low-profile hexagon keyboards.

input/output (midi, i2c)

The 0x33.board supports both USB MIDI and TRS MIDI. The TRS MIDI port is output only. The channel to use for both protocols can be set individually on the MIDI page of the settings screen. The velocity of the sent MIDI notes can be set as well.


The 0x33.board output jack uses the standard Type-A TRS jack assignment for the TRS MIDI output. When connecting to equipment with a 5-pin DIN port, a matching Type-A adapter cable must be used. Other equipment that has a Type-A port can be connected using a regular TRS (stereo) audio cable.

Older MIDI devices by other manufacturers may have a Type-B TRS MIDI jack and corresponding adapter cables. These adapter cables won’t work with the 0x33.board in its stock configuration, and a TRS cable cannot be used to connect them directly to the 0x33.board. Instead, you could use a Type-A and a Type-B connector to join the two devices.

Type-B conversion

If you have a lot of Type-B equipment and matching cables, you can convert the 0x33.board to a Type-B output. Be aware however that Type-B ports are non-standard and most manufacturers that used them have switched to the official Type-A port, so Type-B equipment will probably fade out in the near future.

To do the modification you need a box cutter or scalpel, a soldering iron and some solder. The modification can be reversed just as easily.

  1. Make sure the 0x33.board is not connected to power.
  2. Remove the two screws holding it in place and take off cover from the top of the 0x33.board.
  3. Locate the MIDI jack and the solder jumpers labelled “Type-A” and “Type-B” respectively near the middle of the newly exposed part of the circuit board:

    By default, the left and middle pad of both the top and bottom jumper are connected by a little trace. If this connection as removed and the middle and right jumper are connected instead, the output becomes a Type-B port.

  4. Using a box cutter or scalpel, carefully cut away the connection between the left and middle pad of each jumper respectively. The cuts should end up where the red lines are in the diagram above.

    Make sure that the copper trace under the colored soldermask is completely severed and the two sides don’t touch anymore. You may need to cut or scrape repeatedly at different angles to carve a little channel.

  5. Using the soldering iron add a little bit of solder to bridge the middle and right pads of each jumper, marked in purple in the diagram above.

To reverse the conversion, use a soldering iron to move the bridge from the right to the left side of each jumper. If you have a desoldering pump or solder wick that can be used to remove the solder from the side you want to open, but If you don’t you should still be able to shove the solder around using the tip of the iron once it’s melted.


I2C support is a work in progress.

external devices

If you have [access to] other equipment that supports i2c connections and would like to help make them supported, please reach out via email.

multiple 0x33.boards

If one or more boards are put into “follower” mode and set to use different i2c addresses on the i2c settings page, a board put into “leader” mode will recognize them and connect automatically when entering that mode.

To re-scan for new i2c devices, disable and re-enable “leader” mode. Currently only note-on and note-off events are synchronized, but a mechanism to synchronize the active scale, layout, and lighting settings is planned.