MIDI ACCORDION

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 encoded switches are wired via IN4148 diodes, see schematic circuit diagram. The design transmits MIDI note on/off commands out on channels 1,2,3 notes 48-111,48-59 and 36-47 respectively, shown in table 1. However other tables could be implemented if required.

The accordion sound is produced in a standard General MIDI (GM) map sound module/synthesiser as program change number 22.

• The  MIDI channels 1,2,3 are pre-selected,
• The velocity byte is preset to the half of maximum value.
•  The keyboard encoder is 32-note polyphonic.
• The switches are defined  as in the Key to MIDI Note Number Chart.
• A wiring layout for the circuit is also available.

The Accordion Encoder to MIDI Unit utilizes:

• A Printed Circuit Board (PCB), 
• A pre-programmed 16F877 PIC,
• The on/off switch and associated power-on LED,
• A 9 volt battery connector
• A MIDI 5-pin DIN output socket, see Circuit Diagram
• A screw terminal connector for an external 9-12 volts DC supply
• Three 8-way screw terminal connectors for connecting the external switches, see layout diagram

The Accordion Encoder to MIDI Unit requires:

• a 9v battery or equivalent DC power source
• Required external switches and associated diodes

TOM SCARFF
1 Martello Court
Portmarnock
Dublin
Ireland.

Email: tscarff@eircom.net