# Kicad Tips & Tricks

Summary

• KiCad Custom Components
• KiCad Ground Plane
• Create a USB plug from the PCB

# KiCad Custom Components

Version: 9.0
Scope: Schematic Editor (Eeschema)
Target Component: MCU (e.g., WCH CH552G - SOP16 Package)

# 1. Library Initialization

Before creating a symbol, it is best practice to create a project-specific library to keep dependencies portable.

1. Open the Symbol Editor from the main KiCad project window.
2. Go to File > New Library.
3. Select "Project" in the dialog box (this ensures the library is saved within the project folder).
4. Name the library (e.g., NetRun_Components.kicad_sym) and save it.
5. The new library will appear in the left-hand list.

# 2. Creating the Symbol

1. Right-click on your new library (NetRun_Components) in the list.
2. Select New Symbol.
3. Symbol Properties configuration:
   • Symbol Name: CH552G
   • Default Reference Designator: U (Standard for ICs/MCUs).
   • Derive from existing symbol: Leave empty (start from scratch).
   • Click OK.

# 3. Drawing the Body

1. Select the Add Rectangle tool (or press S).
2. Draw a rectangle centered on the crosshair anchor.
   • Tip: Ensure the rectangle is large enough to accommodate 16 pins with readable spacing.
3. Right-click the rectangle > Properties to adjust the background fill (optional: "Fill with body background color").

# 4. Defining Pins (Pin Table Method)

The most efficient way to add pins is using the Pin Table rather than placing them one by one.

1. Click the Pin Table icon (looks like a spreadsheet) in the toolbar.
2. Add all 16 pins according to the datasheet.
3. Crucial Configuration: Set the Electrical Type correctly for ERC (Electrical Rules Check).

Note: Pins 12/13 (USB) are essentially Data pairs, often marked as Bidirectional.

# 5. Finalizing and Saving

1. Close the Pin Table.
2. Arrange the pins visually if needed (drag and drop).
3. Position the Value (CH552G) and Reference (U) text fields outside the rectangle.
4. Press Ctrl+S to save.

# 6. Integration

1. Open your main Schematic Editor.
2. Press A to add a component.
3. Search for CH552G (it should appear under your NetRun_Components library).
4. Place it on the sheet.

# KiCad Ground Plane

Version: 9.0
Scope: PCB Editor (Pcbnew)
Objective: Create a global GND plane to automatically connect all GND pads via thermal reliefs.

# 1. Prerequisite

Ensure your schematic has been updated to the PCB (F8) and that you have a Net named GND in your netlist.

# 2. Defining the Zone

1. Select the Add Filled Zone tool from the right toolbar (shortcut: Ctrl+Shift+Z).
2. Click on one corner of your board outline (outside or exactly on the Edge.Cuts line).
3. The Copper Zone Properties dialog will open. Configure as follows:
   • Layer: Select F.Cu (Front Copper) and/or B.Cu (Back Copper).
     • Note: For a 2-layer board, it is common practice to flood both layers with GND.
   • Net: Search for and select GND.
   • Smoothing: Fillet (Optional, for rounded corners).
   • Electrical Properties:
     • Clearance: 0.2mm (or typically follows Design Rules).
     • Pad Connections: Thermal relief (Makes soldering easier by not dissipating heat too fast).
4. Click OK.

# 3. Drawing the Outline

1. Your cursor is now in drawing mode.
2. Trace a rough polygon around your entire PCB.
3. You do not need to be precise; you can draw a large rectangle outside the PCB Edge.Cuts. KiCad will automatically clip the copper to the board edge.
4. Double-click to close the polygon loop.

# 4. Filling the Zone

1. At this stage, you only see the hatched outline (the zone is empty).
2. Press the B key on your keyboard (Refill all zones).
3. KiCad will calculate the geometry and flood the board with copper.

# 5. Verification

1. Check Connectivity: Look at your GND pads (e.g., on the USB port or MCU). They should now be connected to the surrounding copper by 4 small spokes (Thermal Reliefs).
2. Check Ratnest: The thin white lines indicating unconnected GND nets should disappear.
3. Visibility: If the filled copper makes it hard to see tracks, you can toggle the display of zone fills using the "Show only zone boundaries" button on the left toolbar.

# 6. Troubleshooting

• Islands (Dead Copper): If a part of the zone is not connected to the main GND point, KiCad might remove it (depending on settings) or leave it floating.
  • Fix: Use "Vias" to stitch the Top GND plane to the Bottom GND plane to ensure continuity everywhere.
• DRC Errors: Run the Design Rules Checker to ensure the copper pour doesn't create shorts or violate clearance rules.

# Create a USB plug from the PCB

Version: 9.0
Scope: PCB Editor (Pcbnew)
Objective: Create a USB plug from the PCB

First you need to open the Symbol Editor, then create a new library [global]. Once you're on the Symbol Editor, you can create a new symbol.

# Add Pins

1. Click on the pin tool
2. Add pins with the following properties:

3. Add rectangle and fill it with background color
4. Add extra text for later use.

# Create Footprint

1. Footprint Editor
2. Create a new library [global]
3. Create a new footprint
4. Add pads with the following properties:

# Create PCB

1. Add the USB symbol to the schematic
2. Link the footprint to the symbol
3. Open the PCB Designer
4. Import Schematics to the PCB

For this example, I created a rectangle using the Edge Cuts of the PCB of 40mm x 12.2mm.