Page 206 - Make Your Own PCBs with EAGLE from Schematic Designs to Finished Boards

FIGURE 8-7 Initial layout editor mess.

As you can see, as well as the shield outline in the “Dimension” layer, there is also a default
rectangular board area with the layout origin at its bottom-left corner. This rectangular board can be
deleted and the Arduino shield board moved so that the origin is at its bottom-left corner.

We can now start dragging the components onto the board, starting with the display and rotary
encoder, which we want to be fairly central to the board. We can also position the battery holder over
to the right edge of the board, rotating it so that the battery can be easily replaced.

The same argument applies to the screw terminal, which is located on the left of the board where
the other Arduino leads for USB and power are attached so that all the leads are on one side and easy
to access.
While giving the key components their initial positions, we also need to consider what is going on

beneath the board. For example, the Arduino Uno has a metal USB socket in the top-left corner (see
Figure 8-1). So we do not want any through-hole leads immediately above that, which might make
contact with the metal of the socket. The same applies to the center of the right-hand edge of the
shield, where there is a six-pin ICSP header poking up from the Arduino. This is another reason why
it is a good location for the surface-mount battery holder to be mounted on the top side.

With the key components positioned, the board will look something like Figure 8-8.