided by two and the new value is
attempted in all remaining 90 degree bends. This process continues. After all
attempts fail, the previous setback value is divided by two, and that new value is
used. When the divide-by-two operation results in a value less than < final_setback>,
the < final_setback> value is applied until all miter attempts fail and the miter bend
operation terminates. When only < start_setback> is supplied, < final_setback>
defaults to the minimum wire width.