Convert NRPN to CC

In difference to the CC-to-NRPN example, we want to convert incoming NRPN parameters to common CCs. In order to avoid conflicts, all incoming CC events on Channel #1 will be filtered, only NRPNs will be processed, and once the MSB value has been received, it will be forwarded as 'simple' CC.

Copy the SDCC skeleton into a new directory, open the main.c file and enhance the hooks like described below. Thereafter type "make" in the command shell, and upload the new project.hex file to the core.

/////////////////////////////////////////////////////////////////////////////
//  This function is called by MIOS when a complete MIDI event has been received
/////////////////////////////////////////////////////////////////////////////
void MPROC_NotifyReceivedEvnt(
  unsigned char evnt0, unsigned char evnt1, unsigned char evnt2) __wparam
{
  // static variables don't "forget" their values when the function
  // is called again - we are using them to store the NRPN address/data
  static unsigned char nrpn_msb;
  static unsigned char nrpn_lsb;
  static unsigned char nrpn_value_msb;
  static unsigned char nrpn_value_lsb;

  // check MIDI channel, it should be 0 (-> channel #1)
  if( (evnt0 & 0x0f) == 0 ) {

    switch( evnt0 & 0xf0 ) {
      case 0x80: // Note-Off: 3 bytes
      case 0x90: // Note-On: 3 bytes
      case 0xa0: // Aftertouch: 3 bytes
      case 0xe0: // Pitchbend: 3 bytes
        MIOS_MIDI_TxBufferPut(evnt0);
        MIOS_MIDI_TxBufferPut(evnt1);
        MIOS_MIDI_TxBufferPut(evnt2);
        break;
      case 0xc0: // Program Change: 2 bytes
      case 0xd0: // Poly Aftertouch: 2 bytes
        MIOS_MIDI_TxBufferPut(evnt0);
        MIOS_MIDI_TxBufferPut(evnt1);
        break;

      case 0xb0: // CC: 3 bytes
	// only listen on first MIDI channel
	if( evnt0 == 0xb0 ) {
	  switch( evnt1 ) {
  	    case 0x63: // NRPN MSB
	      nrpn_msb = evnt2; // store it
	      break;
  	    case 0x62: // NRPN LSB
	      nrpn_lsb = evnt2; // store it
	      break;
  	    case 0x26: // NRPN Value LSB
	      nrpn_value_lsb = evnt2; // store it
	      break;
  	    case 0x06: // NRPN Value MSB
	      nrpn_value_msb = evnt2; // store it...

	      // ...and forward CC
	      MIOS_MIDI_TxBufferPut(evnt0);
	      MIOS_MIDI_TxBufferPut(nrpn_lsb); // could also be mapped
	      MIOS_MIDI_TxBufferPut(nrpn_value_msb);
	      break;
  	    default:
	      // all other CCs are ignored
	  }
	} else {
	  // CCs on all other channels are forwarded directly
          MIOS_MIDI_TxBufferPut(evnt0);
          MIOS_MIDI_TxBufferPut(evnt1);
          MIOS_MIDI_TxBufferPut(evnt2);
	}

      default:
        // note: status messages (>= 0xf0) must be handled within MPROC_NotifyReceivedByte)
        break;
     }
  }
}
>

If SysEx or Realtime messages should be forwarded as well, then you need to enhance the MPROC_NotifyReceivedByte() function like shown in this example

A list of available MIOS function can be found here.



Last update: 2018-01-06

Copyright 1998-2018, Thorsten Klose. All rights reserved.