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Running status support for the MIDI. Low frequency modulation of freq…
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…uency modulation support is added.
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@kehribar
kehribar committed Nov 1, 2015
1 parent e2f0ff4 commit 8a56095
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Showing 3 changed files with 119 additions and 116 deletions.
2 changes: 1 addition & 1 deletion _synth/lut.h
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Original file line number Diff line number Diff line change
Expand Up @@ -13,7 +13,7 @@ static const uint16_t noteToFreq[88] = {
3683, 3902, 4134, 4380, 4640, 4916, 5208, 5518
};

const int16_t sin_lut[1024] = {
static const int16_t sin_lut[1024] = {
0, 201, 402, 603, 804, 1005, 1206, 1406, 1607, 1808,
2009, 2209, 2410, 2610, 2811, 3011, 3211, 3411, 3611, 3811,
4011, 4210, 4409, 4608, 4807, 5006, 5205, 5403, 5601, 5799,
Expand Down
227 changes: 114 additions & 113 deletions _synth/main.c
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Original file line number Diff line number Diff line change
Expand Up @@ -21,17 +21,23 @@
#include "soft_uart.h"
#include "systick_delay.h"
/*---------------------------------------------------------------------------*/
#define MAX_VOICE 14
#define MAX_VOICE 10
#define BURST_SIZE 16
#define LOWPASS_ORDER 3
/*---------------------------------------------------------------------------*/
t_lfo outputLfo;
uint8_t midibuf[3];
uint8_t midibuf[2];
uint8_t argInd = 0;
int16_t g_cutoff = 0;
int16_t g_resonance = 0;
RingBuffer_t midi_ringBuf;
uint8_t runningCommand = 0;
uint16_t g_modFreq;
uint16_t g_maxModulation;
t_envSetting fmEnvSetting;
t_envSetting ampEnvSetting;
t_envSetting modEnvSetting;
int16_t * soundLut = sin_lut;
int16_t g_modulationIndex = 1;
struct t_key voice[MAX_VOICE];
uint8_t midi_ringBufData[1024];
Expand All @@ -45,8 +51,8 @@ static void midi_noteOffMessageHandler(const uint8_t note);
static inline int32_t convertDataForDma_24b(const int32_t data);
static void midi_controlMessageHandler(const uint8_t id, const uint8_t data);
static void midi_noteOnMessageHandler(const uint8_t note,const uint8_t velocity);
static inline int32_t fm_iterate(t_key* key, const int16_t depth_mod, const uint16_t depth_amp);
static int16_t envelope_iterate(t_envelope* env, const t_envSetting* setting, const uint16_t maxVal);
static int32_t fm_iterate(t_key* key, const int16_t depth_fm, const uint16_t depth_amp, const uint16_t depth_mod);
/*---------------------------------------------------------------------------*/
int main(void)
{
Expand Down Expand Up @@ -144,21 +150,26 @@ static int16_t envelope_iterate(t_envelope* env, const t_envSetting* setting, co
return output;
}
/*---------------------------------------------------------------------------*/
static inline int32_t fm_iterate(t_key* key, const int16_t depth_mod, const uint16_t depth_amp)
static inline int32_t fm_iterate(t_key* key, const int16_t depth_fm, const uint16_t depth_amp, const uint16_t depth_mod)
{
int16_t signal_mod;
int16_t signal_fm;
uint16_t signal_phase;

key->phaseCounterMod += key->freqMod;
key->phaseCounterFm += key->freqMod;
key->phaseCounterTone += key->freqTone;

signal_mod = sin_lut[key->phaseCounterMod >> 6];
signal_mod = S16S16MulShift8(signal_mod, depth_mod);
signal_fm = sin_lut[key->phaseCounterFm >> 6];
signal_fm = S16S16MulShift8(signal_fm, depth_fm);

signal_phase = key->phaseCounterTone;
signal_phase += signal_mod;
signal_phase += signal_fm;

key->phaseCounterMod += g_modFreq;
signal_mod = sin_lut[key->phaseCounterMod >> 6];
signal_phase += S16S16MulShift8(signal_mod, depth_mod);

return S16S16MulShift16(sin_lut[signal_phase >> 6], depth_amp);
return S16S16MulShift16(soundLut[signal_phase >> 6], depth_amp);
}
/*---------------------------------------------------------------------------*/
static inline void check_notes()
Expand All @@ -177,46 +188,44 @@ static inline void check_notes()
}
data = RingBuffer_Remove(&midi_ringBuf);
__enable_irq();

/* Sliding buffer ... */
midibuf[0] = midibuf[1];
midibuf[1] = midibuf[2];
midibuf[2] = data;

if((midibuf[1] < 128) && (midibuf[2] < 128))
{
/* Note on */
if((midibuf[0] & 0xF0) == 0x90)
{
/* If velocity is zero, treat it like 'note off' */
if(midibuf[2] == 0x00)
{
midi_noteOffMessageHandler(midibuf[1]);

if(data & 0x80)
{
argInd = 0;
runningCommand = data;
}
else
{
midibuf[argInd++] = data;
if(argInd == 2)
{
argInd = 0;

/* Note on */
if((runningCommand & 0xF0) == 0x90)
{
/* If velocity is zero, treat it like 'note off' */
if(midibuf[1] == 0x00)
{
midi_noteOffMessageHandler(midibuf[0]);
}
else
{
midi_noteOnMessageHandler(midibuf[0],midibuf[1]);
}
}
else
{
midi_noteOnMessageHandler(midibuf[1],midibuf[2]);
/* Note off */
else if((runningCommand & 0xF0) == 0x80)
{
midi_noteOffMessageHandler(midibuf[0]);
}
}
/* Note off */
else if((midibuf[0] & 0xF0) == 0x80)
{
midi_noteOffMessageHandler(midibuf[1]);
}
/* Control message */
else if((midibuf[0] & 0xF0) == 0xB0)
{
midi_controlMessageHandler(midibuf[1],midibuf[2]);
}
else
{
// ...
}
/* Control message */
else if((runningCommand & 0xF0) == 0xB0)
{
midi_controlMessageHandler(midibuf[0],midibuf[1]);
}
}
}
else
{
// ...
}
}

/* Scan voices */
Expand All @@ -225,21 +234,22 @@ static inline void check_notes()
/* Key down */
if((voice[i].noteState == NOTE_TRIGGER) && (voice[i].noteState_d != NOTE_TRIGGER))
{
voice[i].phaseCounterMod = 0;
voice[i].phaseCounterTone = 0;
voice[i].phaseCounterFm = 0;
voice[i].phaseCounterMod = 0;
voice[i].phaseCounterTone = 0;

/* Attack state */
voice[i].fmEnvelope.state = 1;
voice[i].ampEnvelope.state = 1;
voice[i].modEnvelope.state = 1;
voice[i].modEnvelope.state = 1;
voice[i].ampEnvelope.envelopeCounter= 0;
voice[i].modEnvelope.envelopeCounter = 0;

voice[i].maxModulation = voice[i].keyVelocity >> 8;
voice[i].modEnvelope.envelopeCounter = 0;
}
/* Key up */
else if((voice[i].noteState != NOTE_TRIGGER) && (voice[i].noteState_d == NOTE_TRIGGER))
{
/* Release state */
voice[i].fmEnvelope.state = 4;
voice[i].ampEnvelope.state = 4;
voice[i].modEnvelope.state = 4;
}
Expand All @@ -259,8 +269,9 @@ static inline void synth_loop(int32_t* const buf)

/* Deal with the initial voice first */
{
int16_t mod_amp = envelope_iterate(&(voice[0].modEnvelope),&modEnvSetting,voice[0].maxModulation);
int16_t sig_amp = envelope_iterate(&(voice[0].ampEnvelope),&ampEnvSetting,voice[0].keyVelocity);
int16_t fm_amp = envelope_iterate(&(voice[0].fmEnvelope),&fmEnvSetting,voice[0].maxModulation);
int16_t sig_amp = envelope_iterate(&(voice[0].ampEnvelope),&ampEnvSetting,voice[0].keyVelocity);
int16_t mod_amp = envelope_iterate(&(voice[0].modEnvelope),&modEnvSetting,g_maxModulation);

if(sig_amp == 0)
{
Expand All @@ -270,15 +281,16 @@ static inline void synth_loop(int32_t* const buf)

for(i=0;i<BURST_SIZE;i++)
{
outputBuffer[i] = fm_iterate(&(voice[0]),mod_amp,sig_amp);
outputBuffer[i] = fm_iterate(&(voice[0]),fm_amp,sig_amp,mod_amp);
}
}

/* Scan through other voices */
for(k=1;k<MAX_VOICE;k++)
{
int16_t mod_amp = envelope_iterate(&(voice[k].modEnvelope),&modEnvSetting,voice[k].maxModulation);
int16_t sig_amp = envelope_iterate(&(voice[k].ampEnvelope),&ampEnvSetting,voice[k].keyVelocity);
int16_t fm_amp = envelope_iterate(&(voice[k].fmEnvelope),&fmEnvSetting,voice[k].maxModulation);
int16_t sig_amp = envelope_iterate(&(voice[k].ampEnvelope),&ampEnvSetting,voice[k].keyVelocity);
int16_t mod_amp = envelope_iterate(&(voice[k].modEnvelope),&modEnvSetting,g_maxModulation);

if(sig_amp == 0)
{
Expand All @@ -288,7 +300,7 @@ static inline void synth_loop(int32_t* const buf)

for(i=0;i<BURST_SIZE;i++)
{
outputBuffer[i] += fm_iterate(&(voice[k]),mod_amp,sig_amp);
outputBuffer[i] += fm_iterate(&(voice[k]),fm_amp,sig_amp,mod_amp);
}
}

Expand Down Expand Up @@ -345,46 +357,18 @@ void USART1_IRQHandler()
{
USART1->ICR = 0xFFFFFFFF;
uint8_t data = usart1_readByte();
if(!RingBuffer_IsFull(&midi_ringBuf))
if((data != 0xF8) && (data != 0xFE))
{
RingBuffer_Insert(&midi_ringBuf,data);
if(!RingBuffer_IsFull(&midi_ringBuf))
{
RingBuffer_Insert(&midi_ringBuf,data);
}
}
}
/*---------------------------------------------------------------------------*/
static void midi_controlMessageHandler(const uint8_t id, const uint8_t data)
{
switch(id)
{
case 61:
{
g_cutoff = data * 2;
break;
}
case 62:
{
g_resonance = data * 2;
break;
}
case 63:
{
ampEnvSetting.attackRate = data * 16;
break;
}
case 102:
{
modEnvSetting.attackRate = data * 16;
break;
}
case 103:
{
g_modulationIndex = data * 16;
break;
}
default:
{
break;
}
}

}
/*---------------------------------------------------------------------------*/
static void midi_noteOnMessageHandler(const uint8_t note,const uint8_t velocity)
Expand All @@ -400,9 +384,10 @@ static void midi_noteOnMessageHandler(const uint8_t note,const uint8_t velocity)
if((voice[k].lastnote == 0) && (voice[k].noteState == NOTE_SILENT))
{
voice[k].freqTone = noteToFreq[note - 21];
voice[k].freqMod = S16S16MulShift8(voice[k].freqTone, g_modulationIndex);
voice[k].freqMod = S16S16MulShift8(voice[k].freqTone, g_modulationIndex);
voice[k].lastnote = note;
voice[k].keyVelocity = velocity * 512;
voice[k].keyVelocity = velocity * 512; // Change this to exponential scale?
voice[k].maxModulation = (voice[k].keyVelocity >> 7); // Change this to exponential scale?
voice[k].noteState = NOTE_TRIGGER;
return;
}
Expand Down Expand Up @@ -438,7 +423,7 @@ static void hardware_init()
systick_init(SYSTICK_1MS);

/* init uart and enable xprintf library */
usart1_init(115200);
usart1_init(31250);
xdev_out(usart1_sendChar);
usart1_enableReceiveISR();

Expand Down Expand Up @@ -504,34 +489,50 @@ static void hardware_init()
/* Small delay for general stabilisation */
_delay_ms(100);

/* Init the lowpass filter buffer */
for(i=0;i<BURST_SIZE;i++)
{
for(k=0;k<LOWPASS_ORDER+1;k++)
{
g_history[i][k] = 0;
}
}

g_modulationIndex = 256;

ampEnvSetting.attackRate = 2000;
modEnvSetting.attackRate = 5000;

ampEnvSetting.decayRate = 20;
modEnvSetting.decayRate = 20;

ampEnvSetting.sustainLevel = 4500;
modEnvSetting.sustainLevel = 4500;

ampEnvSetting.releaseRate = 50;
modEnvSetting.releaseRate = 50;
/* FM modulation freq vs Signal frequency ratio. Will get divided to 256 later */
g_modulationIndex = 128;

/* Output signal level amplitude envelope */
ampEnvSetting.attackRate = 4096;
ampEnvSetting.decayRate = 8;
ampEnvSetting.sustainLevel = 0;
ampEnvSetting.releaseRate = 64;

/* Timbre changing frequency modulation level envelope */
fmEnvSetting.attackRate = 4096;
fmEnvSetting.decayRate = 8;
fmEnvSetting.sustainLevel = 0;
fmEnvSetting.releaseRate = 64;

/* LFO rate frequency modulation envlope */
g_modFreq = 5;
g_maxModulation = 64;
modEnvSetting.attackRate = 16;
modEnvSetting.decayRate = 32;
modEnvSetting.sustainLevel = 0;
modEnvSetting.releaseRate = 10000;

/* Output signal panning and 'tremolo' effect */
outputLfo.freq = 3;
outputLfo.depth = 100;
outputLfo.phaseCounter_left = 0;
outputLfo.phaseCounter_right = 0;
outputLfo.stereoPanning_offset = 0x8000;

outputLfo.freq = 3;
outputLfo.depth = 150;
outputLfo.stereoPanning_offset = 0x8000;

/* Final output stage low pass parameters */
g_cutoff = 5;
g_resonance = 70;

soundLut = sin_lut;

xfprintf(dbg_sendChar,"> Hello World\r\n");
RingBuffer_InitBuffer(&midi_ringBuf, midi_ringBufData, sizeof(midi_ringBufData));
Expand Down
6 changes: 4 additions & 2 deletions _synth/synth.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -40,7 +40,9 @@ typedef struct t_key {
uint16_t freqTone;
uint16_t freqMod;
uint16_t phaseCounterTone;
uint16_t phaseCounterMod;
uint16_t phaseCounterMod;
uint16_t phaseCounterFm;
t_envelope fmEnvelope;
t_envelope modEnvelope;
t_envelope ampEnvelope;
t_envelope ampEnvelope;
} t_key;

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