Midi controler with mega 2560 and encoders

Using Arduino Project Guidance
1

Good morning,

I would like to make a midi controller composed of 25 encoders and 8 push buttons (on/off),
only midi out because I don't need feedback.

I have an old arduino mega 2560 r2 card for this.

I did the test with arduino IDE, example/04.communication/Midi and it works well with the female din socket (midi), so I think I don't need any more libraries?

I've been searching the internet for a long time for an example that would help me, but I can't find it.

I specify that I am a beginner

Does anyone have an idea?

ps: sorry for my english, it's with google translate...

2

If you need just the encoders and a couple of push buttons, you might get away with just polling them for changes. If there's much other stuff going on in your code, you'll have to resort to interrupts, which is much more tricky.

These examples could prove helpful:

If you want to go the interrupt route, see:

3

Thank you for your reply PeterP.

This is all very complicated for me.

Everyone here seems to say that it's easier for the midi language to work with:
Arduino Due, Arduino Leonardo, Arduino Micro, Arduino Nano 33 IOT, Arduino Zero, Arduino MKR Zero, Arduino MKR1000 ...or a teensy

I looked at these boards and arduino due to 54 Digital I/O Pins so would be fine for my project.
is it better for me to buy this?

4

If you need MIDI over USB, then you'll indeed want a different board. If you just want to send MIDI over DIN, you only need a UART, and the Mega will get the job done (at least the MIDI side of it, not sure about the encoders).

At two pins per encoder, plus 8 for the switches, 54 pins would not suffice.

I'm not a fan of the Due, the standard library is broken, and the toolchain hasn't been updated for years (they still use GCC 4.8, while GCC 13.0 is expected to come out in the coming weeks).

I'd probably recommend a Teensy, but even the Teensy 4.1 might not have enough pins (55, but only 42 are breadboard-accessible).

So I guess you'll need some kind of IO expander, unfortunately complicating the project even further.
For example, the MCP23017 supports up to 8 encoders, and is supported by the Control Surface library, but I've never really tried using multiple of them in a single build.

5

Thanks for your help Peter,

So maybe I'll revise my project:
With 17 encoder and 10 buttons.

In this case the teensy 4.1 will do the trick.

Because I want to make a controller for an audio channel strip plugin with an equalizer part and a compressor part.
I will do the compressor later :slight_smile:

It is important to use encoders to be able to directly access the value displayed on the plugin.

by the way, what kind of encoder should you buy? so I order everything at the same time.
and for the buttons, I need switches (spst) or inverters (spdt)?

6

Good morning,

I found this code from "Notes and volts" which works fine on my mega board.

I therefore think to stay with the mega card and a midi din socket.

I would just like to add to this code instructions for very simple encoders (without buttons).

I remind you that I don't use midi in, I don't need information that comes back to the card.
Thank you for your return.

#include <MIDI.h>
#include "Controller.h"

/*************************************************************
  MIDI CONTROLLER

  by Notes and Volts
  www.notesandvolts.com

  Version 1.2 **Arduino UNO ONLY!**
 *************************************************************/

MIDI_CREATE_DEFAULT_INSTANCE();

//************************************************************
//***SET THE NUMBER OF CONTROLS USED**************************
//************************************************************
//---How many buttons are connected directly to pins?---------
byte NUMBER_BUTTONS = 0;
//---How many potentiometers are connected directly to pins?--
byte NUMBER_POTS = 1;
//---How many buttons are connected to a multiplexer?---------
byte NUMBER_MUX_BUTTONS = 0;
//---How many potentiometers are connected to a multiplexer?--
byte NUMBER_MUX_POTS = 0;
//************************************************************

//***ANY MULTIPLEXERS? (74HC4067)************************************
//MUX address pins must be connected to Arduino UNO pins 2,3,4,5
//A0 = PIN2, A1 = PIN3, A2 = PIN4, A3 = PIN5
//*******************************************************************
//Mux NAME (OUTPUT PIN, , How Many Mux Pins?(8 or 16) , Is It Analog?);


//Mux M1(10, 16, false); //Digital multiplexer on Arduino pin 10
//Mux M2(A5, 8, true); //Analog multiplexer on Arduino analog pin A0
//*******************************************************************


//***DEFINE DIRECTLY CONNECTED POTENTIOMETERS************************
//Pot (Pin Number, Command, CC Control, Channel Number)
//**Command parameter is for future use**

Pot PO1(A0, 0, 1, 1);
//Pot PO2(A1, 0, 10, 1);
//Pot PO3(A2, 0, 22, 1);
//Pot PO4(A3, 0, 118, 1);
//Pot PO5(A4, 0, 30, 1);
//Pot PO6(A5, 0, 31, 1);
//*******************************************************************
//Add pots used to array below like this->  Pot *POTS[] {&PO1, &PO2, &PO3, &PO4, &PO5, &PO6};
Pot *POTS[] {&PO1};
//*******************************************************************


//***DEFINE DIRECTLY CONNECTED BUTTONS*******************************
//Button (Pin Number, Command, Note Number, Channel, Debounce Time)
//** Command parameter 0=NOTE  1=CC  2=Toggle CC **

//Button BU1(2, 0, 60, 1, 5 );
//Button BU2(3, 0, 61, 1, 5 );
//Button BU3(4, 0, 62, 1, 5 );
//Button BU4(5, 0, 63, 1, 5 );
//Button BU5(6, 0, 64, 1, 5 );
//Button BU6(7, 0, 65, 1, 5 );
//Button BU7(8, 1, 64, 1, 5 );
//Button BU8(9, 2, 64, 1, 5 );
//*******************************************************************
//Add buttons used to array below like this->  Button *BUTTONS[] {&BU1, &BU2, &BU3, &BU4, &BU5, &BU6, &BU7, &BU8};
Button *BUTTONS[] {};
//*******************************************************************


//***DEFINE BUTTONS CONNECTED TO MULTIPLEXER*************************
//Button::Button(Mux mux, byte muxpin, byte command, byte value, byte channel, byte debounce)
//** Command parameter 0=NOTE  1=CC  2=Toggle CC **

//Button MBU1(M1, 0, 0, 70, 1, 5);
//Button MBU2(M1, 1, 1, 71, 1, 5);
//Button MBU3(M1, 2, 2, 72, 1, 5);
//Button MBU4(M1, 3, 0, 73, 1, 5);
//Button MBU5(M1, 4, 0, 74, 1, 5);
//Button MBU6(M1, 5, 0, 75, 1, 5);
//Button MBU7(M1, 6, 0, 76, 1, 5);
//Button MBU8(M1, 7, 0, 77, 1, 5);
//Button MBU9(M1, 8, 0, 78, 1, 5);
//Button MBU10(M1, 9, 0, 79, 1, 5);
//Button MBU11(M1, 10, 0, 80, 1, 5);
//Button MBU12(M1, 11, 0, 81, 1, 5);
//Button MBU13(M1, 12, 0, 82, 1, 5);
//Button MBU14(M1, 13, 0, 83, 1, 5);
//Button MBU15(M1, 14, 0, 84, 1, 5);
//Button MBU16(M1, 15, 0, 85, 1, 5);
//*******************************************************************
////Add multiplexed buttons used to array below like this->  Button *MUXBUTTONS[] {&MBU1, &MBU2, &MBU3, &MBU4, &MBU5, &MBU6.....};
Button *MUXBUTTONS[] {};

//*******************************************************************


//***DEFINE POTENTIOMETERS CONNECTED TO MULTIPLEXER*******************
//Pot::Pot(Mux mux, byte muxpin, byte command, byte control, byte channel)
//**Command parameter is for future use**

//Pot MPO1(M2, 0, 0, 1, 1);
//Pot MPO2(M2, 1, 0, 7, 1);
//Pot MPO3(M2, 2, 0, 50, 1);
//Pot MPO4(M2, 3, 0, 55, 2);
//Pot MPO5(M2, 4, 0, 50, 1);
//Pot MPO6(M2, 5, 0, 55, 2);
//Pot MPO7(M2, 6, 0, 50, 1);
//Pot MPO8(M2, 7, 0, 55, 2);
//Pot MPO9(M2, 8, 0, 50, 1);
//Pot MPO10(M2, 9, 0, 55, 2);
//Pot MPO11(M2, 10, 0, 50, 1);
//Pot MPO12(M2, 11, 0, 55, 2);
//Pot MPO13(M2, 12, 0, 50, 1);
//Pot MPO14(M2, 13, 0, 55, 2);
//Pot MPO15(M2, 14, 0, 50, 1);
//Pot MPO16(M2, 15, 0, 55, 2);
//*******************************************************************
//Add multiplexed pots used to array below like this->  Pot *MUXPOTS[] {&MPO1, &MPO2, &MPO3, &MPO4, &MPO5, &MPO6.....};
Pot *MUXPOTS[] {};
//*******************************************************************


void setup() {
  MIDI.begin(MIDI_CHANNEL_OFF);
}

void loop() {
  if (NUMBER_BUTTONS != 0) updateButtons();
  if (NUMBER_POTS != 0) updatePots();
  if (NUMBER_MUX_BUTTONS != 0) updateMuxButtons();
  if (NUMBER_MUX_POTS != 0) updateMuxPots();
}


//*****************************************************************
void updateButtons() {

  // Cycle through Button array
  for (int i = 0; i < NUMBER_BUTTONS; i = i + 1) {
    byte message = BUTTONS[i]->getValue();

    //  Button is pressed
    if (message == 0) {
      switch (BUTTONS[i]->Bcommand) {
        case 0: //Note
          MIDI.sendNoteOn(BUTTONS[i]->Bvalue, 127, BUTTONS[i]->Bchannel);
          break;
        case 1: //CC
          MIDI.sendControlChange(BUTTONS[i]->Bvalue, 127, BUTTONS[i]->Bchannel);
          break;
        case 2: //Toggle
          if (BUTTONS[i]->Btoggle == 0) {
            MIDI.sendControlChange(BUTTONS[i]->Bvalue, 127, BUTTONS[i]->Bchannel);
            BUTTONS[i]->Btoggle = 1;
          }
          else if (BUTTONS[i]->Btoggle == 1) {
            MIDI.sendControlChange(BUTTONS[i]->Bvalue, 0, BUTTONS[i]->Bchannel);
            BUTTONS[i]->Btoggle = 0;
          }
          break;
      }
    }

    //  Button is not pressed
    if (message == 1) {
      switch (BUTTONS[i]->Bcommand) {
        case 0:
          MIDI.sendNoteOff(BUTTONS[i]->Bvalue, 0, BUTTONS[i]->Bchannel);
          break;
        case 1:
          MIDI.sendControlChange(BUTTONS[i]->Bvalue, 0, BUTTONS[i]->Bchannel);
          break;
      }
    }
  }
}
//*******************************************************************
void updateMuxButtons() {

  // Cycle through Mux Button array
  for (int i = 0; i < NUMBER_MUX_BUTTONS; i = i + 1) {

    MUXBUTTONS[i]->muxUpdate();
    byte message = MUXBUTTONS[i]->getValue();

    //  Button is pressed
    if (message == 0) {
      switch (MUXBUTTONS[i]->Bcommand) {
        case 0: //Note
          MIDI.sendNoteOn(MUXBUTTONS[i]->Bvalue, 127, MUXBUTTONS[i]->Bchannel);
          break;
        case 1: //CC
          MIDI.sendControlChange(MUXBUTTONS[i]->Bvalue, 127, MUXBUTTONS[i]->Bchannel);
          break;
        case 2: //Toggle
          if (MUXBUTTONS[i]->Btoggle == 0) {
            MIDI.sendControlChange(MUXBUTTONS[i]->Bvalue, 127, MUXBUTTONS[i]->Bchannel);
            MUXBUTTONS[i]->Btoggle = 1;
          }
          else if (MUXBUTTONS[i]->Btoggle == 1) {
            MIDI.sendControlChange(MUXBUTTONS[i]->Bvalue, 0, MUXBUTTONS[i]->Bchannel);
            MUXBUTTONS[i]->Btoggle = 0;
          }
          break;
      }
    }
    //  Button is not pressed
    if (message == 1) {
      switch (MUXBUTTONS[i]->Bcommand) {
        case 0:
          MIDI.sendNoteOff(MUXBUTTONS[i]->Bvalue, 0, MUXBUTTONS[i]->Bchannel);
          break;
        case 1:
          MIDI.sendControlChange(MUXBUTTONS[i]->Bvalue, 0, MUXBUTTONS[i]->Bchannel);
          break;
      }
    }
  }
}
//***********************************************************************
void updatePots() {
  for (int i = 0; i < NUMBER_POTS; i = i + 1) {
    byte potmessage = POTS[i]->getValue();
    if (potmessage != 255) MIDI.sendControlChange(POTS[i]->Pcontrol, potmessage, POTS[i]->Pchannel);
  }
}
//***********************************************************************
void updateMuxPots() {
  for (int i = 0; i < NUMBER_MUX_POTS; i = i + 1) {
    MUXPOTS[i]->muxUpdate();
    byte potmessage = MUXPOTS[i]->getValue();
    if (potmessage != 255) MIDI.sendControlChange(MUXPOTS[i]->Pcontrol, potmessage, MUXPOTS[i]->Pchannel);
  }
}
7

Why add it to that code?

If you want instructions for simple encoders that send MIDI, see the example I linked to earlier: Control Surface: RotaryEncoder.ino

To use a DIN socket, use the HardwareSerialMIDI_Interface.

#include <Control_Surface.h>

HardwareSerialMIDI_Interface midi {Serial};

CCRotaryEncoder enc {
  {2, 3},       // pins
  MCU::V_POT_1, // MIDI address (CC number + optional channel)
  1,            // optional multiplier if the control isn't fast enough
};

void setup() { Control_Surface.begin(); }
void loop() { Control_Surface.loop(); }
8

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