The design of the PCB schematic is the basis of the entire circuit board design, and the design of the circuit schematic will directly affect the subsequent work. In general, to design a circuit schematic, first set the parameters of the drawing in the schematic editor, then the overall planning of the circuit diagram, then place the components on the drawing and layout, wiring, preliminary PCB schematic After the drawing is completed, add comments and check and modify as needed, and finally print out the finished drawing. The following is a brief overview of the key steps in the schematic design flow.

1, create a new folder: create a new design database file and schematic file, and start the schematic editor.

2, set the drawing parameters: the user should set the drawing parameters such as the size, direction, and title bar format of the schematic drawing according to the complexity of the circuit design and the required drawing specifications. In addition, the user has to set the design information of the schematic as needed, such as the company name and the designer's name and date of the drawing.

3. Load schematic symbol library: Load the schematic symbol library containing the components required by the user to draw the schematic diagram into the schematic editor so that the user can find the required components.

4. Place and adjust components: Select the components required for drawing from the loaded schematic symbol library, place them one by one on the working platform, and then adjust the component position according to clear and beautiful design requirements. The next step of wiring work lays the foundation.

5, set the component properties: After the component layout is completed, the next step is to set the properties of each component. The properties of the component mainly include the serial number of the component, the package form and the component model.

 
6, schematic wiring: This process is the core of drawing PCB schematics. The user should connect the pre-placed components with electrically conductive wires, network labels, etc., so that the components can meet the electrical connection relationship designed by the user.

7, add a note: This process is mainly to make some corresponding description, labeling and modification of the PCB schematic, so that the drawing is beautiful and enhance its readability. This step can be omitted if the user does not need to add a comment.

8. Inspection and modification: Due to the original design problem or the carelessness of drawing the wire process, the initial schematic drawing of the PCB schematic is inevitably wrong, so the user must use the various calibration tools provided by Protel 99SE to complete the preliminary drawing. The circuit schematic is checked and further adjusted and modified to ensure that the circuit schematic is correct.

9, printout drawings: After the schematic drawing of the circuit is completed, in addition to the necessary preservation in the computer, the schematic diagram of the circuit diagram is often printed out for the designer to proofread, reference and archive.