Electronics Design

Group Assignment - Multimeter Test

For this assignment, I worked with Mckinnon Collins, Max Negrin, and Oliver Abbot to utilize lab equipment to test embedded microcontrollers. The full group documentation can be found here.

A Multimeter is a diagnostic tool used in engineering to measure key electrical properties in a circuit, including voltage (V), current (A), and resistance (Ω). Its purpose is to verify circuit operation, troubleshoot issues, and ensure components are functioning within safe limits. Voltage is measured in parallel across components, current is measured in series with the circuit path, and resistance is measured by testing how much a component opposes electrical flow. Many digital multimeters also include continuity and diode testing modes, making them essential tools for analyzing, debugging, and validating electronic systems.

Resistor Testing

The first test I conducted with the multimeter was a resistance test on a resistor. To do so, I utilized the ohm setting on my multimeter and pressed the probes against my resistor. The resistor ended up having a resistance of 384.8 ohms, a number very similar to its 383 ohm label. This tells me that the resistor is functioning and can be used in a circuit.

Voltage Testing

The second test I conducted with the multimeter was a voltage test on my XIAO RP2040. Since the microcontroller has both a 5V pin and a 3.3V pin, I wanted to see if it actually produced that much power. To conduct the test, I first plugged my XIAO RP2040 into a power source and switched my multimeter to the voltage setting (the one that say V, not mV). I then placed the black multimeter probe on the GND pin and the red probe on the 5V pin. The multimeter returned a value of 5.147 volts.

I then did the same thing with the 3V pin by moving the red probe to the pin. It returned a value of 3.307 volts.

Both pins returned a value that approximately matches their corresponding label. This allowed me to confirm that the microcontroller's pins are functional and actually fulfill their supposed purpose.

Individual Assignment - Use an EDA Tool to Design a Circuit

To begin the individual assignment, I first wanted to create and test a real button circuit on a breadboard so that I would have a clear reference before moving into KiCAD. I used a XIAO RP2040, two tactile push buttons, one LED, and a resistor. Building it physically first helped me understand exactly how I wanted the circuit to behave before translating it into a schematic and PCB layout.

In this circuit, I programmed the buttons to control LED brightness. The left button (DOWN) decreases the LED brightness, and the right button (UP) increases the LED brightness. This gave me a simple but useful interaction model that I could directly map into my KiCAD design. By testing the behavior in real life first, I was able to confirm that my wiring and logic were working before I started designing traces and footprints.

Physical Button Circuit (Reference Build)

XIAO RP2040 Pinout Used in This Circuit

Function	Component Connection	XIAO RP2040 Pin
UP (right button) signal	Right tactile switch output	D8
UP (right button) ground	Right tactile switch ground	GND
DOWN (left button) signal	Left tactile switch output	D7
DOWN (left button) ground	Left tactile switch ground	GND
LED/resistor positive path	LED anode path through resistor	D9
LED/resistor negative path	LED cathode path	GND

With the physical circuit complete, the next step was to move into KiCAD and recreate this same wiring as a proper schematic and PCB design.

Moving Into KiCAD

KiCAD is an Electronic Design Automation (EDA) software suite used to design electronic circuits and printed circuit boards. It allows you to:

• create and organize circuit schematics,
• assign real component footprints,
• route copper traces in a PCB editor,
• check for electrical/design errors,
• and generate manufacturing outputs for fabrication.

For this assignment, KiCAD was important because it let me take my breadboard prototype and convert it into a manufacturable board layout. Instead of loose wires and temporary placement, KiCAD gives a permanent design that can be milled, soldered, and tested consistently.

Installing Libraries in Plugin and Content Manager

Before designing, I first opened KiCAD's Plugin and Content Manager to download the libraries and tools I needed. This step was very important because it made sure I had access to the exact symbols and footprints required for Fab Lab style components.

I downloaded the following packages:

• KiCad FabLib - this gave me footprints and schematics for components commonly used in Fab Lab inventories.
• Fabrication Toolkit - I installed this for future quality-of-life improvements in PCB workflow.
• Keyswitch KiCad Library - I installed this because I will need switch-related footprints for my final project design.

After installing those packages, I moved on to the schematic design process.

Building the Circuit in Schematic Editor

To start the schematic, I opened KiCAD's Schematic Editor and added the symbols for all required parts based on my real-life breadboard build. Specifically, I added:

• XIAO RP2040 microcontroller symbol,
• basic LED (diode),
• resistor,
• and two tactile button switches.

I then wired the schematic according to my tested physical circuit behavior:

• right button (UP) wired to D8 and GND,
• left button (DOWN) wired to D7 and GND,
• LED + resistor driven from D9 with return to GND.

This gave me a clean digital control structure where each button had a dedicated input pin and the LED output was isolated through the resistor.

Assigning Footprints Before PCB Layout

Before transferring the design into PCB Editor, I needed to assign the correct physical footprints to each schematic symbol using the Assign Footprints tab. This step is what maps abstract symbols (like a switch or resistor symbol) to real package dimensions that can actually be placed on a board.

The most difficult part of this step for me was finding the correct footprint for the tactile buttons. I had to search through the Omron tactile switch catalog and identify the exact model I was using. The switch turned out to be the B3F-40xx model, which in KiCAD mapped to:

Button_Switch_THT:SW_SPST_Omron_B3F-40xx

Once I found the correct switch footprint, the rest of the footprint assignments became much easier.

PCB Editor Layout and Routing

With the correct footprints assigned, I opened the schematic in PCB Editor and KiCAD automatically imported each component footprint. From there, I arranged all parts to match the intended flow of the circuit and then began routing traces according to the schematic connections.

I focused on keeping the board organized, both functionally and visually. I avoided unnecessary crossover paths, grouped related parts logically, and routed traces in a clean way so the board would be easier to understand and easier to mill/solder later.

3D Viewer Preview

Once routing was complete, I clicked the 3D Viewer button in KiCAD to inspect the final board in a realistic view. This step helped me verify footprint orientation, spacing, and overall board readability before fabrication.

Overall, this design process gave me a full workflow from breadboard prototype to PCB-ready file. It also prepared me directly for Week 8, where I would move from design into actually milling the board.