Data Sheet

PCB Layout
173
Remember to hit the escape key on your keyboard when you have finished numbering pin 44 to
exit assignment mode.
It’s common to place a small dot beside pin one and you can do this via the 2D Graphics circle
icon. Make sure that the Layer Selector is on Top Silk and turn the snap setting down to
minimum (CTRL+F1) to achieve finer control over the size.
Place a small dot where Pin 1 is
The final step is to specify where we want the origin of the device to be (for placement
purposes) and where we want the silkscreen graphics for the package reference to appear.
Both of these are done with markers.
Select marker mode and make sure that ORIGIN marker is highlighted in the Object Selector.
You’ll recall that we used this as a reference point earlier but its real job is to specify the origin
of the component for placement and rotation. This is really a decision for the user but typically
the origin is either pin 1 or the centre of the component. For simplicity here, we will place the
origin on pin 1; left click to begin placement, move the mouse over the centre of pin 1 and left
click again to commit the origin marker.
Origin marker placed
Now, change the marker type to be REFERENCE in the Object Selector. The Reference marker
dictates where the component reference (e.g. U1, R12, C3) is placed by the software relative to
the component. Again, this is very subjective but we’ll set it above and slightly to the left of the
part.