Push button to MIDI note... note-off being send constantly.

Other Hardware Audio
1

Hi, I've been building a MIDI controller with a Mega 2560. I have all of my analogue controls working nicely but now am having trouble getting my digital push buttons to behave correctly. For some reason it sends repeated note-off messages to ableton constantly until the button is pressed and then stops sending at all until the button is released when it starts sending note-off again. I have tried quite a few ways to stop this happeneing but none have seemed to work.

Here is my code: -

#include <MIDI.h>
#include <midi_Defs.h>
#include <midi_Message.h>
#include <midi_Namespace.h>
#include <midi_Settings.h>
MIDI_CREATE_DEFAULT_INSTANCE();


const int  buttonPin = 3;    // the pin that the pushbutton is attached to

int buttonState = 0;         // current state of the button
int lastButtonState = 0;     // previous state of the button

void setup() {
  // initialize the button pin as an input:
  pinMode(buttonPin, INPUT);
  // begin MIDI communication:
  MIDI.begin(4);
}

void loop() {
  // read the pushbutton input pin:
  buttonState = digitalRead(buttonPin);

// compare the buttonState to its previous state:
  if (buttonState != lastButtonState) {
    if (buttonState == HIGH) {
      MIDI.sendNoteOn(67, 127, 1);
  lastButtonState = buttonState;
  }
      else if (buttonState != lastButtonState) {
        if (buttonState == LOW);
          MIDI.sendNoteOff(67, 0, 1);
  lastButtonState = buttonState;  
  }
  }
}

As you can see I have used if statements to specify when messages should be sent but I'm obviously missing something.

Thanks in advance for any help

2

You have probably got the button wired so that when you push it, it is grounded which means that you should be looking for "buttonState == LOW".
Also, if you aren't using an external pullup resistor, it helps to define the pinMode as INPUT_PULLUP so that the pin isn't floating when it isn't pushed.
If this doesn't fix it, describe exactly how you have wired up the button.

Pete

3

at the moment I have one leg of the button wired to ground and one wired to digital pin 3. That is it.

4

one second... I think what u said about declaring 'PULL-UP' Might have done it... or so it looks like on the onboard LED.

Give me a minute or so to test it in Ableton... I'll let you know how it goes shortly.

5

okay it's almost working. Only now it's sending note.on when i let go and note.off when i press it. So it's inverted. I'm guessing it has something to do with what you said: -

"You have probably got the button wired so that when you push it, it is grounded which means that you should be looking for "buttonState == LOW"."

How can I change this? There is only two pins on the button. I've tried switching them but it has no effect?

Thank A LOT for your help.

6

Okay... I've managed to get it working correctly now. Thanks very much you've been very helpful :slight_smile:

7

You're very welcome :slight_smile: