MIOS C Example

Convert CC#0 to NRPN Cutoff for MC303 and CC#1 to NRPN resonance

We want to create a MIDI converter, which translates the Modwheel Event to a NRPN.

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 { // 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 // check for CC #0 at Channel #1 if ( evnt0 == 0xb0 && evnt1 == 0x00 ) MyFun_Send_MC303_NRPN(evnt0, 0x20, evnt2); // send NRPN LSB = 0x20 (CutOff) else if( evnt0 == 0xb0 && evnt1 == 0x01 ) MyFun_Send_MC303_NRPN(evnt0, 0x20, evnt2); // send NRPN LSB = 0x20 (Resonance) else { // just forward CC without change MIOS_MIDI_TxBufferPut(evnt0); MIOS_MIDI_TxBufferPut(evnt1); MIOS_MIDI_TxBufferPut(evnt2); } default: // note: status messages (>= 0xf0) must be handled within MPROC_NotifyReceivedByte) break; } } }>

As you've propably noticed, the function "MyFun_Send_MC303_NRPN" is called. This function sends a NRPN event, customized for the MC303:

void MyFun_Send_MC303_NRPN( unsigned char evnt0, unsigned char nrpn_lsb, unsigned char value) { MIOS_MIDI_TxBufferPut(evnt0); // send Bn MIOS_MIDI_TxBufferPut(0x63); // Send NRPN MSB 01 (0x63 0x01) MIOS_MIDI_TxBufferPut(0x01); MIOS_MIDI_TxBufferPut(0x62); // Send NRPN LSB (0x62 ) MIOS_MIDI_TxBufferPut(nrpn_lsb); MIOS_MIDI_TxBufferPut(0x06); // send NRPN MSB value (0x06 ) MIOS_MIDI_TxBufferPut(value); }

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