Status: Planning · Started: July 2026

Overview

I need a CW keyer. I don't want to buy one, but let's put together a relatively straightforward build using preexisting firmware.

The build-log posts on the blog will capture the build as it happens; this page holds the current (and at some point final) state of the design: references, open questions, decisions, and eventually schematics, board layouts, and test results.

References

• K3NG Arduino CW Keyer — source and documentation for the firmware
• Arduino Pro Micro — pinout and specifications for the board this build is based on
• 16x2 Character LCD — pinout and wiring for the HD44780-compatible display

Open Questions

• Use the Arduino Leonardo Micro I have on hand (and live without the CW practice mode) or find a different Arduino with more flash memory?
• Add a SPST for sidetone switch? Might be nice.
• Where should I put the key jack? I should think about the ergonomics of using the whole thing as a handheld with the N6ARA TinyPaddle. I planned it to be on the bottom-front, but I think it should be on bottom-right (I'm right-handed) and the cables should attach bottom-left, or perhaps off the back.
• Can I cram all this into the Altoids tin?

Decisions

• Use a 16x2 screen (vs no screen). Why not. I have one.
• Use a rotary encoder with button for CW speed and control mode. Kinda like the QMX.
• Three memory buttons (6x6x8)
• Two LEDs (command mode and key output down).
• Use Arduino as the power source.

Arduino Pinouts:

Schematics

(Not yet — will appear as design work starts.)

Board Layouts

(Not yet.)

Build Notes

(Not yet — module-by-module notes will go here, with links to the relevant build-log posts.)

Test Notes

(Not yet — bench checks, timing measurements, and on-air results.)