WIP

I haven't really worked out the sequencer fully. I think I know how I want it to work, but haven't written the code to make it work that way. I think the lib is still useful as it is, to make things (I have all the known sysex commands worked out, etc) but it will need some more work to be a functional sequencer.

BeatStep Interceptor

This is a command-line program to make the Arturia BeatStep work in different ways than the firmware is meant to.

The Arturia BeatStep is a really nice-feeling device, that is pretty cheap (~$100 new.) The built-in firmware for the device is OK, but a bit wonky for sequencing complex drum-patterns. Since I don't have access to the firmware's source, I made this so I'd have a sequencer that works how I want.

It starts a virtual midi device that can be plugged into other software.

IMPORTANT Using the sequencer will set your device up with specifc mappings and stuff, so make sure to back up your beatstep settings in the MIDI Control Center (from Arturia) program, or use STORE/RECALL buttons on device, or use save/load in CLI, if you care about them.

installation

npm i -g beatstep

You can also run it without installing:

npx beatstep list

usage

command-line

beatstep <command>

Commands:
  beatstep load <file>  Load a .beatstep preset file
  beatstep save <file>  Save a .beatstep preset file
  beatstep list         List MIDI devices
  beatstep seq          Start sequencer

Options:
  --help     Show help                                                 [boolean]
  --version  Show version number                                       [boolean]

Commands have more options. If you want to know more about it, run beatstep <command> --help

interaction

I am still working on this part. Here is how it currently works:

• run beatstep seq to start the sequencer
• Make sure controller is in CNTRL mode (red) and turn on EXT SYNC (blue)
• Press SHIFT to chose pattern
• Press STOP to choose track
• PLAY will play/stop the current pattern

The notes it sends out are based on hydrogen drumkits, which is a common mapping for drumkit-instruments starting at C1 with a kick drum. Eventually, I can make this a configurable option (like a CLI flag that you can tell it the notes it can use for each track.)

as a library

You can also use this as a nice BeatStep interface, in your own code

The class constructor has 2 params, which are the names of input and output device (you can get with require('easymidi').getInputs() and require('easymidi').getOutputs().)

import { getOutputs, getInputs } from 'easymidi'
import { BeatStep } from 'beatstep`

const beatstep = new BeatStep(
  getInputs().find(d => d.includes('Arturia BeatStep')),
  getOutputs().find(d => d.includes('Arturia BeatStep'))
)

beatstep.on('noteon', console.log)
beatstep.on('noteoff', console.log)

hardware

Eventually, I'd like to reprogram the chip on the controller to acheive a fully custom standalone sequencer.

It uses a stm32f103 chip, with some supporting circuitry to multiplex all the buttons, leds, and knobs. It looks like they are using hc574 to multiplex rotoary-encoders, somehow. It looks like it has programming pins on board (JP1) but firmware updates over sysex would be preferrable. This might give me some ideas for reversing the firmware to the point that I can read inputs, output LEDs, and eventually just write my own interface.

Ideally, I could compile my own code, create my own led file (appears to be hex) and send over sysex.

TODO

• Fill in the docs: api & docs.
• Figure out RATE knob for BPM
• Figure out CHAN so I can use that to switch tracks and use SHIFT to do something else (commands like copy/paste and sequencer controls would be cool)
• Use STORE/RECALL for something other than intended. Would be good to fire save/load (maybe combined with SHIFT and STOP for track/pattern/song)
• Figure out easier-to-compile MIDI lib (for cross-platform release building)
• Different seqquencer styles: current (all drums in one instrument on one channel), seperate drum instruments, seperate channels, something for melodies
• Better debug more that prints all midi messages sent and received

thanks

I couldn't have made this without the awesome hacking in this blog post.