Chirp

Consider this early alpha software for now.

Chirp is a Teensy 4.0 MIDI processing firmware with an on-device Wren runtime, USB control protocol, and flash-backed script/data storage.

Hardware

• MCU board: Teensy 4.0
• MIDI breakout used in this project: https://www.tindie.com/products/deftaudio/teensy-40-midi-breakout-board-5in-5out-usb/

Upstream Projects

• Wren language: https://wren.io/
• Wren source repo: https://github.com/wren-lang/wren
• Teensy platform: https://www.pjrc.com/teensy/
• Teensyduino / Arduino core package: https://www.pjrc.com/teensy/td_download.html

Toolchain And Libraries Used

From the current build configuration/logs:

• Arduino FQBN: teensy:avr:teensy40:usb=serialmidi
• Teensy platform/core: teensy:avr version 1.60.0
• Core variant: teensy4
• Libraries:
  • MIDI Library version 5.0.2
  • LittleFS version 1.0.0
  • SPI version 1.0

Repository Layout

• chirp/chirp.ino: Arduino sketch entrypoint
• src/: firmware components (MIDI router, USB protocol handlers, Wren bridge/host)
• src/include/: headers and protocol definitions
• tools/chirp_fs.py: host-side serial tool for managing files on device flash
• scripts/*.wren: user Wren scripts uploaded to /scripts/user on the device
• midi_maps/*.json: user data uploaded to /userdata on device flash
• third_party/wren-json/: JSON parser module for Wren

Build And Flash

From repo root:

make

Upload firmware (press Teensy button when prompted):

make upload

Upload scripts + maps to on-device flash:

make upload-fs

Full flow (build + upload + filesystem sync):

make upload-all

Python Host Tool Setup (tools/chirp_fs.py)

1) Install Python dependency

python3 -m venv .venv
source .venv/bin/activate
pip install pyserial

If you do not want a venv, install system/user-wide:

pip3 install --user pyserial

2) Verify serial device access

Default serial port is /dev/ttyACM0. If needed, pass -p.

./tools/chirp_fs.py -p /dev/ttyACM0 ping

3) Common commands

./tools/chirp_fs.py -p /dev/ttyACM0 list
./tools/chirp_fs.py -p /dev/ttyACM0 sync --delete scripts/ midi_maps/ third_party/wren-json/
./tools/chirp_fs.py -p /dev/ttyACM0 reboot
./tools/chirp_fs.py -p /dev/ttyACM0 monitor

Notes

• Device flash layout used by sync:
  • /scripts/user: user Wren scripts
  • /scripts/builtin: runtime/modules (e.g. json.wren)
  • /userdata: JSON maps and cached user data
• The D-Station script forwards translated CC to MIDI port 1, MIDI channel 10.