Beat707 just released the open-source Beat707 SE - LE Version
http://www.beat707.com/forum/viewtopic.php?f=2&t=93
Beat707 8 x Voice Synth using no special hardware (LE version)
August 18 2011 - Version 1.0.0
First Release (8 voices with 4 modes + Draft Pitch Bend)
MIDI CC 0 = Mode / 0= 8 Voices / 1= 4 Voices Double Mode / 2= 2 Voices Double Mode + Octave Up / 3= 2 Voices Double Mode + Octave Up + Octave Down
MIDI CC 1 = PWM Rate-Fine (When PWM Rate-Coarse is 0, this will be PWM position instead)
MIDI CC 2 = PWM Rate-Coarse
MIDI CC 3 = Velocity to PWM Mode
Audio Examples: (pure raw output from the design)
http://www.beat707.com/downloads/Beat70 … _SY_LE.wav
or
http://www.beat707.com/downloads/Beat70 … _SY_LE.mp3
D4p0up
August 26, 2011, 8:49am
#2
Very nice sounds, good job though ! i've been working around DIY 8bit DACs and they have this particular "lowfi non-quality" that makes it sooo stylish.
Here’s the latest GitHub link:
https://github.com/Beat707/Beat707-SY-LE
/*
Created by Beat707 (c) 2011 - http://www.Beat707.com
August 18 2011 - Version 1.0.0
Requires the MIDI Shield:
http://www.ruggedcircuits.com/html/flexible_midi_shield.html
And 8 x 10k Resistors on each output, starting on digital output 2 ... 9 - connect all resistors to Left+Right of a Headphone or Line-Output, and Arduino-Ground to Output-Ground.
*/
#define MULT 65535
#define MULT2 (65535/2)
#define MTYPE unsigned int
#define MAX_V 8
#define SAMPLE_RATE 48048.048f
#define TIMER_ICR 333
#if defined(__AVR_ATmega1280__) || defined(__AVR_ATmega2560__)
# define MIDI_EN 57 // PF3 = 57
#else
# define MIDI_EN 17
#endif
MTYPE oscPos[MAX_V];
MTYPE oscRate[MAX_V];
MTYPE oscRateOriginal[MAX_V];;
MTYPE oscPWM = MULT2;
MTYPE freqTable[128];
uint8_t maxVoices = MAX_V;
uint8_t outPins = 0;
char pitchBend = 64;
uint8_t voiceNote[MAX_V];
uint8_t voiceOrder[MAX_V];
uint8_t voiceOrderCounter = 0;
uint8_t voiceActive[MAX_V];
uint8_t deviation = 1;
uint8_t deviationMode = 1;
uint8_t velocityMode = 0;
byte incomingByte;
byte note;
byte noteOn = 0;
byte state = 0;
// ======================================================================================= //
void setup()
{
memset(oscPos,0,sizeof(oscPos));
memset(oscRate,0,sizeof(oscRate));
memset(oscRateOriginal,0,sizeof(oscRateOriginal));
memset(voiceNote,0,sizeof(voiceNote));
memset(voiceOrder,0,sizeof(voiceOrder));
memset(voiceActive,0,sizeof(voiceActive));
double k = 1.059463094359; // Frequency (Hz) Table
double a = 6.875;
a *= k; a *= k; a *= k;
for (int i = 0; i < 128; i++)
{
freqTable[i] = (MTYPE) (MULT * (1.0f/SAMPLE_RATE) * a);
a *= k;
}
TCCR1A = _BV(WGM11);
TCCR1B = _BV(WGM12) | _BV(WGM13) | _BV(CS10);
ICR1 = TIMER_ICR-1;
pinMode(2, OUTPUT);
pinMode(3, OUTPUT);
pinMode(4, OUTPUT);
pinMode(5, OUTPUT);
pinMode(6, OUTPUT);
pinMode(7, OUTPUT);
pinMode(8, OUTPUT);
pinMode(9, OUTPUT);
TIMSK1 = _BV(TOIE1);
sei();
Serial.begin(31250);
pinMode(MIDI_EN, OUTPUT); digitalWrite(MIDI_EN, HIGH);
}
// ======================================================================================= //
uint8_t isDecay = 1;
uint8_t pwmModRate = 1;
uint8_t pwmModRateCounter = 0;
uint8_t pwmModAdder = 1;
#define calcOSC(a) oscPos[a] += oscRate[a]; if (voiceActive[a] == 1 && oscPos[a] < oscPWM) bitSet(outPins,a);
// ======================================================================================= //
ISR(TIMER1_OVF_vect)
{
PORTD = outPins; // Pins 0 to 7 //
PORTB = outPins; // Pins 8 to 13 //
outPins = 0;
calcOSC(0);
calcOSC(1);
calcOSC(2);
calcOSC(3);
calcOSC(4);
calcOSC(5);
calcOSC(6);
calcOSC(7);
if (pwmModAdder > 0)
{
pwmModRateCounter++;
if (pwmModRateCounter > pwmModRate)
{
pwmModRateCounter = 0;
if (isDecay == 1)
{
oscPWM -= pwmModAdder; if (oscPWM < (MULT2/100)) isDecay = 0;
}
else
{
oscPWM += pwmModAdder; if (oscPWM >= MULT2) isDecay = 1;
}
}
}
}
// ======================================================================================= //
void loop()
{
if (Serial.available() > 0)
{
incomingByte = Serial.read();
switch (state)
{
case 0:
if (incomingByte >= 128)
{
if (incomingByte <= 143) // Note Off //
{
noteOn = 0;
state = 1;
}
else if (incomingByte <= 159) // Note On //
{
noteOn = 1;
state = 1;
}
else if (incomingByte <= 191) // CC //
{
noteOn = 2; // Midi CC //
state = 1;
}
else if (incomingByte <= 239) // Bend //
{
noteOn = 3; // Pitch Bend //
state = 1;
}
}
break;
case 1:
if(incomingByte < 128) // Note Number //
{
note = incomingByte;
state = 2;
}
else state = 0; // reset //
break;
case 2:
if(incomingByte < 128) // Velocity //
{
if (noteOn == 1 && incomingByte > 0)
{
if (velocityMode == 1) oscPWM = 1000.0f+(((float)incomingByte/127.0f)*(MULT2-1000));
setNoteOn(note); // Note On //
}
else if (noteOn == 2) // Midi CC //
{
switch (note)
{
case 0: deviationMode = incomingByte/40; if (deviationMode > 3) deviationMode = 3; break;
case 1: if (pwmModAdder == 0) oscPWM = 1000.0f+(((float)incomingByte/127.0f)*(MULT2-1000)); else pwmModRate = (127-incomingByte)/4; break;
case 2: pwmModAdder = incomingByte/4; if (pwmModAdder == 0) oscPWM = MULT2; break;
case 3: velocityMode = (incomingByte > 64); if (velocityMode == 1) pwmModAdder = 0; break;
}
}
else if (noteOn == 3) // Pitch Bend //
{
pitchBend = incomingByte;
for (char w=0; w<MAX_V; w++) { oscRate[w] = oscRateOriginal[w]+((pitchBend-64)/2); }
}
else
{
setNoteOff(note); // Note Off //
}
noteOn = 0;
}
state = 0; // reset //
break;
}
}
}
// ======================================================================================= //
void setNoteOn(uint8_t note)
{
uint8_t voice = 255;
maxVoices = MAX_V;
if (deviationMode == 1) maxVoices = MAX_V/2;
if (deviationMode >= 2) maxVoices = MAX_V/4;
for (char v=0; v<maxVoices; v++)
{
if (voiceNote[v] == 0)
{
voice = v;
break;
}
}
// All voices used, steal oldest one //
if (voice == 255)
{
uint8_t order = 255;
for (char v=0; v<maxVoices; v++)
{
if (voiceOrder[v] < order)
{
order = voiceOrder[v];
voice = v;
}
}
}
// Store note //
voiceOrderCounter++;
voiceNote[voice] = note;
voiceOrder[voice] = voiceOrderCounter;
// Set Output //
oscRate[voice] = oscRateOriginal[voice] = freqTable[note];
voiceActive[voice] = 1;
if (deviationMode == 1)
{
deviation = 1;
if (note > 48) deviation = ((note-48)/4)+1;
oscRate[voice+4] = oscRateOriginal[voice+4] = oscRate[voice] + deviation;
voiceActive[voice+4] = 1;
}
else if (deviationMode == 2)
{
deviation = 1;
if (note > 48) deviation = ((note-48)/4)+1;
oscRate[voice+2] = oscRateOriginal[voice+2] = oscRate[voice] + deviation;
voiceActive[voice+2] = 1;
if ((note+12) > 127) note -= 12;
oscRate[voice+4] = oscRateOriginal[voice+4] = freqTable[note+12] + 1;
voiceActive[voice+4] = 1;
}
else if (deviationMode == 3)
{
deviation = 1;
if (note > 48) deviation = ((note-48)/4)+1;
oscRate[voice+2] = oscRateOriginal[voice+2] = oscRate[voice] + deviation;
voiceActive[voice+2] = 1;
if ((note+12) > 127) note -= 12;
oscRate[voice+4] = oscRateOriginal[voice+4] = freqTable[note+12] + 1;
voiceActive[voice+4] = 1;
if (((char)note-12) < 0) note += 12;
oscRate[voice+6] = oscRateOriginal[voice+6] = freqTable[note-12] + 1;
voiceActive[voice+6] = 1;
}
if (pitchBend != 64) { for (char w=0; w<MAX_V; w++) { oscRate[w] = oscRateOriginal[w]+((pitchBend-64)/2); } }
}
// ======================================================================================= //
void setNoteOff(uint8_t note)
{
uint8_t maxVoices = MAX_V;
if (deviationMode == 1) maxVoices = MAX_V/2;
if (deviationMode >= 2) maxVoices = MAX_V/4;
for (char v=0; v<maxVoices; v++)
{
if (voiceNote[v] == note)
{
voiceActive[v] = 0;
oscRate[v] = oscRateOriginal[v] = 0;
voiceNote[v] = 0;
if (deviationMode == 1)
{
voiceActive[v+4] = 0;
oscRate[v+4] = oscRateOriginal[v+4] = 0;
}
else if (deviationMode == 2)
{
voiceActive[v+2] = 0;
oscRate[v+2] = oscRateOriginal[v+2] = 0;
voiceActive[v+4] = 0;
oscRate[v+4] = oscRateOriginal[v+4] = 0;
}
else if (deviationMode == 3)
{
voiceActive[v+2] = 0;
oscRate[v+2] = oscRateOriginal[v+2] = 0;
voiceActive[v+6] = 0;
oscRate[v+6] = oscRateOriginal[v+6] = 0;
voiceActive[v+4] = 0;
oscRate[v+4] = oscRateOriginal[v+4] = 0;
}
break;
}
}
}
Interesting stuff.
Nothing beats sitting down in front of a real set tho ...
