I2c2midi – A DIY Module That Translates I2C To MIDI - Tech

I’m a big fan of Teletype and the I2C protocol. Lately, I have been experimenting with the idea of using I2C to control external devices outside of the Eurorack case. Here’s a little prototype module that I’ve built – and which I would like to share with you.

There are two reasons for me to post it here on lines:

First – Maybe someone else finds this module helpful and would like to build it or modify it. The schematic, BOM, firmware code and more details are all in the Github Repo.

Second – I am definitely no expert in electronics nor circuitry design … But I’m sure some of you here in this great community are! So I’m very much looking for input on how to improve it or even correct some mistakes I made. Ideas, recommendations and tips are greatly appreciated and I am happy about everyone who wants to contribute.

Thanks!

i2c2midi

i2c2midi is a simple DIY 3 hp eurorack module that speaks I2C and MIDI. It’s primarily build to be used together with monome Teletype. It receives I2C messages from Teletype and converts them to either MIDI notes or MIDI CC messages to control external devices like synths and effects.

Currently in prototype status: The first prototype was built using a horizontal protoboard and a LEGO 2x16 plate as front panel.

Todo: Create a PCB and proper front panel.

i2c2midi_diagram1680×728 15.5 KB

Details

• DIY eurorack module (prototype)
• 3 hp (LEGO front panel)
• Inputs: I2C
• Outputs: 1 x MIDI TRS (Type A)
• Based on Teensy 3.2

i2c2midi_top1800×1200 292 KB

i2c2midi_side1800×1200 166 KB

Usage

The firmware is written specifically for I2C messages sent from Teletype using the disting Ex MIDI OPs by scanner-darkly. The module “poses” as a second disting.

Send MIDI notes

EX 2 EX.M.CH channel EX.M.N note velocity

Send MIDI CCs

EX 2 EX.M.CH channel EX.M.N controller value

Note off messages

The firmware takes care of Note off messages automatically, but is currently monophonic per channel. Note off messages are sent when a new Note on message arrives or after 500 ms.

Todo: Make the note duration of 500 ms editable via I2C as well. Todo: Make it handle polyphony.

Example

I am using the module together with a MIDI splitter, having Elektron Analog Four on channels 1-4, Nord Lead on channels 5-8, and OTO Bim and Bam on channels 15 and 16. Here’s an example patch, sending MIDI notes and CCs to Elektron Analog Four and Nord Lead from Teletype: A̵ ̷T̶T̵~0̷ ̶V̵V̷ ̷A̷ ̴T̸ ̴T̷ on Instagram: "R A N D O M - C H A N N E L - 1 / / Elektron Analog Four and Nord Lead playing together, sequenced by Teletype via I2C→MIDI. Each note of the sequence is randomly sent to either the A4 or the Nord Lead. Additional modulation of their filter frequency via MIDI CCs. Mangrove for Bass, Plaits for supersaw pad, DistingEx in multisample mode for piano (all three sequenced from TT, too). Batumi for additional modulation. Oto Bam for space. / / #jamuary2021 #eurorack #modularsynth #eurorackmodular #synthesizer #synths #monome #teletype #mutableinstruments #expertsleepers #distingex #I2C #I2C2MIDI #elektron #analogfour #nordlead #otobam" The main script is:

EX 2 // following code is for the "second" disting EX.M.CH + 1 * 4 TOSS // select A4 or Nord Lead randomly EX.M.N PN.NEXT 0 127 // send a note EX.M.CH 5 // select Nord Lead EX.M.CC 74 RRND 50 127 // control Filter Frequency via CC

Github Repo

GitHub - attowatt/i2c2midi: i2c2midi is a DIY open source 2 HP Teletype...

i2c2midi is a DIY open source 2 HP Teletype Expander that speaks I2C and MIDI. - GitHub - attowatt/i2c2midi: i2c2midi is a DIY open source 2 HP Teletype Expander that speaks I2C and MIDI.