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Topic: MIDI out messages doesn't work with external power supply  (Read 240 times) previous topic - next topic

galshten

Hi
Trying to build an Arduino MIDI controller that only sends data, I use the attached test code which suppose to send a NoteOn and then NoteOff MIDI massage repeatably via Tx pin.
It works just fine when the Arduino is connected to the computer through the USB port, but when I try to use a power supply of 12V, 1.5A everything on the board looks fine, but MIDI massages being sent continuously and contains random staff.
I use MIDI OX to read the MIDI that comes from the Arduino so I can see what I got according to what I expect.

Attached is a photo of what I get in MIDI-OX when the Arduino is powered with external supply.

Thanks a lot


the test code:
Code: [Select]
#include <MIDI.h>

#define LED 13

MIDI_CREATE_DEFAULT_INSTANCE();

void setup()
{
  pinMode(LED, OUTPUT);
  MIDI.begin(MIDI_CHANNEL_OFF);
}

void loop()
{
  digitalWrite(LED, HIGH);
  MIDI.sendNoteOn(60, 127, 1);
  delay(1000);        
  MIDI.sendNoteOff(60, 0, 1);
  digitalWrite(LED, LOW);
  delay(1000);
}


Grumpy_Mike

How is it wired up?
This sort of problem normally happens because the ground is not connected.
What sort of Arduino do you have?
How are you connecting it to your midi device?

galshten

Im using  Arduino Uno


Its a little bit hard to understand from the pics, but the wiring is:
External supply to the Arduino built in jack, and then the exact same wiring as here:
https://www.arduino.cc/en/Tutorial/Midi

then I use this cheap MIDI to USB cable you can see in the close up picture. I just opened the case for some modification. and in the close up picture the black wire is MIDI V+ and the red wire is the MIDI tx.


I tried to ground the rx pin of the Arduino without success

Thanks

Grumpy_Mike

I am a bit puzzled by those photos. It seems you have connected the MIDI out from the USB lead to a MIDI out interface on the Arduino.

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