Standalone Keyboard LED Indicator
This project is a custom-built external LED indicator for keyboard lock keys — Caps Lock, Num Lock, and Scroll Lock. The idea came from a simple problem: my mechanical keyboard doesn’t have any built-in indicator lights for these functions. Rather than replace the keyboard, I set out to create a dedicated external device that could display their status at a glance.
While the software side was relatively straightforward, the real focus of this project is on product design, hardware, and electronics. The indicator is powered by a microcontroller with native USB HID support (ATmega32U4), allowing it to appear to the computer as a keyboard and read lock key states directly from the host.
The final design will feature:
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A compact enclosure, custom-designed and potentially CNC-machined
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A purpose-built PCB for clean wiring and durability
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Clearly visible LEDs for each lock function
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A true plug-and-play experience on modern operating systems
This project blends practical utility with custom hardware design, producing a device tailored exactly to my needs.
Caps Lock Indicator Prototype Success
Today I tested the prototype Caps Lock indicator code on an Arduino Leonardo I had lying around, and it worked exactly as intended. The LED on pin 7 lights up only when Caps Lock is active on the host computer — a small but satisfying milestone.
One key takeaway from this test: for the device to be truly plug-and-play, we need microcontrollers that use the ATmega32U4 (or similar) chip. This is important because the ATmega32U4 can act as a native USB HID device (Human Interface Device), meaning it can directly emulate a keyboard and read Caps Lock state from the host. Many other Arduino boards (e.g., Uno with ATmega328P) can’t do this without extra hardware, so they’re out of the running for this project.
For the final version, I’ll be switching to an Arduino Micro, which also uses the ATmega32U4 but is more compact and better suited for a finished product.
With the core functionality now proven, the next steps are all on the hardware side:
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Designing the housing
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Possibly CNC machining the enclosure for a clean fit and finish
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Designing a PCB to keep wiring tidy and robust
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Assembling everything into a single cohesive unit
Still plenty of work ahead, but this test validates the fundamental approach and gives me a solid foundation to build on.
