search

deckerego / Macropad_4chord_MIDI

A take on the 4chord MIDI project with the Adafruit Macropad
Mozilla Public License 2.0
47 stars 4 forks source link
adafruit circuitpython macropad midi midi-controller music-player music-theory neopixel rp2040

readme

Macropad 4chord MIDI

Macropad 4chord MIDI

Contents

About

"All the greatest hits from the past forty years just use four chords. Same four chords for every song. It's dead simple to write a pop hit." -- Benny, Axis of Awesome

A four-chord MIDI device that allows you to rapidly churn out catchy tunes. Set your root key & chord progression, then off you go. Includes drum pads so you can provide a backing beat to your tracks.

Huge thanks to so many who have inspired this idea, especially:

Would you like to learn more about music theory and music composition? May I recommend:

Playing

The Macropad 4chord MIDI is built to play simple chord progressions, follow scales to build melodies, and act as a drum kit as a MIDI device. You can connect the Macropad to any studio recording software or DAW accepts MIDI devices, such as GarageBand or Abelton Live.

The 4chord MIDI has five different modes: a "harmony" mode that allows you to select progressions and root keys to play chords, the "autochord" mode that lets you play an entire chord with a single key (like the sequencers of the 80's and 90's), a "melody" mode that highlights different scales you can play, a "rhythm" mode that allows you to use the MacroPad as an acoustic drum / electric drum / percussion pad, and the "MIDI controls" mode that lets you set MIDI command controls (including note velocity). You can switch between each mode by clicking on the rotary dial.

There are a few quick demos showing how to use the MacroPad 4chord MIDI in a DAW:

Switching between triad, autochord, melody, drum pad, and MIDI settings modes

Chord Keyboard (Triad Mode)

Once you power on the Macropad a default progression is loaded into "Triad Mode", with the root on middle C (I'm a assuming middle C is on the third octave). The root note is at the top left, with the major (or minor) third and perfect fifth on the middle and right keys. The key and octave can be changed by rotating the encoder dial, going up or down the chromatic scale.

As you go down the keypad, the notes follow the four chord progression listed on the screen. By default this is a I-V-vi-IV progression, so with the root at C3 you will have G3, A3, and F3 as you go down the keypad. You can rotate through some four chord progressions by pressing down on the encoder button while rotating the dial.

Thanks to the RP2040, all the keys can be pressed simultaneously. You can play the triad chords for each degree, or arpeggiate the chords however you like. The list of notes currently being played are displayed on screen if you want to check my math.

You can bend the current notes being played by rotating the dial while keys are being held down. Rotating counter-clockwise will bend the pitch down, rotating clockwise will bend the pitch up.

AutoChord Mode

Clicking once on the rotary dial after the Macropad boots loads the "AutoChord" mode. In this mode each button does not correspond to a note, instead each button corresponds to a chord.

This mode does load a chord progression just as the previous "Triad Mode" does, however each combination of keys you press in a row corresponds to a different type of cord. The map is:

Key 1 Key 2 Key 3 Chord Type
Press Major Chord
Press Minor Chord
Press Dominant 7th Chord
Press Press Major 7th Chord
Press Press Minor 7th Chord
Press Press Diminshed Chord
Press Press Press Augmented Chord

Each chord also has an accompanying bass chord, where the 1st and 5th one octave lower are played alongside the chord. This can be configured to be just the root, or the 3rd, or disabled entirely in settings.py.

AutoChord mode also allows you to arpeggiate chords, so that there is a slight delay between each note as it is played. This works well with guitar voices, since it provides a more realistic strum-like effect. This can be configured within the MIDI Controls configuration screen, and defaults can be configured within settings.py.

Highlight Scales (Melody Mode)

Clicking again on the rotary dial brings up a keyboard where a selected scale is highlighted on the keypad so you can type out a melody. Each of the 12 buttons on the Macropad will correspond to a note on the chromatic scale, with the root note you have selected in the top left.

The buttons that are illuminated correspond to the scale selected while in this mode. You can play as many notes as you wish simultaneously, however only the highlighted notes are part of the selected scale. To change to a different scale (pentatonic major, relative minor, blues major, etc.) press down on the encoder button and rotate the dial. The name and first seven notes of the scale will be shown on the display.

Just as when playing chord progressions, you can bend the current notes being played by rotating the dial while keys are being held down. Rotating counter-clockwise will bend the pitch down, rotating clockwise will bend the pitch up.

Drum Pads

If you click three times on the rotary dial after the Macropad boots, it will move into the drum pad mode. Rotating the dial will allow you to select from a number of drum or percussion presets where MIDI notes match an acoustic drum, a rhythm composer (such as the classic TR-808), or percussion strikes. Actual percussion sounds depend on the MIDI controller or DAW you are using, so you may need to make some configuration tweaks with the MIDI mapping to match what instrument you want to use.

MIDI Controls

Clicking four times after booting the Macropad will take you into the MIDI controls mode, where you can adjust MIDI controls that are transferred to your DAW when recording. This includes global settings (such as attack or release time) as well as note settings (such as velocity). The AutoChord setting that allows you to arpeggiate a chord is also listed here.

Bear in mind that not all DAWs will register MIDI commands from devices in the same way. Some DAWs register the commands so long as your device is connected, others will not register any commands until you begin recording. If you find that your DAW isn't picking up the values you set, start recording while the "MIDI Controls" mode is showing on the Macropad, then single-click to return to the chords mode immediately after. This will re-send all the MIDI commands to your DAW.

Installing

First make sure that your Macropad has the latest version of CircuitPython 8.x installed. See https://learn.adafruit.com/adafruit-macropad-rp2040/circuitpython for instructions on how to update the Macropad to have the latest version of CircuitPython.

When installing the Macropad 4chord for the first time, extract the latest MacroPad 4chord MIDI.zip into a directory, then copy the contents of that extracted archive into the CIRCUITPY drive that appears when you plug in your Macropad. Ensure that the contents of the lib/ subdirectory are also copied - these are the precompiled Adafruit libraries that power the Macropad.

Updating

After you first install this version of Macropad 4chord MIDI and reboot, the Macropad will no longer mount as a removable drive. This ensures that Windows and MacOS won't complain if you unplug or reboot the device, making it behave more like pure MIDI device. This also helps mobile devices as well, as sometimes Android can't tell if the Macropad 4chord MIDI is a input device, a flash drive, or a MIDI keyboard.

To update or edit the code on the device, or to modify the settings, you first need to reboot the device with the Macropad's drive mounted in read/write mode. To do that, reboot the device using the boot switch on the left of the Macropad, and then after releasing the button immediately hold down the rotary encoder button. You should see the text "Enabling Updates" quickly appear on the screen, and then a removable drive will mount in read/write mode that contains some documentation and the Macropad's CircuitPython code.

Configuring

The settings.py file has several settings you can tweak, including MIDI note configurations, MIDI channel settings, and a list of the progressions you can scroll through. If you would like to add your own chord progressions or would like to keep a shorter list of possible keys, you can make those changes in the settings.py file within the CIRCUITPY drive. Just make sure to mount your Macropad in read/write mode (see Updating).

Building

There is no build process since the Python files are distributed in .py form and are not compiled to Micropython. All files are packaged as-is.

Packaging

The necessary Adafruit CircuitPython libraries are provided in the releases package but not included in the Git repository for obvious reasons. If you are installing from this repo directly, review lib/README.md for details on how to add the necessary libraries.

Unit Testing

Unit testing can be run with:

python3 -m unittest discover