Data Sheet

PCB Layout
133
Editing a Route
It is often the case that routes need to be nudged or moved into position after placement and we
definitely don’t want to be deleting and replacing routes or parts of routes all the time. To take
an example, let’s move our track lower down the board a little, towards the bottom board edge.
Start by right clicking on the horizontal section (segment) of the track; this is the section we
want to move. Next, select Drag Route from the resulting context menu, move the mouse down
to ‘pull’ the track into the desired location and then left click again to commit placement.
Moving tracks works as we’ve seen on a track segment. Using the Trim Manually
option on the context menu for a track allows you to define your own segment and
you therefore have complete flexibility with altering track topology.
You may want to perform operations on multiple tracks at one time. The obvious example of this
is changing the width of the track(s) and/or the via style used when routing them. You can do
this by first switching to selection mode, then using CTRL+left click to select and finally by right
clicking on any of the selected tracks to access the context menu.
Layer Pairs and Manual Routing
The track we have placed is of course only on top copper, whereas we often want to via up and
down through the board when routing. Proteus handles this with a concept called Layer Pairs.
This means that every layer on the board has an associated layer so that via destinations are
known during placement. For a two layer board this is obvious with top copper being associated
with bottom copper and vice versa but with multi-layer boards configuring the layer pairs
(Technology Menu – Layer Pairs) can be an important step.
Don't be surprised to see much of layer pairs dialogue disabled. The available layer
pairs are restricted to the signal copper layers set up in your layer stack.
In our case, the default assignments are correct and no action is required. Let’s place a couple
more routes manually to see how this works. We’ll look at connecting pins 1 and 2 of the J2
connector which are the transmission lines from the USART on the dsPIC processor.
We’ll start with pin 1 and route from the pin on the bottom copper layer. Make sure that you
have track mode selected and then hit the space bar on the keyboard, noticing that this will
toggle the layer between the two layers associated as a layer pair. If you have ended up on top
copper simply hit the space bar again to set the layer to bottom copper.