MIDI Accordion (Diatonic Russian)   The MIDI Accordion encoder is capable of encoding the required momentary action, push to make, single pole single throw (SPST) switches to produce the equivalent MIDI note-on/note-off data commands. The design consists of the Miduino and the encoded switches wired via IN4148 diodes. The design is based on a  diatonic keyboard with 28 keys for the right hand and 20 keys for the left hand, but other keys could be encoded if required.       MIDI ACCORDION RUSSIAN ITEM#: MIDIACCRUSS PRICE:  €35.00     The MIDI Accordion Unit utilizes: The MIDI channel is set to channel 1 for right hand 28 switches, The MIDI channel is set to channel 2 for the Bass and  the associated Chord for left hand 19 switches, The velocity byte is preset to the maximum value. A Miduino kit including a suitable pre-programmed Atmega168, A 2.1mm power socket, and associated LED,  A MIDI 5-pin DIN input socket, A MIDI 5-pin DIN output socket, The circuit schematic is available, The switch wiring schematic        The MIDI Accordion Unit requires:   A 9v battery or equivalent DC power source Required 28+20+8 = 56 external switches and associated diodes

Circuit Schematic:

A circuit schematic of the Miduino  shows the switch connections. Note that for this project the 4-way DIL switch is not required. The circuit schematic for the wiring diagram is also available.

Assembly:

The kit includes all parts necessary, the assembly is straightforward and well documented. This design does not include a USB chip, it is designed to use a FTDI USB 232-TTL cable to program the microcontroller.  However since the cable plugs directly into the Miduino, you can use one cable for multiple Miduinos.

MIDI Wiring:

The MIDI IN and OUT connections use 5-Pin 180 degree DIN sockets. Note that the MIDI IN/OUT wiring is polarised and the correct pins should be used. 

MIDI Channels:

MIDI Accordion Switch Wiring:

The keys on the Accordion are wired to the midi switch encoder as shown below and in the switch circuit diagram. The switches are organized in a 8 x 6 matrix (48 switches) arrangement. 

Each of the other side of these switches SW0 to SW7 is wired to a diode on the Cathode (K) side (end of diode with stripe).

The other side of each of these diodes is looped to 5 other diodes. For example Anode (A) of diode DO is looped to D8 then to D16 then to D24 etc. down to D40 and finally to digital terminal D2 on the Miduino. The rest of the wiring is done in a similar manner.

The switches for the Octave shift are switches 48 to 51. The maximum Octave shift is +/- 2 Octaves. SW48 is +Octave Left, SW49 is -Octave Left, SW50 is +Octave Right and SW51 is -Octave Right. SW52 is + Octave Channel 3 only and SW53 is - Octave Channel 3 only. SW54 is + Semitone (max 6 semitones) and  SW55 is - Semitone (max 6 semitones).