works: MIDI-IN: code + schematics

When I plugged in the midi interface that I bought it was already dysfunctional. I would play a note on the keyboard, and the computer would play a note only after I released a key. When I checked the midi commends that were being received by the purchased interface, it was giving a note off command when I pressed a key. I was never able to fix that. Well it doesn't seem like there is anything to try other then play with the baud rate. But thank you very much for all of you help. I appreciate it.

I think you should look at the settings of your keyboard instead of the interface. The keyboard sends commands, the interface is just a translator, not an interpreter.

So I got this working and now modified the code to play a sound of the arduino, but I only get a quick beep and that's it.

If I hold a key down on my controller I don't get a continuos sound. I've simply changed the code to have a playsound routine that is played when a 'note on' command arrives. I assume midi doesn't keep sending a 'note on' command so it only makes it though that part of the if statement once, no matter how long I hold down the key.

I've tried a while loop with a statement to keep playing unless a 'note off' (128) is received with a serial.read inside the loop but then it never kick out off it

Suggestions? or am I missing something stupid because it was late at night?

SUYC !

(=show us your code)

This is what I have right now, I know it's ridiculously simple, just trying to get out a square wave.

It's hacked out of some other code I have.

With this code it'll sound one note and then just stick on it

//variables setup

byte incomingByte;
byte note;
byte velocity;


int statusLed = 13;   // select the pin for the LED

int action=2; //0 =note off ; 1=note on ; 2= nada


//setup: declaring iputs and outputs and begin serial
void setup() {
  pinMode(statusLed,OUTPUT);   // declare the LED's pin as output


  //start serial with midi baudrate 31250 or 38400 for debugging
  Serial.begin(31250);        
  digitalWrite(statusLed,HIGH);  
}

//loop: wait for serial data, and interpret the message
void loop () {
  if (Serial.available() > 0) {
    // read the incoming byte:
    incomingByte = Serial.read();

    // wait for as status-byte, channel 1, note on or off
    if (incomingByte== 144){ // note on message starting starting
      action=1;
    }
    else if (incomingByte== 128){ // note off message starting
      action=0;
    }
   
    else if ( (action==0)&&(note==0) ){ // if we received a "note off", we wait for which note (databyte)
      note=incomingByte;

      note=0;
      velocity=0;
      action=2;
    }
    else if ( (action==1)&&(note==0) ){ // if we received a "note on", we wait for the note (databyte)
      note=incomingByte;

    }
    else if ( (action==1)&&(note!=0) ){ // ...and then the velocity
      velocity=incomingByte;
      while (incomingByte!=128)
      {
        freqout(note);
        incomingByte = Serial.read();

      }
      note=0;
      //velocity=0;
      action=0;
    }
    else{
      //nada
    }
  }
}


void freqout(int freq)
{
  int hperiod;
  hperiod = (500000 / freq);
  analogWrite(12, (255));
  delayMicroseconds(hperiod);
  digitalWrite(12,LOW);
  delayMicroseconds(hperiod - 1);

}

Hi,

else if ( (action==0)&&(note==0) ){ // if we received a "note off", we wait for which note (databyte)
      note=incomingByte;

Here, you do not read the new incoming byte, you have to put
incomingByte = Serial.read();
somewhere again to have to new incoming byte in incomingByte. Do you get it ?
Idem for the velocity.

I think you should rater have a

status = Serial.read();
command = Serial.read();
value = Serial.read();

after the Serial.available(), it would be clearer :wink:

Tell me if I'm not clear enough!

I think I understand. separating each byte into a different variable? Does MIDI commands always come in 3 byte chunks? That would make it easer to break up the commands then having to use the if statement.

Yes, most MIDI commands are in 3 bytes.
To be sure, just in case, read the status byte to know if it is in 3 bytes by type.
I suggest you to look here to better understand how all the protocol works and the possibilities: http://www.blitter.com/~russtopia/MIDI/~jglatt/tech/midispec.htm :wink:

I can get it to play a note, but I can't get it to hold a note when I hold a key down. I only get a quick note when I first press and then again when I release the key.

Well I got it to work using this code.

byte incomingByte;
byte note;
byte velocity;
byte check;
int statusLed = 13;   


void setup() 
{
  //start serial with midi baudrate 31250 or 38400 for debugging
  Serial.begin(31250);
  digitalWrite(statusLed, HIGH);
}


void loop () 
{

  if (Serial.available() > 0) 
  {
    incomingByte = Serial.read();
    delayMicroseconds(400);

    if (incomingByte== 144)
    {
      note = Serial.read();
      delayMicroseconds(400);
      velocity = Serial.read();

      while (check!= 128 )
      {
        check = Serial.read();
        freqout(note);
      }
    }
    check=0;
  }
}


void freqout(int freq)
{
  int hperiod;

  hperiod = (500000 / (freq*2));
  analogWrite(12, 255);
  delayMicroseconds(hperiod);
  digitalWrite(12, LOW);
  delayMicroseconds(hperiod-1);
}

But it only works if I send midi from live on my computer. If i try to use my keyboard controller it will triger a note and the just hold it on forever shrug

Also I had to use the micro second delays to read the serial info, but now if I have 2 note trigger right next to the other it will miss the second one, I assume due to the delay.

If you have and LCD, this could be a way to know what's exactly happening. Some keyboard are strange sometimes.
But note that often keyboards send a note on with velocity instead on note off.

Yeah that's what I'm thinking is going on. I wish I could get rid of those delays but when I do it quits working.

Yes, it should be possible, I didn't use some in my controller.

I just can't get it to work without the delays, is it just blowing by the data in the serial stream with no delays?

I rigged up a LCD and when there is no delays both the note and velocity are read as 255 all the time, no idea!

You perhaps modified it now, but that is a bit strange...

      while (check!= 128 )
      {
        check = Serial.read();
        freqout(note);
      }
    }

Hey guys,

I've managed to get a small instrument working using this code, but I've also encountered the same problem as Captain Credible (reply #41 on page 3), in that through some MIDI interfaces I can't play more than one note.

If I connect the instrument directly to my MIDI keyboard, I can play polyphonically, but if I play through my keyboard into MIDI-OX and out through a separate MIDI interface (a MOTU MIDI Express XT) I can only play monophonically.

Does anyone have an idea as to why this might be happening?

At first I thought it was because of the note-off differences, between actually specifying a note-off message (128) and a note-on with velocity = 0, but as far as I can tell they both do the note-on, vel=0 thing.

I've been racking my brain all day over this, but I'm truly stumped. Any help would be very gratefully received.

MIDI portion of code below:

  if (Serial.available() > 0) {
    blink();
    incomingByte = Serial.read();
    if (incomingByte == 144) {
      action = 1;
    }else if (incomingByte == 128) {
      action = 0;
    }else if ((action == 0) && (note == 0)) {
      note = incomingByte;
      playNote(note, 0);
      note = 0;
      velocity = 0;
      action = 2;
    }else if ((action == 1) && (note == 0)) {
      note = incomingByte;
    }else if ((action == 1) && (note != 0)) {
      velocity = incomingByte;
      playNote(note, velocity);
      note = 0;
      velocity = 0;
      action = 0;
    }else{
    }
  }

Hi All.
I am new to the arduino, but i am fairly handy with electronics. i built my setup according to the schematic, except with a 4 channel opto from sparkfun which i had lying around. I connected everything to the correct corresponding pins, and now all that happens when everything is connected is a stream of serial gibberish that doesnt change when i do something on the piano. Any ideas?

Thank you!

Hi everyone,
Ive been trying to get this to work for a while,but no luck. It seems that the arduino is not recieving any data through RX. Like others, many posts back, I get a LED to flicker when connected to +5v and pin 5 of the optoisolator( when the RX is not connected). I measure about 5.2 v on the pin and a 10th of a volt difference corresponding to keystrokes.
I get nothing coming in on the serial monitor and even the simplest, one led sketches dont work. I am using a microkorg but have also tried a sci prohet 600. I tried changing the baud. I checked for loose connections, cold soldered joint, and my diecimila is fine other wise.
Any suggestions? It seems a few others had this problem but there were no real solutions posted. Id really appreciate any help. Thanks

ok, I got it to work briefly but then I unhooked the RX input and when i put it back it no longer works. I used this:

//variables setup
byte incomingByte;

int statusLed = 13;   // select the pin for the LED


//setup: declaring iputs and outputs and begin serial
void setup() {
  pinMode(statusLed,OUTPUT);   // declare the LED's pin as output
  Serial.begin(31250);        //start serial with midi baudrate 31250 or 38400 for debugging
  digitalWrite(statusLed,LOW);
}


void loop () {
 if (Serial.available() > 0) {

    incomingByte = Serial.read();
    // wait for as status-byte, channel 1, note on or off
    if (incomingByte==144){ // 144 is note on ch1
      digitalWrite(statusLed, HIGH);
      delay(20);
      digitalWrite(statusLed, LOW);
      delay(1);
    }

 }
}

This is how I got it to work ... uploaded this sketch (for like the 20th time) and it didnt work...no surprise.
then I took the lead from pin 5 of the opto and directly touch pin 2 on the atmega( the rx pin) then I stuck a 1k resistor between therx and tx sockets, removed it and then put the lead from pin 5 of the opto back into the rx socket. Ta-DA that did it ...worked fine! However... After I removed the input lead and put it back it stoped working and now nothing. I checked continuity.... I think everything is good. I get a strong beep when the probes are directly on the opto's output and the atmega RX pin 2. I am pretty sure the hardware is ok. I think somehow my arduino doesnt want to read incoming data, though it loads sketches fine.

Ok, I got it to work, but not with a 4n28. I tried 10 of them, with every resistor combo imaginable. I could get a led flicker (between +5v and pin 5,with the rx disconnected ), but it did nothing for the arduino. Nothing was being read. Finally i tried another opto, a cny 17-4. It has a similar pinout as the 4n28 and I substituted the 100k for a 220k and the 3.3k for 2.2k. works perfectly(for me).

It seems that there were/are a few others who had trouble with this circuit and the arduino seemingly not being able to read any data.
Perhaps for some, there is a problem with using the 4n28. i dont know what, though. It makes no sense to me. A circuit this simple and that has been repeatedly verified by so many, shouldnt be this contrary.

Anyone have any ideas?