CW Dojo

A Morse code (CW) trainer designed for the R36S handheld game console running ROCKNIX. Built with Python and pygame.

Learn CW the way you'd learn a language — through drills, listening, and practice on a device that fits in your pocket.

Screenshots

Main Menu	Koch Trainer	Band Explorer
Straight Key	Glossary

Features

Straight Key — Practice sending with the A button as a straight key. Hear your sidetone, see your dits and dahs decoded in real time.

Iambic Keyer — Plug in a CW paddle via the 3.5mm jack (or use L1/R1 on the gamepad) for iambic A/B keying with adjustable speed.

Koch Trainer — Receive practice using the Koch method with spaced repetition. Characters you struggle with appear more often. Toggle hints (D-pad Up) to see dit/dah patterns while learning. Progress persists between sessions.

Band Explorer — Simulated HF waterfall display. Tune across a 40m CW band segment with D-pad, hear stations calling CQ and having QSOs. Realistic band noise with atmospheric fading and static.

Vocabulary Quiz — Timed drills on common CW abbreviations and Q-codes. Listen to a CW phrase, pick the correct meaning.

QSO Procedure Trainer — Practice full QSO exchanges: CQ calls, signal reports, and common ragchew elements. Hear the expected exchange, then key your response.

Glossary — Browse common CW abbreviations, prosigns, Q-codes, and typical QSO phrases. Press R1 to hear any term played as CW.

Profiles — Multiple user profiles so you can share the device. Each profile tracks its own Koch progress independently.

Settings — Adjust sidetone frequency, character speed (WPM), Farnsworth spacing, master volume, and key sound style.

Controls (R36S)

Button	Function
D-pad	Navigate menus, tune waterfall, adjust WPM
A	Confirm, straight key, start round
B	Answer choice (Koch)
X	Answer choice (Koch), delete (callsign editor)
Y	Answer choice (Koch), edit callsign
L1/R1	Iambic paddle (dit/dah), play/hear audio
L2	Take screenshot
Select	Back to menu
Select+Start	Quit to EmulationStation

Controls (Desktop/Keyboard)

Key	Function
Arrow keys	D-pad equivalent
Space	Straight key
W/D/S/A	X/A/B/Y face buttons
R	Replay / play audio
H	Toggle hints (Koch)
F12	Take screenshot
Escape	Back to menu
Q	Quit

Requirements

• Python 3.10+
• pygame (or pygame-ce) >= 2.5
• numpy >= 1.24

Running on Desktop (Development)

git clone https://github.com/DavidClawson/cw-dojo.git
cd cw-dojo

With uv:

uv run python main.py

With pip:

pip install -r requirements.txt
python main.py

Installing on R36S (ROCKNIX)

Prerequisites

• R36S running ROCKNIX
• WiFi dongle connected and configured
• SSH access to the device

Install Steps

1. Install Python packages on the device:

   # From your computer, download aarch64 wheels
   pip download --only-binary=:all: --platform manylinux2014_aarch64 \
     --python-version 3.11 --implementation cp pygame numpy -d /tmp/wheels/
   
   # Copy to device
   scp /tmp/wheels/*.whl root@<device-ip>:/tmp/
   
   # SSH in and install
   ssh root@<device-ip>
   mkdir -p /storage/lib/python3.11/site-packages
   cd /tmp
   python3 -c "
   import zipfile
   site = '/storage/lib/python3.11/site-packages'
   for whl in ['pygame-*.whl', 'numpy-*.whl']:
       import glob
       for f in glob.glob(whl):
           print(f'Installing {f}...')
           zipfile.ZipFile(f).extractall(site)
   "

   Then symlink system SDL2 over the bundled versions (ROCKNIX's SDL2 has the correct display drivers):

   cd /storage/lib/python3.11/site-packages/pygame.libs/
   ln -sf /usr/lib/libSDL2-2.0.so.0 libSDL2-*.so.*
   ln -sf /usr/lib/libSDL2_image-2.0.so.0 libSDL2_image-*.so.*
   ln -sf /usr/lib/libSDL2_mixer-2.0.so.0 libSDL2_mixer-*.so.*
   ln -sf /usr/lib/libSDL2_ttf-2.0.so.0 libSDL2_ttf-*.so.*

2. Copy CW Dojo to the device:

   scp -r cw-dojo/ root@<device-ip>:/storage/roms/ports/morse_trainer/

3. Create the launch script:

   ssh root@<device-ip>
   cat > '/storage/roms/ports/CW Dojo.sh' << 'EOF'
   #!/bin/bash
   . /etc/profile
   export PYTHONPATH=/storage/lib/python3.11/site-packages
   cd /storage/roms/ports/morse_trainer
   python3 main.py > /tmp/cwdojo.log 2>&1
   EOF
   chmod +x '/storage/roms/ports/CW Dojo.sh'

4. Restart EmulationStation — CW Dojo will appear under Ports.

Project Structure

cw-dojo/
  main.py         Entry point and scene dispatcher
  audio.py        Sidetone and CW character playback (numpy + pygame)
  band.py         Simulated HF band with CW stations
  buttons.py      R36S button mapping constants
  glossary.py     CW abbreviations, Q-codes, and prosigns
  keyer.py        Iambic keyer logic (Mode A/B)
  koch.py         Koch method trainer with spaced repetition
  morse.py        Morse code table, decoder, and Koch character order
  profiles.py     Multi-user profile management
  progress.py     Persistent Koch training progress
  qso_scripts.py  QSO exchange templates and scripts
  scenes.py       All scene classes (menu, straight key, Koch, etc.)
  settings.py     Persistent user settings
  sounds.py       UI sound effects
  ui.py           Display rendering for all screens
  vocab_quiz.py   Vocabulary quiz scene
  waterfall.py    Waterfall display and band explorer scene
  assets/         Fonts, background images, and sound effects

PortMaster Package

The portmaster/ directory contains a standalone build of CW Dojo packaged for PortMaster. This copy is currently behind the main source and needs to be rebuilt from the latest code. A GitHub Action to automate this is planned.

Hardware

What You Need

To run CW Dojo on an R36S, you'll need:

Item	Notes
R36S handheld	The RK3326 model running ROCKNIX. ~$35 on Amazon.
USB WiFi dongle	Required for SSH deploy and future features. Must be Linux-compatible — the TP-Link TL-WN725N works well with ROCKNIX.
CW paddle or straight key (optional)	Any paddle/key with a 3.5mm TRS plug, or use a 3.5mm cable to wire your own.
3.5mm TRS audio cable (optional)	For connecting a CW key to the hardware mod.

Hardware Mod — 3.5mm Paddle Jack

A 3.5mm stereo jack (PJ-307) can be wired to the L1/R1 shoulder button pads to accept a CW straight key or iambic paddle. When nothing is plugged in, the shoulder buttons work normally (the jack's internal switches are normally closed). When a key is plugged in, the switches open and the key contacts take over. The keyer.py module handles iambic timing and mode switching.

Third-Party Assets

• Noto Sans (assets/NotoSans.ttf) — Google's Noto Sans font, licensed under the SIL Open Font License 1.1.

License

MIT — see LICENSE for details.

Contributing

Issues and pull requests welcome. This project is in early development — feedback from CW operators is especially appreciated.

If you're adapting CW Dojo for a different handheld or Linux device, the main things to change are buttons.py (button mappings) and the display resolution in main.py.

Support

If CW Dojo helped you learn CW or you just think it's cool, consider sponsoring the project on GitHub. It helps keep development going.

73 de CW Dojo