Data Sheet

PCB Layout
101
A useful trick once we have specified our origin is to use the Goto-XY command on
the View Menu to move the mouse to the exact location we want to place position
sensitive parts. This command will automatically switch between X-Y or Radius-
Theta depending on whether you are in polar or cartesian co-ordinates.
Proteus has a default grid and will snap objects onto the grid, making it easy to form
connections and control board layout. There are four hotkeyed snap settings for both metric and
imperial units, changeable from the View Menu or by keyboard shortcuts. It follows that
changing the snap setting to a lower unit will allow finer granularity, whereas raising the snap
setting will make it easier to select objects at higher zoom levels. It is not advisable to change
the snap settings regularly through a design but rather to choose the highest appropriate setting
for the board you are working on.
You can change the four default snap settings via the Grids command on the Technology Menu.
Grid settings can be set according to the users requirement
The grid display itself can be toggled between off, dots and lines via the ‘G’ key on your
keyboard, whilst the colour of the grid can be configured from the Displayed Layers Dialogue
(View Menu).
Placing Components and the Ratsnest
Now that we’ve handled all the basics we can finally start to get our components on the board.
The following screenshot shows a fully placed board and we can use this to get our
approximate positioning. Since it is a fairly simple board we are going to place manually but it is
worth noting that Proteus includes a fairly sophisticated auto-placement facility that includes
component grouping (e.g. powersupply, usbengine, etc.) and floorplanning on the layout.