MIDI 8d+ – MIDI to 4 analog and 4 digital outputs

MIDI 8d+ is a very simple, yet super versatile MIDI-to-4-analog-and-4-digital-outputs module, that you can program and adapt to suit your needs.

It’s an upgrade from the previous MIDI8d module which is able to produce 8 digital outputs only (no analog outputs).
Compared to MIDI8d, the MIDI8d+ (note the PLUS) has the ability to produce 4 analog outputs in addition to 4 digital outputs.

These analog signals are generated by PWM and are filtered (low pass filter to attenuate the PWM noise) and buffered (the analog value doesn’t change upon load).


This is a very convenient, easy and inexpensive solution for adding Controls Voltages (CV) to your modular system.

However, PWM isn’t exactly perfect for sensitive and precise CV values (example, VCO tuning), but PWM is ok for anything else: CV for VCF frequency, CV for VCA, CV for delays, FM modulations etc. You can even produce audio signals.

MIDI8d+ front panel

The PWM outputs are identified with the “knockout” fonts.

MIDI8d+ V0.1 input/output chart

The first analog output (#5) has 16 bit resolution, while the 3 others (#6 to #8) are 8 bits.

The core of the module is a classic Arduino Nano (ATmega328p) and can be programmed with the free Arduino IDE. It’s inexpensive, easy to program and widely available. Also, many sketches and library are available across the Internet to download.

The module is 4 HP wide and in Eurorack format. +5V rail is generated on-board by the Arduino Nano.


About C7 and C10

C7 and C10 are 5mm diameter, 2mm pin-pitch, Through Hole, polarized capacitors. They’re not shown on some pictures here, but they are recommended as they help against potential ripple while LEDs are switched on/off.
The usual capacitance value is 10µF and the Voltage rating should be greater or equal to 25 volts.
Be careful when placing them. They are polarized: align the white marking on the PCB with the white band on the capacitors.

Documentation & downloads

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