How to program MIDI with latest Arduino IDE

Projects Programming
1

I am stuck with my project.
I am using a OnePinCapSense library and I need to put out MIDI notes.
While OnePinCapSense works fine with Arduino 1.8.2 MIDI librarie acts weird.
When I use example given with the MIDI library it compiles OK. When I try to use MIDI.sendNoteOn(42, 127, 1); in my scetch I get the error "MIDI is not declared...."

2

You don't need a MIDI library to send MIDI, just one function is enough:

/* The format of the message to send via serial. Create a new data structure, that can store 3 bytes at once.  This will be easier to send as MIDI. */
typedef struct {
  unsigned int channel : 4;   // second nibble : midi channel (0-15) (channel and status are swapped, because Arduino is Little Endian)
  unsigned int status : 4;    // first  nibble : status message (NOTE_ON, NOTE_OFF or CC (control change) 
  uint8_t data1;              // second byte   : first value (0-127), controller number or note number
  uint8_t data2;              // third  byte   : second value (0-127), controller value or velocity
} 
t_midiMsg;          // We call this structure 't_midiMsg'

void MIDISend(uint8_t status, uint8_t channel, uint8_t data1, uint8_t data2) {
  t_midiMsg msg;
  msg.status = status & 0xF;
  msg.channel = (channel-1) & 0xF; // channels are 0-based
  msg.data1 = data1 & 0x7F;
  msg.data2 = data2 & 0x7F;
  Serial.write((uint8_t *)&msg,3);
}

The MIDI protocol is pretty straightforward, you can find the specs on https://www.midi.org/specifications.

Pieter

P.S. You could also use a shorter function, without a struct, but it's less clear:

void MIDISend(uint8_t status, uint8_t channel, uint8_t data1, uint8_t data2) {
  Serial.write(((status & 0xF) << 4) | ((channel - 1) & 0xF));
  Serial.write(data1 & 0x7F);
  Serial.write(data2 & 0x7F);
}