MUSIC TECHNOLOGY

 
 

 

 

 

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Circuit Layout

 

 

    

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Circuit Schematic Diagram

  

Switch and Controller MIDI Foot Pedals

This unit converts up to 8 variable potentiometer and  up to 9 switch foot-pedals to an associated MIDI control signal. This unit will work with one, two or up to all 17 inputs, at the same time.

The Switch and Controller MIDI Foot Pedal utilizes:

  • A Printed Circuit Board (PCB), 
  • A pre-programmed 16F877 PIC,
  • 8 inputs for variable potentiometer foot pedals,
  • 9 inputs for switch type foot-pedals,
  • A power-on LED,
  • A 4-way DIP switch which selects the MIDI channel at power-on, see Table 3
  •  a MIDI 5-pin DIN output socket, see Circuit Schematic Diagram
 

The Switch and Controller MIDI Foot Pedal also requires:

 

Operation:

At power-on the DIP switch positions are read and the unit will operate in a MIDI channel as shown in Table 3

 

MIDI Pedal Switch Functions:

Switch Input Selections

MIDI Pedal Functions

1 Sustain
2 Sostenuto
3 Soft Pedal
4 Legato
5 Hold 2
6 Portamento
7 Start
8 Stop
9 Continue

Table 1

 

Sustain Pedal: 

The sustain pedal is also known as the Damper Pedal. When operated it sends out a controller value of CC64. When the pedal is pressed ON the unit outputs a value of 127, when released OFF the unit outputs a value of 0. Tone-generators without the 'half-damper' implemented will interpret a value between 0 and 63 as OFF and a value of 64 to 127 as ON. 

Sostenuto Pedal: 

The sostenuto pedal is a type of selective sustain pedal found on acoustic grand-pianos. Pressing down the pedal, sending controller value CC66 with a value of 127, while holding notes on the keyboard will cause these notes to be sustained after you release them. Any notes played after pressing the pedal will not sustain. When the pedal is released it sends out controller value CC66 with a value of 0.

Soft Pedal:

The soft pedal works in two simultaneous ways. When the pedal is pressed, sending out controller value CC67 with a value of 127, the sound should be slightly softened in terms of volume and there should be a noticeable difference in the tone-colour of the sound. When the pedal is released it sends out controller value CC67 with a value of 0.

Legato Pedal:

When the legato pedal is pressed, sending out controller value CC68 with a value of 127, playing a different note changes the pitch of the current note without re-triggering the attack phase of the envelope of the sound. When the pedal is released it sends out controller value CC68 with a value of 0.

Hold 2 Pedal:

The hold 2 pedal is another type of sustaining pedal used fro sounds with two sustain phases in their envelopes. When the pedal is pressed it sends out controller value CC69 with a value of 127, when the pedal is released it sends out controller value CC69 with a value of 0.

Portamento Pedal :

Portamento or glide is a synthesiser effect. It is mainly used for synthesiser leads and sound effects. The effect is a regular sliding from one note to another, in a similar way to pitch bend, but in this case it is the time taken  rather than the distance that has to be specified.

Portamento uses two separate controllers. Controller CC5 is used to set the portamento Time, how long it takes to change the pitch by a semitone, which has a range of 0-127.  The portamento time value is associated with the variable potentiometer value fed to controller input 8.

When the portamento pedal is pressed it sends out controller value CC65 with a value of 127. When the pedal is released it sends out controller value CC65 with a value of 0.

The portamento effect does not require the playing to be legato, the pitch will always slide from the last note played, however long you pause between the two.

If chords are played with the portamento effect then the sliding becomes haphazard as any note from the first chord could slide to any note of the second.

 

Start Pedal:

When the Start  pedal is operated it sends a MIDI start code when the foot-switch is pressed. This can be used to control the start/stop time of a MIDI hardware/software sequencer, allowing a musician hands free operation.

Stop Pedal:

When the Stop  pedal is operated it sends a MIDI stop code when the foot-switch is pressed.  This can be used to control the start/continue/stop time of a MIDI hardware/software sequencer, allowing a musician hands free operation.

Continue Pedal:

When the Continue  pedal is operated it sends a MIDI continue code when the foot-switch is pressed.  This will continue a MIDI sequence from where it was stopped with the stop pedal. This can be used to control the start/continue/stop time of a MIDI hardware/software sequencer, allowing a musician hands free operation.


 

MIDI Pedal Controller Functions:

Controller Input Selections

MIDI Pedal Functions

1 Volume
2 Modulation
3 Breath Control
4 Pitch
5 Balance
6 Pan
7 Expression
8 Portamento Time

Table 2

 

 

DIP Switch Selections

MIDI Channels
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 3 MIDI Channels