MIOS C Example

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: 2024-05-08