In a circuit, We must draw a circuit schema (schematic) to specify connections of components with each other. In this part, we will learn how to draw a schematic. For this, we will use Eeschema.
The schematic program of KiCAD is Eeschema. To open Eeschema program, click on the Schematic layout editor icon in the KiCAD project window. If you have not created your project, follow the instructions in Chapter 1.
After opening Eeschema, we come up with an area where we can create a circuit diagram in A4 size. At the bottom right of this page is a section with information about the circuit diagram.
To edit this section, click the icon in the top toolbar and enter the date, revision, circuit name, company name as below. You can also add the designer’s name or license. In the left section, you can set the page size and orientation.
Now let’s add the necessary circuit elements for the circuit. To do this, click the symbol on the right toolbar. Let’s select the symbols below and turn them on.
Finally, click on the symbol to add a ground to the circuit, and let’s type GND in the search.
One of the best features of KiCAD is the shortcut keys. We move the mouse pointer over the desired symbol and we can perform the operation (moving, rotating, copying, deleting, mirroring, changing symbol value …) with just one click. For example, we can press M (Move) for moving, R (Rotate) for rotation, C (Copy) for copying, V (Value) for changing symbol value.
After setting the position of our symbols, we can start the drawing path by pointing to the end of one of the symbols we want to combine and pressing W (Wire). After the process, you can exit the drawing mode by pressing Esc.
After connecting the symbols, we can adjust the values of the symbols (such as the value of the resistor, the voltage of the battery). To do this, point to our symbol and click the V (Value) button to enter the value. We can enter 330 or 330R for the resistor.
Finally, let’s take our circuit into a rectangle. In fact, this is a process used to reduce the complexity of the circuit in large projects. To do this, click the symbol on the right toolbar to enter our circuit into a rectangle, and to add a name, click the Place tab from the top menu, click on the Graphic Text symbol or press the T (Text) key to enter the name.
Once our circuit is complete, we need to assign reference values for the symbols of our circuit. So each symbol must have its own number. To do so, click on the symbol from the top toolbar and we can change the settings in the pop-up window, but for now it is sufficient to remain the default. Click the Annotate button to complete the referencing process.
We can now associate the schematic symbol with the marks of the elements on the PCB. To do this, click on the icon from the top toolbar and select the elements according to the size and type (SMD or THT).
Finally, we need to create a document with the extension * .net in order to communicate to Pcbnew what elements and how these elements are linked. To do this, we click on the symbol from the top toolbar and click the Generate Netlist button without changing any settings.
Congratulations! You have finished Chapter 2, Schematic creation. With more experience, you will improve your ability to schematic creation. You can now continue with Chapter 3.