MIDI8d – 8 Digital Outputs

Description

The MIDI8d is a 4HP wide, simple and versatile Eurorack module that can output 8 digital gate or clock signals from a single MIDI TRS input connection.

If you also need analog CV outputs, have a look at the MIDI8d+.

Firmware

The core of the MIDI8d is a classic Arduino Nano (ATmega328p), programmable with the free Arduino IDE. Different firmware sketches can be uploaded to adapt or completely change the module’s behaviour.

Firmwares are cross-compatible between MIDI8d and MIDI8d+.

Typical uses:

• 8 drum trigger outputs, reacting to MIDI Channel 10 (notes 36 to 43)
• MIDI Clock with various time divisions and Start/Stop Gate outputs
• MIDI channel activity monitor
• … and many more: write your own!

Open source firmware repository: https://github.com/dhaillant/midi8d/

Hardware

The module consists of two PCBs:

• the Front PCB, supporting all jack connectors and LEDs
• the Rear PCB, supporting the Arduino Nano and the Eurorack power input

The MIDI input jack is a stereo TRS Type A connector (Tip = Sink, Ring = Source). The MIDI input circuit is built around the high-speed optocoupler 6N137.

Many components are in Surface Mount Technology (SMT). Check out the pre-assembled SMD option, with this option, the only remaining components to solder are classic Through Hole parts, making the build very accessible.

Documentation & resources

• Full documentation & schematics: https://www.davidhaillant.com/midi8d-8-digital-outputs/
• Interactive BOM: available on the documentation page above
• Source code & firmware wiki: https://github.com/dhaillant/midi8d/