siliconchip.com.au Australia’s electronics magazine April 2019 71
Fig.1: a section
of a PCB we
are currently
working on,
where we
want to move
a large group
of components
to the right.Fig.2: AD19’s
Component
reroute feature
has been
enabled, so
after moving
them, most of
the external
tracks are still
connected
correctly, and
there are no
apparent
design rule
violations as
a result of the
move.Fig.3: here we tried to move CON2 with Component
re-route turned on; the tracks were originally parallel.
This only happened very occasionally, but it was quite
surprising when it did happen.
Fig.4: this shows where the Component re-route option can
be enabled or disabled in the Preferences. Click OK after
changing the setting for it to take effect.you may have to reroute all the tracks around those parts.
Component re-route is the solution to this. As the name
suggests, when this feature is enabled, tracks are re-rout-
ed whenever components (or a group of components) are
moved, reducing the need to do this manually.
Fig.1 shows a PCB we’re working on while Fig.2 shows
the result of moving a large group of components 5.08mm
to the right, with this feature enabled. You can see that
many of the tracks connecting these components to other
parts of the circuit have changed shape to preserve those
connections and prevent overlaps and short circuits.
Some of these tracks would need to be manually cleaned
up as they have become unnecessarily ‘loopy’, but it’s a
lot less work than re-routing all the tracks manually. Fig.3
further demonstrates how re-laid tracks do not always end
up finding the obvious paths. But the resulting layout is
still valid, even if non-optimal.
When this feature is enabled, there’s a brief pause after
each movement, while the track paths are recalculated ac-
cording to the current design rules. So you certainly don’t
want to have it switched on all the time. There are times
when you may even need to move a component out of the
way temporarily, in which case you don’t want the con-
nected tracks to follow.
This feature can be switched on and off via the Prefer-
ences dialog box (available either from the Tools menu or
the gear icon on the menu bar), under PCB Editor → Inter-
active Routing → Component re-route (see Fig.4).
Follow Mode for routing tracks
One routing feature which we would have certainly
used in the past, had it been available at the time, is the
Follow Mode for track placement. You might notice that
our PCB design for the Stackable LED Christmas Tree pub-
lished in the November 2018 issue (siliconchip.com.au/
Article/11297) has some curved tracks that gently follow
the contours of the board.
This was painstakingly done by creating an arc, assign-
ing it to a net, then adjusting it for the correct radius, and
finally connecting the tracks at each end. Both sides of the
PCB have a pair of stacked arcs, for a total of four, so this
took some time to accomplish.
AD19’s Follow Mode allows the interactive routing to
follow the contours of an object (which may be composed
of several smaller primitives such as lines and arcs). The
new version would have allowed us to simply start the
track, switch to Follow Mode to create a gentle arc along
the board edge, and then resume normal routing.
To activate Follow Mode, start routing a track as usual,
and then when you have reached the obstruction, move the
mouse pointer over the obstruction and press Ctrl-F. The
track will now consist of arcs and line segments following
the contour of the obstruction until the left mouse button
is clicked, after which normal routing resumes.
Interactive routing design rules are obeyed during Fol-
low Mode, of course, and the results can be seen in Fig.5.
In addition to this new feature, the routing algorithm has
been generally improved and seems to be slightly smarter