Morse Code keyer and visualizer.

Supported keyer modes: Iambic A, Iambic B, Ultimatic and Straight.

keyer is a state machine program. It receives events from stdin and produces events to stdout.

Input events (4):

dit down, dit up, dah down, dah up

which basically indicates if the dit/dah paddle is pressed.

Output events (10):

• dit down/dit up/dah down/dah up: just echoes of stdin
• dit, dah: a dit/dah is recognized
• key on, key off: output key (tone) starts/stops
• char, word: indicates the boundary of a character/word

The visualizer GUI subproject receives stdin events:

• dit down, dit up, dah down, dah up
• key on, key off

and draws a representation of the dit/dah/tone lanes in realtime to demonstrate the timing.

cargo build && cargo build --manifest-path=visualizer/Cargo.toml 

Some interesting things can be done with programs above and these Python scripts altogether.

• audio-out.py: play tones according to key on and key off from stdin
• gamepad-pipe.py: map two buttons of my gamepad to these four paddle events ((dit|dah) (down|up))
• interface/read-serial.py: read bytes sent from an ESP8266 chipboard, from /dev/ttyUSBx, and map them to these four paddle events

I literally grabbed a $1.5 ESP8266 and made it the keyer interface.

So first, grab an ESP8266, and program it:

arduino-cli compile --fqbn esp8266:esp8266:nodemcuv2 interface
arduino-cli upload -p /dev/ttyUSB0 --fqbn esp8266:esp8266:nodemcuv2 interface

Then set things up like this:

Pins and mappings:

• D1 low: dit down - 0x01
• D1 high: dit up - 0x02
• D2 low: dah down - 0x03
• D2 high: dah up - 0x04

Corresponding byte will be sent to the serial @ 115200 baud. Read them using interface/read-serial.py.

(There's also a *nix-specific C implementation of read-serial. From my experience there's no difference with regard to latency.)

Combine things together:

interface/read-serial.py | target/debug/keyer -m ultimatic -w25 | pee ./audio-out.py visualizer/target/debug/visualizer ./decoder-wtype.py

Demonstration:

Note the ./decoder-wtype.py is optional. It receives dit, dah, char, word events and decodes them, and use wtype to type on Wayland.

Similar to above:

./gamepad-pipe.py | target/debug/keyer -m ultimatic -w25 | pee ./audio-out.py visualizer/target/debug/visualizer ./decoder-wtype.py

Demonstration:

See the android directory.

Demonstration:

(Audio latency happens here because it's that the screen recorder sucks but not the app has the issue.)

I use this as a software-defined Morse keyer solution. Stuff is mostly vibe coded with OpenCode:deepseek-v4-pro - fair warning. The README however, is written by me all by-hand :).

The project is inspired by https://www.youtube.com/watch?v=Hn4j2nfdKNE and their https://didahdit.com website.