Arduino: Simple MIDI footswitch

I just wanted to share my code for the simple MIDI footswitch I made for live looping. The buttons are all connected like this: http://www.arduino.cc/en/Tutorial/button, and they all send normal midi note on / off commands. The midi out port is connected like this: http://www.roguescience.org/wordpress/building-a-midi-out-controller/part-7-add-a-midi-port/exercise-13/.

You will need the MIDI library and the Bounce library for this code to compile. EDIT: Use the new version of the code and skip the Bounce library.

The footswitch I made has five buttons, but you can easily modify the code for more or fewer buttons. The only things you need to change is the NUMBUTTONS define and the array with midi notes (int note[NUMBUTTONS] = {24,26,28,25,27};). You can also change the midi channel, by changing the MIDICHANNEL define.

Here is the code, short and simple:

/*
    Simple MIDI footswitch 1.0

    by Mikael Norrgard 2012 <http://www.witchmastercreations.com>

    This program is free software: you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
    the Free Software Foundation, either version 3 of the License, or
    (at your option) any later version.

    This program is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    GNU General Public License for more details.

    You should have received a copy of the GNU General Public License
    along with this program.  If not, see <http://www.gnu.org/licenses/>.
*/

#include <Bounce.h>
#include <MIDI.h>

#define BUTTON1 2          // The pin for first button
#define NUMBUTTONS 5       // The number of buttons
#define MIDICHANNEL 11     // The midi channel to use

// For the for-loops
byte i=0;

// Define arrays
Bounce *bouncer;                            // pointer to bouncer objects
byte value[NUMBUTTONS];                     // keeping track of the current pin values
byte previousValue[NUMBUTTONS];             // keeping track of the previous pin values
int note[NUMBUTTONS] = {24,26,28,25,27};    // the array for the midi notes to send, in my case C0, D0, E0, C#0, Eb0

void setup() {

  // Allocate memory for the bouncer objects
  bouncer = (Bounce *) malloc(sizeof(Bounce) * NUMBUTTONS);

  for(i=0;i<NUMBUTTONS;i++)
  {
    // Instantiate five Bounce objects with a 5 millisecond debounce time
    bouncer[i] = Bounce( BUTTON1+i,5 );

    // Initiate the values
    value[i] = LOW;
    previousValue[i] = LOW;

    // Set input pins
    pinMode(BUTTON1+i,INPUT);
  }

  //initialize MIDI
  MIDI.begin(MIDICHANNEL);
}

void loop() {

  // Cycle through all inputs
  for(i=0;i<NUMBUTTONS;i++)
  {
    // Update the bouncer object
    bouncer[i].update();

    // Read the current pin-values
    value[i] = bouncer[i].read();

    // Has the value changed, in other words, has the button been pressed or released?
    if(value[i] != previousValue[i]) {
     // If button has become pressed, send a midi note on message
     if(value[i] == HIGH) {
       MIDI.sendNoteOn(note[i], 127, MIDICHANNEL); // Send note on
     }
     // Otherwise, send a note off message
     else {
       MIDI.sendNoteOff(note[i], 0, MIDICHANNEL); // Send note off
     }
     // Pause for 300ms (this is to further help with button bounces, my buttons are VERY bouncy.
     // This delay does not hurt the function in my case, since the latency for pushing a button is still very short
     delay(300);
     // Set the previous pin state to the current one for next check
     previousValue[i] = value[i];
    }
  }
}

Below is the updated source for 7 buttons (you can easlily modify the code for more buttons). This version does not use the bounce library and uses direct port manipulation for the buttons.

/*
Hiduino ProductID: 0x2050
Hiduino Name: DaemonPedal

Simple MIDI footswitch 2.0

by Mikael Norrgard 2015
http://www.witchmastercreations.com

This program is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.

This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
GNU General Public License for more details.

You should have received a copy of the GNU General Public License
along with this program.  If not, see <http://www.gnu.org/licenses/>.

BUTTON CONNECTIONS
---------------------------
Connect one lead of each button to the input pin and one lead to
ground, simple. This code assume buttons on pins 2-8.
*/

#include <MIDI.h>

#define BUTTON1 2          // The pin for first button
#define NUMBUTTONS 7       // The number of buttons
#define MIDICHANNEL 15     // The midi channel to use
#define LATENCY 50         // The latency
#define DEBOUNCE_TIME 100
#define BUTTON_PRESSED 0

// Define arrays
int  note[NUMBUTTONS]                = {36,37,38,39,40,41,42};// The array for the midi notes to send
byte button_state[NUMBUTTONS]        = {1, 1, 1, 1, 1, 1, 1}; // Values are 0 when buttons are pressed
long button_time_changed[NUMBUTTONS] = {0, 0, 0, 0, 0, 0, 0}; // The time in milliseconds when the button changed status

int i; // For loops
byte iDigitalRead = 0; // Temporary variable for reading buttons
byte iBitValue = 0; // Temporary variable for reading bits from bytes

// Timer
unsigned long currentTime; // the current "time" variable

void setup()
{
  for(int i=BUTTON1;i<BUTTON1+NUMBUTTONS;i++) {
    pinMode(i, INPUT);
    digitalWrite(i, HIGH);
  }

  //initialize MIDI
  MIDI.begin(MIDI_CHANNEL_OMNI); //initialize MIDI at all channels
  MIDI.setThruFilterMode(Full);

  currentTime = millis(); // reset the timer
}

void loop() {

  currentTime = millis(); // get the current "time"

  // Read input midi
  MIDI.read();

  // Check the first 6 buttons
  iDigitalRead = PIND; // Pins 0-7
  for(i=2;i<=7;i++) { // Bits 2-7 are pins 2-7, the button_state array is offset
    iBitValue = bitRead(iDigitalRead, i);
    if(currentTime > (button_time_changed[i-2] + DEBOUNCE_TIME) && iBitValue != button_state[i-2])
    {
      button_state[i-2] = iBitValue;
      button_time_changed[i-2] = currentTime;

      if(iBitValue == BUTTON_PRESSED) { // The button has been pressed
        MIDI.sendNoteOn(note[i-2], 127, MIDICHANNEL); // Send note on
      }
      else {
        MIDI.sendNoteOff(note[i-2], 0, MIDICHANNEL); // Send note off
      }
    }
  }

  // Check the last button
  iDigitalRead = PINB; // Pins 8-13
  for(i=0;i<=0;i++) {// Bit 0 is pin 8
    iBitValue = bitRead(iDigitalRead, i);
    if(currentTime > (button_time_changed[i+6] + DEBOUNCE_TIME) && iBitValue != button_state[i+6])
    {
      button_state[i+6] = iBitValue;
      button_time_changed[i+6] = currentTime;

      if(iBitValue == BUTTON_PRESSED) { // The button has been pressed
        MIDI.sendNoteOn(note[i+6], 127, MIDICHANNEL); // Send note on
      }
      else {
        MIDI.sendNoteOff(note[i+6], 0, MIDICHANNEL); // Send note off
      }
    }
  }
}

Photo from the bottom of the pedal with the bottom cover removed: