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Electronics Design

This week is all about diving into Electronics Design online PCB design tool. As a beginner developing a generic RP2040-based expansion board.

Working with the Seeed Studio XIAO RP2040 is exciting—it’s small, powerful, and versatile. But let’s be real, those tiny pins can be a pain when prototyping. So, I built an expansion board that makes wiring easy, eliminates messy breadboards, and gives direct access to all power, GPIO, and communication ports.

This board makes plug-and-play prototyping simple, allowing easy connections for sensors, displays, communication modules, and power sources—all in a neatly organized layout.

Why Build This?

While working on different projects, I noticed a few pain points when using the XIAO RP2040: ❌ Limited power pins – Not enough GND, 3.3V, or 5V outputs for multiple sensors.

❌ Messy wiring – Directly connecting to the XIAO RP2040’s small pads is tricky.

❌ Difficult sensor connections – I2C, SPI, and UART needed better breakout options.

So, I decided to fix all these issues by creating a compact, beginner-friendly expansion board that:

✔️ Breaks out all GPIOs into accessible headers

✔️ Adds multiple power rails (5V, 3.3V, GND) for external modules

✔️ Includes dedicated ports for I2C, SPI, and UART devices

✔️ Provides a debugging LED for quick testing

✔️ Uses screw terminals for secure external connections

✔️ Includes jumper headers for flexible wiring

Getting Started with EasyEDA

This week, I stepped into EasyEDA for the first time, and let me tell you—it’s a pretty solid tool for designing circuits. It’s got everything: a schematic editor, PCB layout tool, and even a simulation feature to check if your circuit will work before you physically build it.

Key Features of EasyEDA: 1. Schematic Editor – Draw circuit diagrams with prebuilt components. 2. PCB Layout Editor – Convert schematics into a printable PCB layout. 3. Simulation – Test how your circuit will function before making it. 4. Component Library – Access thousands of electronic parts. 5. Auto Router – Automatically routes PCB traces to avoid errors.

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Designing the Expansion Board

1) Setting Up Power Rails

To ensure smooth power distribution, I first broke out the power pins into multiple headers: - 5V header – Powers external modules that require 5V. - 3.3V header – Used for sensors and logic circuits. - GND header – Provides multiple ground points to prevent loose connections.

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2) Expanding GPIO Access**

The XIAO RP2040 has 11 GPIO pins, and instead of working directly with tiny pads, I extended them to header pins for easy access.

  • Each GPIO (GP0 - GP11) is broken out into labeled headers.
  • Male & female headers allow flexibility for jumper wires and direct connections.
  • Clear labeling prevents confusion when wiring sensors and components.

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3) Debugging LED for Quick Checks

Sometimes, you just want to test if a GPIO is working without setting up an entire circuit. To solve this, I added an onboard LED connected to GPIO6 for debugging.

  • Wired a 330Ω resistor in series to prevent excess current.
  • Added a jumper header to enable/disable the LED easily.

4) Dedicated Ports for I2C, SPI, and UART

Connecting sensors, displays, and communication modules should be effortless. So, I created separate breakout headers for I2C, SPI, and UART, making sure they are plug-and-play ready.

  • I2C (For Sensors Like OLED, MPU6050, etc.)

SDA (GP4) → I2C SDA header

SCL (GP5) → I2C SCL header

3.3V and GND → I2C VCC & GND

  • SPI (For Displays, SD Cards, etc.)

MISO (GP8) → SPI MISO header

MOSI (GP10) → SPI MOSI header

SCK (GP9) → SPI SCK header

CS (GP7) → SPI CS header

  • UART (For Bluetooth, GPS, etc.)

RX (GP0) → UART RX header

TX (GP1) → UART TX header

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5) Screw Terminals for External Wiring

For a more permanent setup, I added screw terminals for: ✅ Extra GND connections ✅ Extra 3.3V & 5V outputs ✅ Two additional GPIO terminals

6) Jumper Headers for Flexible Configurations

To keep the design adaptable, I included jumper headers that: - Allow enabling/disabling the debugging LED. - Let me switch power between 5V and 3.3V for certain components.