This project started as a “quick build” and somehow turned into a full redesign loop I did not see coming.

I spent around 16 hours straight building it end to end. No breaks, just flow. Schematic → PCB → Fusion 360 enclosure. Everything was moving fast and honestly felt solid at the time.

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⚡ Schematic phase

Mapped out the full switch matrix. Rows and columns looked clean on paper. Nothing felt off. This was the calm stage.

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🧩 PCB design

Routed everything around the XIAO RP2040. Tight layout, all pins assigned, everything looked correct.

That’s the keyword: looked.

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🖼️ Fusion 360 enclosure

Built the case, aligned the board, checked fitment. At this point I genuinely thought:
“yeah, this is a first-try success.”

It wasn’t.

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💥 The moment it broke

During final checks, I realized something stupid but critical:

✔ Rows were connected
❌ Columns were NOT connected to the XIAO

At first I thought: “ok easy fix, PCB edit, done in 2 minutes.”

Then reality hit.

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🚫 The real problem

No GPIO pins left on the XIAO.

Zero. Everything was already assigned.

So the “quick fix” wasn’t possible at all.

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🔧 Forced redesign

Only option left was to free up pins.

That meant removing the potentiometer I had already designed into the system.

And that one change didn’t stay small:

~ PCB had to be updated again 🔁
~ Pin mapping had to be redone 🧠
~ Fusion enclosure had to be redesigned 🧱
~ Mechanical layout shifted again 📐

What should’ve been a tiny wiring fix turned into a full system rollback.