Synth Nedir?
Synthesizer farklı türde bir müzik yaratmak ve elektriksel sinyaller üretmek için kullanılan bir müzik aletidir. Synthesizer,amfilerden ses çıkarmak için elektriksel sinyalleri amfilere gönderir.
Bu devre MIDI bir klavye veya başka bir MIDI alet bağlanarakda kontrol edilebilir. Veya USB MIDI convertörler yardımıyla dijital müzikleri (MP3) çevirebilirsiniz.
İşte Malzeme Listemiz
1x TI Launchpad veya başka bir MSP430
1x 280 ohm direnç (yerine iç pull-up kullanabilirsiniz)
1x 220 ohm direnç
1x Sharp PC900V optokuplör
1x Hoparlör
1x MIDI dişi jack
1X diyot
Bir midi kablosu ve midi kontrolörü çeşit
Devre Şeması Ve Kodun Çalışma Felsefesi
Hoparlör GND ve LaunchPad'iin P1.2 ucuna bağlıdır. Bu arada, birden fazla launchpade veri göndermek için bir optokuplörlü devre kullanabilirsiniz. İşin özü şudur; TimerA MIDI formatında gelen veriyi alarak kare dalga biçimine dönüştürüp hoparlöre verir.
Kod:
#include "msp430g2231.h"
#define CLOCKHZ 16000000 / 8
#define nNotes 12
#define MIDI_DATA_PIN BIT7
#define SPEAKER_PIN BIT2
// Poly not implemented, but this is how
// many notes can be hit at the same time
// without forgetting the first
#define MAX_POLYPHONY 5
#define MIDI_CHANNEL 0 // MIDI is 1-indexed so setting this to 0 is midi channel 1
#define USI_COUNTER_LOAD 16
// Synth variables
unsigned int periodSetting = 61156;
const unsigned int synthNotes[nNotes] = {61156, 57723, 54484, 51424, 48539, 45817, 43245, 40816, 38527, 36364, 34322, 32396};
// MIDI Variables
char currentState = 1;
char bitStateCount = 0;
char nextBitFinal = 0;
char opcode;
char midiByte;
char rawMidiByte;
char newByte = 0;
char newVelocity;
char newNote;
char notes[MAX_POLYPHONY] = {0};
char velocities[MAX_POLYPHONY] = {0};
char controllerNumber;
char controllerValue;
int noteIndex = 0;
unsigned int USIData = 0;
void updateSynth(char on);
char getNextByte();
void updateState();
void noteOn();
void noteOff();
void controlChange();
void updateControls();
void shiftLeft(char index);
char getNoteIndex(char note);
void main(void)
{
volatile unsigned long i;
DCOCTL = CALDCO_16MHZ;
BCSCTL1 = CALBC1_16MHZ;
BCSCTL2 |= DIVS_2; // SMCLK = MCLK / 4 = 4MHZ
WDTCTL = WDTPW + WDTHOLD; // Stop WDT
_BIS_SR(GIE); // enable interrupts
P1DIR |= BIT2 + BIT0 + BIT6; // P1.2 and P1.3 output
P1OUT = 0;
CCTL1 = OUTMOD_7; // CCR1 reset/set
TACTL = TASSEL_2 + MC_1 + ID_3; // SMCLK, up mode, /8 = 500KHz
TACCTL0 |= CCIE;
CCR0 = 1;
USICKCTL |= USISSEL_3; // USI CLOCK SOURCE = SMCLK = 4MHZ
USICKCTL |= USIDIV_5;//5 // DIVIDES SMCLK BY 32 = 31250 * 4 = MIDI SPEC * 4x oversample
USICTL0 |= USIMST; // USE THE INTERNAL CLOCK
USICTL0 |= USIPE7; // ENABLE USI INPUT PORT 1.7
USICTL0 |= USILSB;
USICTL0 &= ~USISWRST; // START HARDWARE SERIAL RECIEVE
USICNT |= USI16B;
USICTL1 |= USIIE; // INTERRUPT WHEN SERIAL CACHE FULL
while(1){
opcode = getNextByte();
if(opcode == (0x90 | MIDI_CHANNEL))
noteOn();
else if(opcode == (0x80 | MIDI_CHANNEL))
noteOff();
else if(opcode == (0xB0 | MIDI_CHANNEL))
controlChange();
}
}
#pragma vector=USI_VECTOR
__interrupt void USI(){
USICNT |= USI_COUNTER_LOAD;
USIData = USISR;
char samplingBit;
for(samplingBit = 0; samplingBit < 16; samplingBit++){
if((USIData & BIT0) ^ currentState){ // if they're not the same
if(bitStateCount > 2){
rawMidiByte >>= 1;
if(currentState)
rawMidiByte |= BIT7;
if(nextBitFinal){
newByte = 1;
midiByte = rawMidiByte;
rawMidiByte = 0xFF;
nextBitFinal = 0;
}
}
currentState ^= BIT0;
bitStateCount = 1;
}
else{
bitStateCount++;
if(bitStateCount == 4){
rawMidiByte >>= 1;
if(currentState)
rawMidiByte |= BIT7;
if(nextBitFinal){
newByte = 1;
midiByte = rawMidiByte;
rawMidiByte = 0xFF;
nextBitFinal = 0;
}
bitStateCount = 0;
}
}
USIData >>= 1;
if(!newByte && (~rawMidiByte & BIT0))
nextBitFinal = 1;
}
}
void noteOn(){
do{
newNote = getNextByte();
if(newNote & 0x80){
newByte = 1;
break;
}
newVelocity = getNextByte();
if(newVelocity & 0x80){
newByte = 1;
break;
}
updateState();
}while(1);
}
void noteOff(){
do{
newNote = getNextByte();
if(newNote & 0x80){
newByte = 1;
break;
}
newVelocity = 0;
updateState();
}while(1);
}
void controlChange(){
do{
controllerNumber = getNextByte();
if(controllerNumber & 0x80){
newByte = 1;
break;
}
controllerValue = getNextByte();
if(controllerValue & 0x80){
newByte = 1;
break;
}
updateControls();
}while(1);
}
void updateControls(){
// stub
// if(controllerNumber == 1)
// do something with controllerValue
}
char getNextByte(){
char nextByte;
do{
P1OUT &= ~BIT0;
while(!newByte){
}
newByte = 0;
nextByte = midiByte;
}while((nextByte == 0xFE) || (nextByte == 0xFF));
P1OUT |= BIT0;
return nextByte;
}
#pragma vector=TIMERA0_VECTOR
__interrupt void Timer_A0 (void){
CCR0 = periodSetting;
CCR1 = (CCR0 >> 1);
}
void updateState(){
if(noteIndex == 0 && newVelocity != 0){
notes[0] = newNote;
velocities[0] = newVelocity;
updateSynth(1);
noteIndex++;
}
else{
if(newVelocity != 0){
// add a new note when the poly cache is full, replacing the oldest
if(MAX_POLYPHONY == noteIndex){
shiftLeft(0);
notes[MAX_POLYPHONY - 1] = newNote;
velocities[MAX_POLYPHONY - 1] = newVelocity;
updateSynth(1);
}
// add a new note
else{
notes[noteIndex] = newNote;
velocities[noteIndex] = newVelocity;
updateSynth(1);
noteIndex++;
}
}
else if(getNoteIndex(newNote) < MAX_POLYPHONY){
shiftLeft(getNoteIndex(newNote));
noteIndex -= 2;
if(noteIndex >= 0){
updateSynth(1);
noteIndex++;
}
else{
updateSynth(0);
noteIndex = 0;
}
}
}
}
void shiftLeft(char index){
int i;
for(i = index; i < MAX_POLYPHONY - 1; i++){
notes[i] = notes[i + 1];
velocities[i] = velocities[i + 1];
}
}
char getNoteIndex(char note){
int i;
for(i = 0; i < MAX_POLYPHONY; i++)
if(notes[i] == note)
return i;
return MAX_POLYPHONY + 1;
}
void updateSynth(char on){
if(on){
P1SEL |= 0x0C;
P1OUT |= BIT6;
}
else{
P1SEL &= ~0x0C;
P1OUT &= ~BIT6;
}
if(noteIndex >= 0 && noteIndex < MAX_POLYPHONY)
periodSetting = (synthNotes[notes[noteIndex] % 12] >> (notes[noteIndex] / 12));
}
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