Hardware Reference
In-Depth Information
The breadboard view is still visible and not too complicated. That is about to
change. The last thing to do is to connect the two headers, each one requiring
eight wires. The view will be extremely complicated, but don't worry; you will
see that there is a better way of looking at your circuit when this is done.
Connect all eight input/output pins of the two devices: P0 to P7 to each header.
My breadboard looks like the one illustrated in Figure 25-4. Note that I made
the wires a little clearer on the right but not on the left. With the I 2 C wires in
the way, it isn't easy to make something that is elegant. It might be possible by
spending a lot of time, but remember that breadboard schematics are all about
getting things done and not about understanding the electronics behind a design.
Figure 25-4: Breadboard final layout (Image created with Fritzing)
You now have a working breadboard design, but how do you turn this into a
shield? You can do this directly, but just before, it is time to look at the schematic.
Step 2: The Schematic
Reading breadboard designs isn't easy. The bottom left pin on both integrated
circuits are pulled low, but is this pin the ground? Is it an address? It is difi cult
to know without extensive knowledge of the integrated circuit itself, and there
are tens of thousands of designs. To understand what a circuit does, you have
to look at the schematic.
 
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