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/*
* midi.c
*
* Created: 12.06.2017 20:43:47
* Author: Jonas
*/
#include "midi.h"
static const uint16_t midi_code_frequency_table[] = {8,9,9,10,10,11,12,12,13,14,15,15,16,17,18,19,21,22,23,25,26,28,29,31,33,35,37,39,41,44,46,49,52,55,58,62,65,69,73,78,82,87,93,98,104,110,117,123,131,139,147,156,165,175,185,196,208,220,233,247,262,277,294,311,330,349,370,392,415,440,466,494,523,554,587,622,659,698,740,784,831,880,932,988,1047,1109,1175,1245,1319,1397,1480,1568,1661,1760,1865,1976,2093,2217,2349,2489,2637,2794,2960,3136,3322,3520,3729,3951,4186,4435,4699,4978,5274,5588,5920,6272};
static uint8_t midi_recv_ptr = 0;
ISR(USART_RXC_vect)
{
midi_recv_buffer[midi_recv_ptr] = UDR;
midi_recv_ptr++;
}
void midi_setup()
{
midi_active_channels = 0x00;
DDRA = 0xff;
PORTA = 0xff;
//UART init
unsigned int ubrr = (F_CPU / (16 * _MIDI_LINK_SPEED)) - 1;
UBRRH = (unsigned char) (ubrr>>8) & 0xff;
UBRRL = (unsigned char) ubrr & 0xff;
UCSRB = (1<<RXEN) | (1<<TXEN) | (1<<RXCIE); //Enable Tx, Rx and Rx Interrupt
UCSRC = (1<<URSEL) | (1<<USBS) | (3<<UCSZ0);
}
void midi_process()
{
if(!midi_recv_avail())
return;
char data[3] = {0x00, 0x00, 0x00};
char command, /*channel,*/ note, velocity;
data[0] = midi_get_recv_buf();
data[1] = midi_get_recv_buf();
data[2] = midi_get_recv_buf();
/*channel = data[0] & 0x0f; //Mask out last 4 bits*/
command = (data[0] >> 4) & 0x0f; // Shift command into first 4 bits;
note = data[1];
velocity = data[2];
midi_command(command, note, velocity);
}
void midi_command(char _cmd, char _note, char _vel)
{
switch(_cmd)
{
case 0x08: //Note off
PORTA = 1;
midi_update_note(_note, 0);
break;
case 0x09: //Note on
PORTA = 2;
midi_update_note(_note, 1);
break;
/*
case 0x0A:break; //Note Fade Out
case 0x0B:break; //Control Change
case 0x0C:break; //Channel Fade Out
case 0x0E:break; //Note Pitch change
*/
default:break;
}
}
uint8_t midi_recv_avail()
{
return midi_recv_ptr;
}
char midi_get_recv_buf()
{
if(midi_recv_ptr > 0)
midi_recv_ptr--;
else
return 0x00;
return midi_recv_buffer[midi_recv_ptr];
}
void midi_update_note(uint16_t _note, uint8_t _status)
{
if(_status) //Note on
{
int i;
for(i = 0; i < 8; i++) //search for first free channel
if(!(midi_active_channels & (1<<i)))
break;
midi_current_notes[i] = _note; //write current note to channel
midi_active_channels |= (1<<i); //set channel active
floppy_set_frequency(i, floppy_calc_freq(midi_code_frequency_table[_note]) ); //play note
}
else //Note off
{
int i;
for(i = 0; i < 8; i++) //search for active channel playing _note
{
if(midi_current_notes[i] == _note)
{
floppy_set_frequency(i, 0); //mute
midi_current_notes[i] = 0xff; //unset current, 0xff is outside MIDI standards
midi_active_channels &= ~(1<<i); //unset channel active
break;
}
}
}
}
void midi_uart_out(unsigned char _c)
{
/* Wait for empty transmit buffer */
while ( !( UCSRA & (1<<UDRE)) )
;
/* Put data into buffer, sends the data */
UDR = _c;
}
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