⚡ WEEK 08 — Electronics Production

🧠 Project Overview

The individual assignment focused on the design, fabrication, and validation of a functional PCB capable of generating a LED roulette animation, using the microcontroller Seeed Studio XIAO ESP32C3.

This project integrates the complete electronics production workflow:

• Electronic design
• Digital fabrication
• Embedded programming
• System validation

Additionally, it applies the design rules obtained during the group assignment, ensuring manufacturability using a fiber laser process.

📦 Bill of Materials (BOM)

Component	Quantity	Description
XIAO ESP32C3	1	Main microcontroller
LEDs	7	Visual output for roulette
Resistors 220Ω	7	Current limiting
Copper PCB	1	Base material

🧩 Step 1 — Schematic Design (KiCad)

The design process began with the creation of a schematic in KiCad, defining the logical structure of the system.

Each LED was connected to an individual GPIO pin of the XIAO ESP32C3 through a 220Ω resistor, ensuring proper current limiting and protecting both the LEDs and the microcontroller.

Key design considerations:

• Correct LED polarity (anode/cathode)
• Selection of GPIO pins with digital output capability
• Clean and readable schematic organization

An Electrical Rule Check (ERC) was executed to detect errors such as:

• Unconnected pins
• Short circuits
• Incorrect net definitions

📸 Evidence:

🧠 Step 2 — PCB Layout Design (KiCad)

After validating the schematic, the design was transferred to the PCB editor.

Components were arranged strategically, placing the LEDs in a square configuration to simulate a roulette effect visually.

Routing strategy:

• Minimize trace length to reduce resistance
• Avoid crossing traces
• Maintain spacing ≥ 0.2 mm (based on group characterization)
• Ensure accessibility for soldering

All design decisions strictly followed the design rules defined during the group assignment, ensuring compatibility with the laser fabrication process.

📸 Evidence:

🎨 Step 3 — File Preparation in Inkscape

The PCB layout was exported and processed in Inkscape to prepare it for laser fabrication.

This step is critical because the laser interprets vector graphics directly, meaning any graphical inconsistency results in fabrication errors.

Detailed workflow:

• Export PCB traces from KiCad as SVG
• Open file in Inkscape
• Convert all traces to pure black
• Ensure background is white
• Remove labels, text, and unnecessary layers
• Convert strokes into filled paths
• Verify line continuity
• Export final file

Key considerations:

• No grayscale allowed
• Closed paths required
• Clean geometry ensures correct engraving

📸 Evidence:

⚙️ Step 4 — Image Processing & Toolpath Generation (Fab Modules / Mods)

The processed image was converted into machine instructions using Fab Modules (Mods).

This step translates visual design into toolpaths, defining how material is removed.

Workflow in Mods:

• Load PNG image
• Verify DPI and scale
• Adjust threshold (black/white separation)
• Define tool diameter
• Set cut depth and offsets
• Configure feed rate
• Generate preview
• Export G-code

Critical parameters:

• Tool diameter → defines minimum trace size
• Offset → defines copper removal area
• DPI → ensures correct scaling

Preview validation was essential to avoid:

• Broken traces
• Overcut areas
• Missing geometry

📸 Evidence:

🔥 Step 5 — Laser Engraving Process

The PCB was fabricated using a fiber laser engraving process, where copper is removed to define conductive traces.

Workflow:

• Fix PCB on machine bed
• Adjust focus height
• Import design into software
• Configure parameters
• Execute test engraving
• Run full engraving
• Inspect results

Parameters used:

Power	50%
Speed	700 mm/s
Frequency	35 kHz
Passes	2

Observations:

• Excess power damages substrate
• Low power leaves residual copper
• Multiple passes improve quality

📸 Evidence:

🕳 Step 6 — Drilling Process

Process:

• Identify hole positions
• Select correct drill bit
• Align drill precisely
• Apply controlled pressure
• Clean debris

Risks:

• Pad lifting
• Misalignment
• Structural damage

📸 Evidence:

✂️ Step 7 — PCB Cutting

Steps:

• Import outline vector
• Align with PCB
• Configure parameters
• Execute cut

Alignment accuracy was critical to avoid damaging traces.

📸 Evidence:

🔩 Step 8 — Soldering

Process:

• Preheat soldering iron
• Apply solder to pads
• Place components with tweezers
• Heat and fix joints
• Inspect connections

Key considerations:

• Avoid cold joints
• Prevent solder bridges
• Verify LED polarity

📸 Evidence:

💻 Step 9 — Programming

The system was programmed using Arduino IDE.

The code implements:

• Sequential LED activation
• Acceleration effect
• Final blinking pattern

This simulates a roulette animation.

📸 Evidence:

🧪 Step 10 — Testing and Validation

The system was tested to verify full functionality.

Results:

• All LEDs responded correctly
• No short circuits detected
• Stable operation
• Smooth animation achieved

📸 Evidence:

📸 Step 11 — Hero Shot

A final high-quality image was captured showing the working PCB.

This image represents:

• Final result
• Functional validation
• Integration of all processes

📸 Evidence:

📂 Download Files

• PCB Design Files
• SVG File
• PNG File
• Arduino Code (.ino)

🧠 Final Reflection

This project demonstrated that PCB fabrication is not only a design challenge but also a manufacturing challenge.

The fiber laser method provides:

• Speed
• Clean process
• Flexibility

However, it requires:

• Precise calibration
• Understanding of thermal effects
• Iterative testing

🧾 Conclusion

This assignment successfully integrated the complete workflow of electronics production.

The use of:

• KiCad (design)
• Inkscape (processing)
• Fab Modules (toolpath generation)
• Fiber laser (fabrication)

enabled a seamless transition from digital design to physical implementation.

The final result — a fully functional LED roulette PCB — confirms the effectiveness of the workflow and validates the use of the XIAO ESP32C3 in embedded systems.