MIDI Chord Helper

[Auther's home (Japanese)] Chord-visualizable software MIDI keyboard implemented as Java applet/application [Japanese] [English]

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[Manual (Japanese)]

[Java source code]

[Musical Chord Instrument "CAmiDion" - MIDI Chord Helper Mobile]

Let's try !

MIDI Chord Helper screen shot (Click to enlarge) Software requirement: Sun Java2 VM
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Welcome to MIDI Chord Helper page ! You can play the music easily by clicking chord symbols on this software, and can find out chord diagram for keyboard, ukulele, and guitar.

The chord buttons are placed by order of the Circle of Fifths, and four background colors which indicates the feeling ( Pink:Local, Yellow:Hot, Blue:Cool, Green:Remote ) can be shifted by clicking key signature button, so you can understand key & chord's relationship visually and easily.

MIDI recording/editing/playing, connecting to external MIDI IN/OUT devices also available with this software.

You can enjoy and learn about music chord progression by watching the shapes (+, square, circle etc.) appered on the chord buttons.

If you created new MIDI file, please try to play it on this software. and you can find mismatch between meta-event (key signature, time signature, tempo, lyric etc) and other event (notes, chords, and its timing, etc).

Note: Some extended chords / added chords (-9/+9/11/13 etc.) are not supported. Supported chords are: X9, Xadd9, X69, XM9 etc.

Demo video

Song : Innocence / KazuP feat. Hatsune Miku

CAmiDion - MIDI Chord Helper Mobile

Original musical chord instrument, with accordion-like chord C, Am button placed vertically, and with MIDI interface, Kamide(Auther's name)-on(Kanji pronounciation which mean "sound")


I implemented the MIDI Chord Helper software's chord button as hardware, electronic musical instrument "CAmiDion".

In May 2009, I visit Make:Tokyo Meeting 03 held in Tama-Center, and purchaced "Arduino Wo Hajimeyo Kit" (= beginner's kit) which includes Arduino Duemilanove. Then, the first version of CAmiDion was implemented using the Arduino Duemilanove and two YMZ294 square-wave chips to support 3x2=6 polyphonic sound. This instrument was exhibited first in Niconico Gijutsu-bu (= technology group of Niconico Douga users) exhibition and presentation event held in Kawasaki (a city between Yokohama and Tokyo), Aug 2009.

Subsequently, I altered to newer CAmiDion many time, to exhibit on Make:Tokyo Meeting 04/05/06/07 (in Tokyo Institute of Technology Ookayama campus), Maker Faire Tokyo 2012/2013 (in Kagaku-Miraikan, Odaiba-area), and some other exhibition/presentation events (full list is here).

The newest (in 2014) CAmiDion has software-implemented sound synthesizer, which supports ADSR envelope, wavetable-based 6 polyphonic sound (sine/square/sawtooth/triangle/sine-shepard-tone/noise waves), so external sound chip not required. Audio output is simply CR low-pass filtered PWM. Controlled and sounded by ATMEGA328P (same chip as Arduino Duemilanove).

Until Apr. 2014, I implemented CAmiDions on universal circuit board with hand-wiring. After that, I designed CAmiDion's PCB (printed circuit board) with KiCad, ordered to PCB manufactureing service, and implemented CAmiDion with the PCB.

CAmiDion movies on YouTube

For more information - CAmiDion's home page (Japanese) / OSDN CAmiDion Wiki

Sample playing

Pomp and Circumstance

Chord mode

Sounding a chord per a button, with chord symbol display

Single-note mode

Sounding a root note of the chord only, per a button

MIDI Chord Helper - since May 2004
Copyright (C) 2004-2019 Akiyoshi Kamide