Week 06

Electronics Design

This week we worked on understanding how circuits work, simulating the way the circuits would work and how we can build a PCB. This includes learning about the different types of components used for building the circuits.

TOOLS

KiCad

Personal and Group Assignment

This week’s personal assignment was to design a circuit, run a simulation and design the PCB, while document the process.

Group Assignment

Here’s the link to our group assignment of this week.

What is electronics design?

It is the engineering process of creating, developing, and integrating electronic circuits and components (like resistors, transistors, and ICs) to build functional systems.

What does it work for?

It helps us create functional, reliable, and manufacturable electronic circuits and systems for industries like consumer electronics, automotive, healthcare, and telecommunications. It transforms concepts into working prototypes by defining, simulating, and testing PCB layouts, components, and embedded systems, ensuring they meet performance, safety, and cost requirements.

Understanding KiCad

To design the PCB for the dog wearable for my final project, I used KiCad. It is an open-source Electronic Design Automation (EDA) software. For Fab Academy, it's crucial to understand that designing a board here is not a single step, but a three-part workflow:

The Core Workflow

KiCad divides the design process into distinct environments that must be completed in order:

Eeschema: The logical editor. Here you draw the schematic using abstract symbols (like a triangle for an LED).
Footprint Assignment: The bridge between logic and reality. You tell KiCad that the abstract LED symbol is specifically a 5mm Through-Hole LED physically.
Pcbnew: The physical layout editor. Here you arrange the real components and draw the copper traces.

Logical Design

When designing the circuit for the XIAO RP2040 and the MPU6050, keeping the schematic readable was a priority.

Net Labels over Wires

Instead of drawing a web of messy green lines, I used Net Labels (like SDA and SCL for the I2C communication). KiCad automatically connects any pins sharing the same label.

Before moving to the PCB, I ran the ERC (Electrical Rules Checker). To avoid false errors about power sources, I added PWR_FLAG symbols to the 3.3V and GND nets, telling KiCad that the XIAO acts as our power source.

Physical Routing

In the PCB editor, the design becomes physical. I had to make strategic decisions regarding the layers and track widths:

Track Widths: I used a standard 0.25mm width for data signals (like the button and IMU data), but increased the width to 0.5mm for power lines (3.3V and GND) to ensure stable current flow.
Layers: I routed the copper traces on the F.Cu (Front Copper) layer.
Edge Cuts: Finally, I used the Edge.Cuts layer to draw the custom board outline, giving the PCB the shape of my dog! 🐾

KiCad Shortcuts (Cheatsheet)

To work faster and more efficiently in KiCad, mastering keyboard shortcuts is essential. Here are the most useful commands I constantly used during my circuit design process:

Key	Action	Environment
`A`	Add a symbol / Add a footprint	Schematic & PCB
`M`	Move an item (disconnects wires)	Schematic & PCB
`G`	Grab / Drag an item (keeps wires connected)	Schematic & PCB
`R`	Rotate an item 90 degrees	Schematic & PCB
`W`	Draw a Wire	Schematic
`L`	Add a Net Label	Schematic
`P`	Add Power symbol (VCC, GND)	Schematic
`E` / `V`	Edit properties / Edit Value	Schematic
`X`	Route a track (Draw copper line)	PCB layout
`Del`	Delete selected item	Schematic & PCB

KiCad Guide: Dog Wearable

XIAO RP2040 + MPU-6050 · Step-by-step from scratch

Phase 1 — Setup

01. Install KiCad

Download and install KiCad 7 or later on your computer (Windows, Mac or Linux).

✓
Install with all default libraries
✓
Open the Project Manager to start

Tip: Always use the latest stable version for better compatibility.

02. Create a new project

Organize your files from the start to keep the schematic and PCB linked.

Go to:

File → New Project

✓
Name it dog_wearable
✓
Keeps .kicad_sch and .kicad_pcb together

03. Manage Libraries

Add specific footprints or symbols that aren't in the default KiCad library.

Path:

Preferences → Manage Symbol Libraries

1
Click the folder icon to add .kicad_sym
2
Repeat in "Manage Footprint Libraries"

Phase 2 — Schematic

01. Add XIAO RP2040

Place the main microcontroller on the schematic canvas.

A
Press A to open symbol browser
🔍
Search for "XIAO RP2040"

02. Add the MPU-6050

Add the motion sensor to the schematic, leaving space for wires.

Library:

Sensor_Motion

03. UI Components

Add the button, LED, and required resistors using the browser (A).

1
SW_Push
2
LED

04. Power Symbols

Connect power cleanly using PWR and GND symbols.

P
Press P for power menu
🚩
Add PWR_FLAG

05. Use Net Labels

Instead of drawing long wires, use labels for a clean schematic.

Shortcut:

Press 'L' to Label

06. All Connections Via Net Labels

After connecting everything, it dshould look like this.

07. Run ERC

Verify there are no logical errors in your schematic.

✓
Electrical Rules Checker

Bill of Materials & Pinout

This table describes the components used for the Dog Wearable PCB and their specific connections to the XIAO RP2040.

Component	Qty	Connection (XIAO)	Function
XIAO RP2040	1	Main Controller	The brain of the wearable.
MPU-6050	1	D4 (SDA) / D5 (SCL)	IMU Sensor for motion detection.
Push Button	1	D6 (Input)	User interface to trigger events.
Red LED	1	D10 (Output)	Visual status indicator.
Resistor 330Ω	1	In series with LED	Current limiter for the LED.
Resistor 10kΩ	1	Connected to D6	Pull-down resistor for the button.
Pin Headers	2	VCC / GND / Pins	To connect