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Wah Switch and Controller MIDI Foot Pedals

 

Wah Switch Controller MIDI/USB Foot Pedal

 

This design is used with a Digidesign Eleven Rack guitar unit to create a midi controller to:

1) Send foot pedal controls between 1-127 on CC# 4 ( FOOT control) to control the wah sweep,
2) Use the pedal's on/off switch for CC# 43 (On = 127 and Off = 0) which will toggle the wah function on/off.

 

This assembled unit converts up to 5 variable potentiometer and  up to 5 switch foot-pedals to an associated MIDI control signal. This unit will work with one, two or up to all 10 inputs, at the same time. This unit can work in standard MIDI mode or via the USB connection. It defaults to standard MIDI Baud rate of 31250. However a  choice is made at power-up via a switch connected to Pin 12 of the Arduino. If the switch/link is open the unit works in standard MIDI Mode and if the switch/link is closed it operates in USB Mode.

 

  

 

 

MIDI&USB WAH Pedals

ITEM#: MIDIUSBWAHPED

PRICE:  €50.00


 

 

 

  

  

  

The Wah Switch and Controller MIDI Foot Pedal utilizes:

  • An assembled Arduino Diecimilia,
  • An assembled  MIDI IN & OUT circuit,
  • 5 inputs for variable potentiometer foot pedals,
  • 5 inputs for switch type foot-pedals,
  • 2 Male Headers x6,
  • 1 Male Header x8,
  • 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 input socket
  •  a MIDI 5-pin DIN output socket, 
  • Switch and potentiometer Circuit Schematic Diagram
  • MIDI IN OUT circuit schematic diagram

 

 

The Wah Switch and Controller MIDI Foot Pedal also requires:

 

  

USB MIDI Setup:

This design  includes a USB chip, it is designed  to program the microcontroller, or provide communication via MIDI/USB.  The MIDI-USB driver information is available.

 

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 by the PWR_SEL jumper. To power the board from the USB connection, place it on the two pins closest to the USB connector, for an external power supply, the two pins closest to the external power jack.

 

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.

 

Note that with the Arduino Duemilanove or Mega the power input selection (USB/EXT.) is automatically selected.

 

Operation:

Note that the unit can be powered via USB or external 9 to 12 Volt DC through the 2.1mm power socket. The power input selection (USB/EXT.) is automatically selected.

 

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

NOTE: Any unused input Analog Pins on the Arduino should be connected to Ground (GND). Otherwise the unit will produce MIDI outputs due to noise pickup on un-connected Analog inputs.

 

Circuit Schematic:

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

A circuit schematic and the wiring diagram of the MIDI IN and OUT circuit shows the Input/Output connections.  There is also a switch and potentiometer Circuit Schematic Diagram. The pin connections on the Arduino are also available.

      

 

 

MIDI Pedal Switch Functions:

Switch Input Selections

MIDI Pedal Functions

1  Sustain
2  Sostenuto
3  Soft Pedal
4  Legato
5  CC#43

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.

    

 


 

MIDI Pedal Controller Functions:

Controller Input Selections

MIDI Pedal Functions

1  Volume (#7)
2  Modulation (#2)
3  Balance (#8)
4  Foot (#4)
5  Pitch

Table 2

   


 

 

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 3 MIDI Channel