FAB ACADEMY 2026 · WEEK 6

Electronic Design

Custom PCB design including microcontroller integration, power regulation, input buttons, and communication interfaces.

Electronic Architecture XIAO RP2040

This week focused on designing a custom electronic board to support my final project. The design integrates a microcontroller, regulated power supply, input buttons, and communication headers.

The objective was to create a modular and expandable PCB that can be reused for control, sensing, and future expansion.

KiCad Workflow Electronic CAD

The entire electronic design was developed using KiCad. This open-source Electronic Design Automation (EDA) software allows schematic capture, PCB layout design, component management, and fabrication file generation.

1. Project Creation

The first step was creating a new project inside KiCad. This automatically generates:

  • .kicad_pro → Project file
  • .kicad_sch → Schematic file
  • .kicad_pcb → PCB layout file

This structure ensures that schematic and PCB remain synchronized.

2. Schematic Editor

Tool Used: Schematic Editor (Eeschema)

In the schematic editor, I created the logical representation of the circuit.

Key Tools Used:

  • Add Symbol: Inserted XIAO RP2040, regulator, resistors, capacitors, buttons.
  • Wire Tool: Connected electrical nets.
  • Power Symbols: Added GND, +7V, Regulator OUT.
  • Net Labels: Named connections to keep schematic clean.
  • Annotate Tool: Automatically numbered components (R1, C1, U1).
  • Electrical Rules Check (ERC): Verified missing or incorrect connections.

ERC was critical to detect floating pins and power issues before moving to PCB layout.

3. Assigning Footprints

Tool Used: Assign Footprints

After finishing the schematic, each symbol was assigned a physical footprint.

For example:

  • Resistors → 1206 SMD footprint
  • Capacitors → 1206 SMD footprint
  • Voltage regulator → SOT-223 or equivalent
  • XIAO RP2040 → Header-based footprint

This step links the logical schematic to physical PCB components.

4. PCB Layout Editor

Tool Used: PCB Editor (Pcbnew)

After importing the schematic into the PCB editor, all components appeared unplaced.

Key Steps:

  • Defined board outline.
  • Placed microcontroller centrally.
  • Positioned regulator near power input.
  • Grouped buttons logically.
  • Routed power traces thicker than signal traces.

Trace routing was performed manually to maintain signal clarity and reduce noise, especially in power lines.

5. Design Rule Check (DRC)

Tool Used: Design Rule Checker

DRC verifies:

  • Minimum trace width
  • Clearance between traces
  • Unconnected pads
  • Overlap errors

Running DRC ensured the PCB was manufacturable and electrically correct before fabrication.

6. Generating Fabrication Files

Tool Used: Plot → Gerber Files

The final step was exporting:

  • Gerber files (.gbr)
  • Drill files (.drl)
  • Board outline

These files are required for PCB manufacturing.

Schematic Design System Diagram

Schematic

The schematic was organized into functional blocks for clarity.

SolidWorks Drawing Piece 1
Download .kicad_sch

The schematic was divided into logical blocks:

  • Microcontroller (XIAO RP2040)
  • Power Supply Regulation
  • User Input Buttons
  • Communication Headers (I2C / UART)
Microcontroller Core Control

XIAO RP2040

The XIAO RP2040 was selected because it provides:

  • Dual-core ARM Cortex-M0+
  • Compact footprint
  • Multiple communication protocols (I2C, SPI, UART)
  • PWM support for motor and servo control

The board connects:

  • Digital inputs (Buttons B1, B2, B3)
  • I2C header for expansion
  • UART header for debugging
  • External regulated power input
Power System Regulation

Voltage Regulation

The board includes a voltage regulator to convert +7V input into a stable regulated output suitable for the microcontroller.

  • Input: +7V external source
  • Voltage regulator with input/output capacitors
  • Power LED indicator
  • On/Off switch

Capacitors were included on both input and output sides of the regulator to ensure voltage stability and reduce ripple.

Component Purpose
Regulator Voltage stabilization
Input Capacitor Filter voltage spikes
Output Capacitor Improve load response
Power LED Visual power indication
Input Interface Buttons

Push Buttons

Three push buttons were integrated for user interaction. Each button includes a resistor for pull-down configuration to ensure stable logic levels.

  • B1 – Primary input
  • B2 – Secondary input
  • B3 – Auxiliary control

The design ensures noise reduction and stable digital readings.

Communication I2C / UART

Communication headers were added to allow:

  • I2C peripheral expansion
  • UART debugging
  • Future sensor integration

This modular approach allows the board to scale with the final project.

Final Project Integration

This electronic design forms the core control board of my final project. It centralizes power regulation, user interaction, and communication into a compact PCB architecture.

The modular design ensures adaptability and future expandability.

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