Examples of KiCad projects you should learn from

Now that you have installed your instance of KiCad let’s start your familiarisation with it by looking at one of the examples that come with it. Browse to the KiCad demos folder, and access the one titled 'pic_programmer' (Figure 5.1).

The demo project folder contains several files that make up the project. The ones to focus on for now have the extensions ‘pro,’ ‘kicad_pcb’ and ‘sch.’ The file with the ‘pro’ extension contains project information. The ‘kicad_pcb’ file contains layout information. The files with the ‘sch’ extension contain schematic information. There are two ‘sch’ files because this project includes two schematics.

Project file and main window

Double-click on the ‘pro’ (project) file. The main KiCad window will appear. This window is the launch pad for the other KiCad apps, like Eeschema (the schematic editor) and Pcbnew (the layout editor). You can see the main KiCad window in Figure 5.2.

The main KiCad window shows the project files in the left pane, the various app buttons in the top right pane, and various status messages in the bottom right pane.

Eeschema - the schematic editor

Let’s explore the schematic of this demo project. In the top right pane, click on the first button from the left. This button will start the Eeschema app, the schematic layout editor. You should see the editor as in the example in Figure 5.3.

There are a few things going on here. At first, this window might seem overwhelming. Don’t worry about the various buttons and menus, just concentrate on the schematic itself. Look at the various symbols, like those for the diodes, the transistors, and the operational amplifiers. There are symbols for resistors, and connectors, with green lines connecting their pins. Notice how text labels give names to the symbols, but also to the wirings between pins. Notice how even the mounting holes, at the bottom right side of the schematic, have names. Even though these mounting holes are not electrically active, they are depicted in the schematic. The values of the capacitors and resistors are noted, and any pins that are not connected to other pins are marked with an ‘x’. 

In the right side of the schematic, there is a rectangular symbol with the title ‘Sheet: plc_sockets’ (Figure 5.4). 

Double click on it. What happened?

This symbol is a link to another sheet, which contains additional symbols that are part of the same schematic. It looks like the example in Figure 5.5.

KiCad’s schematics can span over multiple sheets. If your schematic is too large to comfortably fit in one sheet, just add more (you will learn how to do this in this book). 

I encourage you to spend a bit of time to study this schematic. You can learn a lot about how to draw good schematic diagrams by studying good schematic diagrams, just like you can learn programming by studying good open source code.

Pcbnew - the layout editor

Go back to the main KiCad window. Click on the third button from the left, the one that looks like a PCB. This will launch Pcbnew, the layout editor. The window that appears will look like the example in Figure 5.6.

Again, don’t worry about the various buttons and menus, just concentrate on the layout inside the sheet. Use the scroll wheel of your mouse to zoom in and out, and the Alt+right mouse button to pan (you should also be able to pan by holding down the middle mouse button). Zoom in and look at some of the layout details, such as the pads, how they are connected to traces, the names that appear on the pads and traces, and the colours of the front copper and back copper layer traces. Note: in Linux, panning is done with the middle mouse button, and the alt key is not used.

Also, compare how a footprint in the layout compares to the symbol in the schematic. You can see a side-by-side comparison in  Figure 5.7.