exploratory_sysex_msgpack

A golang server and a jupyter notebook (okay, maybe 2 notebooks)

Server runs on Car Thing device, Jupyter notebook runs on pc

Rough data path:
encode json as msgpack -> encode custom TLV -> MIDI Sysex -> MIDI OUT -> MIDI IN -> identify Sysex -> decode TLV -> decode msgpack as json -> WS

Golang Server

Hosts Websocket Server that processes and sends the hw input events (buttons, knobs) and midi input to the car thing as ws messages

Jupyter Notebooks

midi_messages.ipynb

Contains test midi data to send to device input. Supports normal midi messages and custom sysex msgpack implementation

websocket_client.ipynb

Tiny notebook with separate websocket client to not deal with threading/asyncio/different client like postman

1. Prep to Cross-Build Golang Server:

1. Install Go
2. Clone/Download this repo and cd into it in a terninal
3. Set these Environment Variables for Go cross-building:
   • GOARCH=arm
   • GOOS=linux
   • Temporarily set env vars from terminal:
     • Powershell: >$env:GOARCH='arm'; $env:GOOS='linux'
     • Bash: >export GOARCH=arm && export GOOS=linux

2. Get dependencies and build arm binary

go get
go build .\main.go

3. Install python dependencies for jupyter notebooks

pip install -r requirements.txt (global install by default)

4. Set system read/write, push gadget script and binary to device

adb shell mount -o remount,rw /
adb push ./main /home/superbird/midi_hw_ws_server
adb push ./S49usbgadget /etc/init.d/

5. Allow execution for gadget script (IMPORTANT) and go binary

adb shell chmod +x /etc/init.d/S49usbgadget
adb shell chmod +x /home/superbird/midi_hw_ws_server

6. Reboot Car Thing

adb shell reboot

7. Start Golang Server

adb shell /home/superbird/midi_hw_ws_server

8. Start WS Client

ws://192.168.7.2:8080/ws

A ws client is provided in websocket_client.ipynb Alternatively, Postman is also simple to setup to listen for messages