Week 06 - Electronics Design

 Posted on February 28, 2026  |  

Introduction

For this week, I designed a simple PCB as a way to test the full electronics design workflow in KiCad, from schematic to a fabrication ready board.

Learning Outcomes

Select and use software for circuit board design: I used KiCad for schematic and PCB layout.

Demonstrate workflows used in circuit board design: I followed schematic → footprint assignment → PCB layout → routing → ERC/DRC → export.

Hero Shots

Hero shot of the PCB Hero shot of the PCB

PCB Overview

The idea is that every time the button is pressed, the board generates a random color result (with different probabilities). If the rare “green” result appears, the board plays a short winning sound.

This allowed me to practice correct component selection, footprint assignment, routing, ground strategy, and ERC/DRC checking in a complete PCB design process.

Group Assignment

Group assignment page:

https://week-6-group-assignment-f3155c.fabcloud.io/

Software Used

KiCad (schematic + PCB layout)

Schematic Design

Creating the schematic

I started by creating the schematic in KiCad and organizing the board into simple blocks:

  • Xiao ESP32-C3 module: main board
  • Button input: Push button, Omron (SW1)
  • RGB LED output: RGB CreeLed PLCC4 (D1)
  • Speaker output: Buzzer (LS1)
  • Resistors: 125,50,50 Ohm Resistors (R1, R2, R3) for the RGB LED channels
  • Power: 3V3 and GND

I also:

Checked the datasheet of CRGB CreeLed PLCC4 as I was not sure if it was suitable for this project, even if it were, I did not know how it worked. https://downloads.cree-led.com/files/ds/h/HB-CLV1A-FKB.pdf . I learnt that it is a common anode rgb led which meant that a single power line was then distributed into 3 pins which are r,g,b. I have to remember this when doing the routing. This is a good example to check the datasheets of your components.

Resistor Calculations

At IF = 8mA:

  • Red forward voltage ≈ 1.9V
  • Green forward voltage ≈ 3.0V
  • Blue forward voltage ≈ 3.0V

(Values from Led’s datasheet)

Since my board operates at 3.3V (ESP32-C3 supply), resistor values must be calculated using Ohm’s Law.

Formula used:

R = (Vsupply − Vforward) / I

Target current per channel: ~10mA
This keeps brightness strong while staying safely below maximum ratings.

Red Channel

R = (3.3V − 1.9V) / 0.01A
R = 1.4 / 0.01
R ≈ 140Ω

Closest value used: 125Ω

Green Channel

R = (3.3V − 3.0V) / 0.01A
R = 0.3 / 0.01
R ≈ 30Ω

Closest value used: 50Ω

Blue Channel

R = (3.3V − 3.0V) / 0.01A
R ≈ 30Ω

Closest value used: 50Ω

Final Resistor Values Used

Red 150Ω
Green 33Ω
Blue 33Ω

By calculating each resistor separately:

  • Current is controlled properly
  • Brightness between channels is more balanced
  • The board behaves more predictably
  • The design reflects correct practice

Assigning symbols and footprints

Once the schematic was complete in my head, I used Krisjanis Rijnieks’s KiCad FabLib for the symbols. (https://gitlab.fabcloud.org/pub/libraries/electronics/kicad) You can follow its instructions to add the library to KiCad. After adding symbols, we will then be working on the footprints of every component.

At this stage I learned an important lesson:

I initially added parts without checking whether those exact components exist in our lab, and also without confirming the correct variant.Because many components have multiple similar labels/versions, selecting the wrong one can result in:

  • incorrect pad sizes
  • assembly problems later

Fix: Before finalizing the PCB, I verified:

  • that it has correct footprint
  • the physical size of the part
  • that the component is available in the lab

KiCad schematic Schematic designed in KiCad.

ERC (Electrical Rules Check) + fixing power flag issue

After finishing the schematic, I ran ERC to catch design issues early before moving to PCB layout.

During ERC, I realized I had not added PWR_FLAG symbols, so KiCad treated the power nets as if they were not being driven properly.
This created ERC warnings and made it clear that I should fix power handling before continuing.

Fix: I added the missing PWR_FLAG symbols and re-ran ERC to confirm the schematic was clean. erc

ERC tool giving no error.

PCB Editor (Placement + Routing)

Creating the board outline

After importing the design into the PCB editor, I first drew the board outline:

  • Outline layer: Edge.Cuts
  • Rounded corners for a clean shape

This step defined the final physical limits of the PCB and helped keep placement organized. roundededge

Example for a rounded edge cut.

Component placement

Before drawing connections, I placed components carefully to make routing easier.

Placement decisions:

  • ESP32-C3 near the center (main controller)
  • SW1 (button) near the edge (easy access)
  • D1 (RGB LED) placed clearly visible
  • R1/R2/R3 placed close to the LED to keep traces short
  • LS1 (speaker) placed to avoid long, messy traces

I also left enough space for soldering and avoided placing components too close together.

Routing (drawing copper connections)

After placement, I began routing the connections based on the schematic nets in F.Cu layer.

Trace width

I used a 0.4 mm trace width for routing. Line

Figure 4 — 0.4mm trace

Routing approach

While routing I focused on:

  • short, direct signal paths
  • avoiding unnecessary bends
  • making the PCB readable
  • minimizing crossings
  • NO 90 DEGREE ANGLES (Results in incostistent lines in the production.)

Ground plane (GND all over the board)

Instead of manually routing every single ground connection, I used a GND copper fill.

This made ground available across most of the PCB and gave me these advantages:

  • cleaner routing (less manual GND traces)
  • easier connections to ground pins
  • more stable board reference

PCB layout screenshot

PCB layout in KiCad

PCB layout view showing placement, routing, and ground fill.

DRC and Fabrication Readiness

DRC (Design Rules Check)

After completing routing and ground filling, I ran DRC to verify that the board can be fabricated.

This confirmed:

  • no shorts
  • no clearance issues
  • all nets routed correctly
  • board outline is correct

Passing DRC gave confidence that the PCB is fabrication ready. drc

DRC tool showing no error.

Exporting the manufacturing files

Finally, I exported:

SVG files

These files are not the standard outputs needed for PCB fabrication. Gerber files are mainly used but since I am new to this process, using svg is easier.

Reflection (What I Learned)

This week helped me understand that electronics design is not only connecting components, but also verifying the design step-by-step.

Key takeaways:

  • ERC helped me catch missing PWR_FLAG issues early
  • footprint selection must match real available components
  • component placement affects routing quality a lot
  • using a GND plane makes the PCB cleaner and easier to route
  • DRC is necessary to confirm fabrication readiness

Result: A complete KiCad PCB design with 0.4 mm routing, ground plane filling, ERC/DRC verification, and fabrication-ready exports.

Files

I included the original KiCad project files so the board can be edited or reproduced: Download the designs