MIDI Concertina The MIDI Concertina encoder is capable of encoding the required 48 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, see switches circuit diagram. The design is based on a two sided diatonic keyboard with 24+24 keys for the Left hand and for the Right hand. This design is for an English Concertina  but other keys could be encoded if required.        MIDI CONCERTINA ITEM#: MIDICONCERTINA PRICE:  €35.00       The Concertina Encoder to MIDI Unit utilizes: The MIDI channel is set to channel 1 for left and right hand 24 + 24 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 Concertina Encoder to MIDI Unit requires:   A 9v battery or equivalent DC power source, Required 48 external switches and associated diodes,

Circuit Schematic:

A circuit schematic of the Miduino Concertina shows the switch connections. Note that for this project the 4-way DIL switch is not required. 

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 Concertina Wiring:

The switches are organized in a 8 x 6 matrix (48 switches) arrangement. The switch keys are wired as shown in the  Wiring diagram.

So, for example, terminal connected to D10  is wired to one side of the 8 key switches SW 0 to SW7 and the wire can be looped from one key switch to the next. Also the other sides of these switches/diodes are connected down to Miduino contacts D2 to D9.

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 7 other diodes. For example Anode (A) of diode DO is looped to D8 then to D16 then to D24 etc. down to D47 and finally to digital terminal D2 on the Miduino.

The rest of the wiring is done in a similar manner.