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MIDI Ribbon/Softpot Controller

 

MIDI Ribbon Controller

This is a simple MIDI project, utilizing the Arduino design, to  output  MIDI Note ON/OFF and Pitch Bend control signals when a ribbon/softpot variable potentiometer is adjusted. When the ribbon/softpot is pressed a MIDI Note On message is transmitted. While it is still pressed a MIDI Pitch Bend message is sent if the finger is moved. When the finger is removed the MIDI Note Off message is transmitted.

  

 

 

 

*Click to Enlarge*

 

 

MIDI Ribbon Controller

ITEM#: MIDIRIBCON

PRICE:  €50.00


 

 

The MIDI Ribbon Controller unit utilizes:

  • An assembled, built and tested Arduino board including a suitable pre-programmed microcontroller,
  • A 2.1mm power socket, and associated LED, 
  • A MIDI detection LED,
  • A 4-way DIP switch, which selects the MIDI channel at power-on, shown in table 1
  • A 150mm wired MIDI 5-pin DIN input socket,
  • A 150mm wired MIDI 5-pin DIN output socket, 
  •  0.1" pin-terminal inputs/outputs,
  • The circuit schematic is available,
  • MIDI available/transmit LED

 

 

The MIDI Ribbon Controller also requires:

  • A 9v battery or equivalent DC power source
  • A 100k ohm 0.25W resistor
  • A ribbon/softpot linear potentiometer (Sparkfun Electronics)

 

Operation:

A MIDI Ribbon control signal is transmitted when a softpot variable potentiometer is adjusted. The ribbon/softpot controller is available from Sparkfun Electronics in different sizes.

 

 

The MIDI command is channel (1-16) dependent. The MIDI channel, that the volume controller affects, is set by the 4-way DIP switch selection, shown in Table 1 below.

 

Design Requirements:

The design is a compromise of the number of individual notes that a finger can play separately on any given ribbon controller length. It is similar to a violin. Except a violin has continuous pitch changes along its length. Whereas the ribbon has specific MIDI Note On positions and THEN variable Pitch Bend.

If you consider the width of a finger is 1/2" to 3/4" then the controller length can be divided by these values to determine the maximum range of notes. The ribbon/softpot controller is available in different lengths.

For a 18 inch (500 mm) long ribbon controller with 3/4" finger, number of notes would be 24
For a 300mm -11.81 " long ribbon controller with 3/4" finger, number of notes would be approx. 16
For a 200mm -7.84 " long ribbon controller with 3/4" finger, number of notes would be approx. 10

For a 18 inch (500 mm) long ribbon controller with 1/2" finger, number of notes would be 36
For a 300mm -11.81 " long ribbon controller with 1/2" finger, number of notes would be approx. 24
For a 200mm -7.84 " long ribbon controller with 1/2"finger, number of notes would be approx. 16

So there is some compromise in choosing the design parameters. Perhaps if used by adults or children. However if you choose one of the above, number of notes choices, it can be pre-programmed into the design. 

 

 

MIDI IN/OUT Wiring:

 

 MIDI_IN_OUT_CONNECTIONS.JPG (212235 bytes)

     *Click to Enlarge*

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

 

 

  

 

  

Power Supply:

The  Arduino/Freeduino etc. Diecimila can be powered via the USB connection or with an external power supply. The power source is selected automatically.

 

External (non-USB) power can come either from an AC-to-DC adapter (wall-wart) or battery. The adapter can be connected by plugging a 2.1mm center-positive plug into the board's power jack. Leads from a battery can be inserted in the Gnd and Vin pin headers of the POWER connector. A low dropout regulator provides improved energy efficiency.

 

The board can operate on an external supply of 7 to 20 volts. If supplied with less than 7V, however, the 5V pin may supply less than five volts and the board may be unstable. If using more than 12V, the voltage regulator may overheat and damage the board. The recommended range is 7 to 12 volts.

 

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DIP Switch Selections

MIDI 

Channel

4 3 2 1
on on on on 1
on on on off 2
on  on  off on 3
on on off off 4
on off on on 5
on off on off 6
on off off on 7
on off off off 8
off on on on 9
off on on off 10
off on  off on 11
off on off off 12
off off on on 13
off off on off 14
off off off on 15
off off off off 16

Table 1 MIDI Channel