eurorack/MIDI2CV.ino

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Arduino
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#include <MIDI.h>
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#include <SPI.h>
#include <DAC57X4.h>
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#include <EEPROM.h>
#define MIDI_CHANNEL 1
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#define OCTAVE_RANGE 10
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#define NOTE_RANGE (OCTAVE_RANGE * 12)
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#define MAX_CV 10.0
#define CV_PER_OCTAVE (MAX_CV / OCTAVE_RANGE)
#define BASE_NOTE 0
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// Define Pitch Bend range to be a major second
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#define BEND_RANGE ((CV_PER_OCTAVE / 12.0) * 1.5)
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#define PIN_GATE_0 A5
#define PIN_GATE_1 A1
#define PIN_GATE_2 A2
#define PIN_GATE_3 A3
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#define ROTARY_SWITCH_PIN0 2
#define ROTARY_SWITCH_PIN1 3
#define ROTARY_SWITCH_PIN2 4
#define ROTARY_SWITCH_PIN3 5
#define ROTARY_SWITCH_PIN4 6
#define ROTARY_SWITCH_PIN5 7
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#define PIN_SPEED A4
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#define PIN_FLIP_SWITCH_0 A6
#define PIN_FLIP_SWITCH_1 A7
#define FLIP_SWITCH_UP 0
#define FLIP_SWITCH_MIDDLE 1
#define FLIP_SWITCH_DOWN 2
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#define MODE_MONO 0
#define MODE_ARP 1
#define MODE_SEQ 2
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#define MIDI_CLOCK_THRESHOLD_MILLIS 500
#define MIDI_CLOCK_DIVIDE_QUARTER 24
#define MIDI_CLOCK_DIVIDE_HALF MIDI_CLOCK_DIVIDE_QUARTER * 2
#define MIDI_CLOCK_DIVIDE_WHOLE MIDI_CLOCK_DIVIDE_HALF * 2
#define MIDI_CLOCK_DIVIDE_EIGTH MIDI_CLOCK_DIVIDE_QUARTER / 2
#define MIDI_CLOCK_DIVIDE_EIGHT_T MIDI_CLOCK_DIVIDE_QUARTER / 3
#define MIDI_CLOCK_DIVIDE_SIXTEENTH MIDI_CLOCK_DIVIDE_EIGTH / 2
#define MIDI_CLOCK_DIVIDE_SIXTEENTH_T MIDI_CLOCK_DIVIDE_EIGTH / 3
#define MIDI_CLOCK_DIVIDE_THIRTY_SECOND MIDI_CLOCK_DIVIDE_SIXTEENTH / 2
#define MIDI_CLOCK_DIVIDE_THIRTY_SECOND_T MIDI_CLOCK_DIVIDE_SIXTEENTH / 3
#define MIDI_CLOCK_DIVISION_COUNT 9
const int clockDivisions[] = { MIDI_CLOCK_DIVIDE_WHOLE, MIDI_CLOCK_DIVIDE_HALF,
MIDI_CLOCK_DIVIDE_QUARTER,
MIDI_CLOCK_DIVIDE_EIGTH, MIDI_CLOCK_DIVIDE_EIGHT_T,
MIDI_CLOCK_DIVIDE_SIXTEENTH, MIDI_CLOCK_DIVIDE_SIXTEENTH_T,
MIDI_CLOCK_DIVIDE_THIRTY_SECOND, MIDI_CLOCK_DIVIDE_THIRTY_SECOND_T
};
#define MANUAL_CLOCK_MIN 20
#define MANUAL_CLOCK_MAX 2000
#define SEQUENCE_COUNT 6
#define SEQUENCE_LENGTH_MAX 128
#define ARP_DIRECTION_UP 0
#define ARP_DIRECTION_DOWN 1
#define ARP_DIRECTION_BOTH 2
#define ARP_DIRECTION_ORDER 3
#define ARP_DIRECTION_RANDOM 4
#define ARP_DIRECTION_NONE 5
#define ARP_MODE_LATCH FLIP_SWITCH_UP
#define ARP_MODE_FORGET FLIP_SWITCH_MIDDLE
#define ARP_MODE_ADD FLIP_SWITCH_DOWN
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DAC57X4 dac(4, 2, SS);
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MIDI_CREATE_DEFAULT_INSTANCE();
byte currentMode = MODE_MONO;
byte flipSwitch0 = FLIP_SWITCH_UP;
byte flipSwitch1 = FLIP_SWITCH_UP;
byte rotarySwitch = 0;
int speedValue = 0;
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float cv[] = {0, 0, 0, 0}; // 0 to MAX_CV
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bool gate[] = {LOW, LOW, LOW, LOW}; // LOW or HIGH
bool midiStartSignal = LOW;
bool midiClockSignal = LOW;
unsigned long activeNotes[NOTE_RANGE];
unsigned long noteCount = 1;
byte activeNoteCount = 0;
int currentPitchBend = 0;
byte currentModulation = 0;
byte currentVelocity = 0;
bool trigger = false;
bool released = false;
byte lastChannel = 0;
int clockCounter = 0;
unsigned long lastClockMillis = 0;
byte currentClockDivide = 0;
byte nextClockDivide = 0;
unsigned long lastManualClockMillis = 0;
byte currentSequencePosition = 0;
byte currentArpPosition = 0;
unsigned long activeArpNotes[NOTE_RANGE];
byte activeArpNoteCount = 0;
bool arpLatchReadyForNew = true;
void setup() {
pinMode(PIN_GATE_0, OUTPUT);
pinMode(PIN_GATE_1, OUTPUT);
pinMode(PIN_GATE_2, OUTPUT);
pinMode(PIN_GATE_3, OUTPUT);
MIDI.begin(MIDI_CHANNEL_OMNI);
MIDI.setHandleClock(onMidiClock);
MIDI.setHandleNoteOn(onMidiNoteOn);
MIDI.setHandleNoteOff(onMidiNoteOff);
MIDI.setHandleStart(onMidiStart);
MIDI.setHandleControlChange(onMidiControlChange);
MIDI.setHandlePitchBend(onMidiPitchBend);
}
void onMidiClock() {
if(clockCounter == 0) {
midiClockSignal = HIGH;
}
clockCounter++;
if(clockCounter == clockDivisions[currentClockDivide]) {
clockCounter = 0;
currentClockDivide = nextClockDivide;
}
lastClockMillis = millis();
}
void onMidiNoteOn(byte channel, byte note, byte velocity) {
if(channel > MIDI_CHANNEL + 1) return;
lastChannel = channel;
if(velocity == 0) { onMidiNoteOff(channel, note, velocity); return; }
activeNotes[note - BASE_NOTE] = noteCount++;
activeNoteCount++;
currentVelocity = velocity;
trigger = true;
}
void onMidiNoteOff(byte channel, byte note, byte velocity) {
if(channel > MIDI_CHANNEL + 1) return;
activeNotes[note - BASE_NOTE] = 0;
activeNoteCount--;
if(activeNoteCount == 0) currentVelocity = 0;
released = 0;
}
void onMidiControlChange(byte channel, byte number, byte value) {
if(channel > MIDI_CHANNEL + 1) return;
currentModulation = value;
}
void onMidiPitchBend(byte channel, int bend) {
if(channel > MIDI_CHANNEL + 1) return;
currentPitchBend = bend;
}
void onMidiStart() {
midiStartSignal = HIGH;
clockCounter = 0;
currentClockDivide = nextClockDivide;
}
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float midiToCV(byte note) {
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if(note < BASE_NOTE) return 0;
if(note - BASE_NOTE > NOTE_RANGE) return MAX_CV;
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return mapfloat(note - BASE_NOTE, 0, NOTE_RANGE, 0, MAX_CV);
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}
byte getMostRecentNote() {
byte note;
unsigned long maxTime = 0;
for(byte i = 0; i < NOTE_RANGE; i++) {
if(activeNotes[i] != 0 && activeNotes[i] >= maxTime) {
note = i;
maxTime = activeNotes[i];
}
}
return note;
}
void loop() {
readSwitches();
if(flipSwitch0 == FLIP_SWITCH_UP) currentMode = MODE_MONO;
else if(flipSwitch0 == FLIP_SWITCH_MIDDLE) currentMode = MODE_SEQ;
else if(flipSwitch0 == FLIP_SWITCH_DOWN) currentMode = MODE_ARP;
readSpeed();
MIDI.read();
if(millis() - lastClockMillis > MIDI_CLOCK_THRESHOLD_MILLIS) {
// Apparently we are not getting any midi clocks, so we will just generate our own signal.
long waitTime = map(speedValue, 0, 1023, (60000) / MANUAL_CLOCK_MIN, (60000) / MANUAL_CLOCK_MAX);
if(millis() - lastManualClockMillis > waitTime) {
// Time for another clock signal!
lastManualClockMillis = millis();
midiClockSignal = HIGH;
}
} else {
nextClockDivide = map(speedValue, 0, 1023, 0, MIDI_CLOCK_DIVISION_COUNT);
}
bool triggerOut = false;
switch(currentMode) {
case MODE_MONO:
if(activeNoteCount > 0) {
// Find most recent hit key
byte note = getMostRecentNote();
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float value = midiToCV(note + BASE_NOTE);
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cv[0] = value + mapfloat(currentPitchBend, 0, MIDI_PITCHBEND_MAX, -BEND_RANGE, BEND_RANGE);
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cv[1] = mapfloat(currentVelocity, 0, 127, 0, MAX_CV);
cv[2] = mapfloat(currentModulation, 0, 127, 0, MAX_CV);
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triggerOut = trigger;
if(lastChannel == MIDI_CHANNEL + 1 && trigger) { // IF on second channel, we retrigger the gate.
gate[0] = LOW;
} else {
gate[0] = HIGH;
}
} else {
gate[0] = LOW;
}
break;
case MODE_SEQ:
if(flipSwitch1 == FLIP_SWITCH_UP) {
// Rec mode.
if(activeNoteCount > 0) {
// Find most recent hit key
byte note = getMostRecentNote();
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float value = midiToCV(note + BASE_NOTE);
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cv[0] = value + mapfloat(currentPitchBend, 0, MIDI_PITCHBEND_MAX, -BEND_RANGE, BEND_RANGE);
gate[0] = HIGH;
if(trigger) {
triggerOut = true;
EEPROM.update(rotarySwitch, EEPROM[rotarySwitch] + 1);
byte notePosition = EEPROM[rotarySwitch] - 1;
EEPROM.update(SEQUENCE_COUNT + rotarySwitch * SEQUENCE_LENGTH_MAX + notePosition, note);
}
} else {
gate[0] = LOW;
triggerOut = false;
}
} else if(flipSwitch1 == FLIP_SWITCH_MIDDLE) {
// Play Mode
if(activeNoteCount > 0 && EEPROM[rotarySwitch] > 0) {
byte note = getMostRecentNote();
byte currentSequenceValue = EEPROM[SEQUENCE_COUNT + rotarySwitch * SEQUENCE_LENGTH_MAX + currentSequencePosition];
note = currentSequenceValue + note - EEPROM[SEQUENCE_COUNT + rotarySwitch * SEQUENCE_LENGTH_MAX + 0];
if(trigger && millis() - lastClockMillis > MIDI_CLOCK_THRESHOLD_MILLIS) {
// no midi input but a key was pressed, so we start the sequence now instead of at next clock signal
midiClockSignal = HIGH;
lastManualClockMillis = millis();
}
if(midiClockSignal) { // trigger a new note!
triggerOut = true;
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float value = midiToCV(note + BASE_NOTE);
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cv[0] = value + mapfloat(currentPitchBend, 0, MIDI_PITCHBEND_MAX, -BEND_RANGE, BEND_RANGE);
currentSequencePosition = (currentSequencePosition + 1) % EEPROM[rotarySwitch];
}
gate[0] = HIGH;
} else {
gate[0] = LOW;
currentSequencePosition = 0;
}
} else if(flipSwitch1 == FLIP_SWITCH_DOWN) {
// clear on note
if(activeNoteCount > 0 && trigger) {
EEPROM.update(rotarySwitch, 0);
}
}
break;
case MODE_ARP:
if(flipSwitch1 == ARP_MODE_LATCH) {
// ARP Mode LATCH
if(trigger) {
if(activeNoteCount == 1) {
// first note of the new arpeggio pressed
currentArpPosition = 0;
activeArpNoteCount = 1;
for(int i = 0; i < NOTE_RANGE; i++) {
if(activeNotes[i] != 0) currentArpPosition = i; // This is the first note of our arpeggio, so set it to this
activeArpNotes[i] = activeNotes[i];
}
} else {
// new note for current arpeggio
for(int i = 0; i < NOTE_RANGE; i++) {
if(activeNotes[i] != 0 && activeArpNotes[i] == 0) activeArpNoteCount++;
if(activeNotes[i] != 0) // We don't want to disable any notes, only activate new ones
activeArpNotes[i] = activeNotes[i];
}
}
}
} else if(flipSwitch1 == ARP_MODE_FORGET) {
// activeArpNotes is equivalent to activeNotes. ezpz
for(int i = 0; i < NOTE_RANGE; i++) {
activeArpNotes[i] = activeNotes[i];
}
activeArpNoteCount = activeNoteCount;
if(released && activeNoteCount == 0) {
currentArpPosition = 0;
}
} else if(flipSwitch1 == ARP_MODE_ADD) {
// we just add any active Note until some mysterious signal tells us to reset (modulation > 63!)
if(currentModulation < 64) {
byte active = 0;
for(int i = 0; i < NOTE_RANGE; i++) {
if(activeNotes[i] > 0) {
activeArpNotes[i] = activeNotes[i];
}
if(activeArpNotes[i] != 0)
active++;
}
activeArpNoteCount = active;
} else {
activeArpNoteCount = 0;
for(int i = 0; i < NOTE_RANGE; i++)
activeArpNotes[i] = 0;
}
}
if(activeArpNoteCount > 0) {
if( activeArpNotes[currentArpPosition] == 0) {
// find the first note in the arp.
switch(rotarySwitch) {
case ARP_DIRECTION_UP:
case ARP_DIRECTION_BOTH:
for(int i = 0; i < NOTE_RANGE; i++)
if(activeArpNotes[i] != 0) {
currentArpPosition = i;
break;
}
break;
case ARP_DIRECTION_DOWN:
for(int i = NOTE_RANGE - 1; i >= 0; i--)
if(activeArpNotes[i] != 0) {
currentArpPosition = i;
break;
}
break;
case ARP_DIRECTION_RANDOM:
byte newIndex = 0;
do {
newIndex = random(0, 255);
} while(activeArpNotes[newIndex] == 0 || currentArpPosition == newIndex);
currentArpPosition = newIndex;
break;
case ARP_DIRECTION_ORDER:
byte minValue = 0;
byte minValueIndex = 0;
for(int i = 0; i < NOTE_RANGE; i++) {
if(i == currentArpPosition || activeArpNotes[i] == 0) continue;
if(activeArpNotes[i] < minValue) {
minValue = activeArpNotes[i];
minValueIndex = i;
}
}
currentArpPosition = minValueIndex;
break;
}
}
byte note = currentArpPosition; // This is the current Arp Note to play
if(midiClockSignal) { // trigger a new note!
triggerOut = true;
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float value = midiToCV(note + BASE_NOTE);
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cv[0] = value + mapfloat(currentPitchBend, 0, MIDI_PITCHBEND_MAX, -BEND_RANGE, BEND_RANGE);
// now we have to find the next arp position. this depends on the current mode.
bool foundNote = false;
switch(rotarySwitch) {
case ARP_DIRECTION_UP:
if(activeArpNoteCount == 1) break;
// We just go up and if we reach the last note in the arp, we go back to the first one
for(int i = currentArpPosition + 1; i < NOTE_RANGE; i++) {
if(activeArpNotes[i] != 0) {
// found the next note!
currentArpPosition = i;
foundNote = true;
break;
}
}
if(!foundNote) {
// We have to find the first note at the beginning of the arpeggio now...
for(int i = 0; i < NOTE_RANGE; i++) {
if(activeArpNotes[i] != 0) {
// found the next note!
currentArpPosition = i;
break;
}
}
}
break;
case ARP_DIRECTION_DOWN:
if(activeArpNoteCount == 1) break;
// We just go down and if we reach the first note in the arp, we go forward to the last one
for(int i = currentArpPosition - 1; i >= 0; i--) {
if(activeArpNotes[i] != 0) {
// found the next note!
currentArpPosition = i;
foundNote = true;
break;
}
}
if(!foundNote) {
// We have to find the last note at the beginning of the arpeggio now...
for(int i = NOTE_RANGE - 1; i >= 0; i--) {
if(activeArpNotes[i] != 0) {
// found the next note!
currentArpPosition = i;
break;
}
}
}
break;
case ARP_DIRECTION_BOTH:
if(activeArpNoteCount == 1) break;
// We just go up and if we reach the last note in the arp, we go back one note
for(int i = currentArpPosition + 1; i < NOTE_RANGE; i++) {
if(activeArpNotes[i] != 0) {
// found the next note!
currentArpPosition = i;
foundNote = true;
break;
}
}
// we are going downwards, so let's search!
if(!foundNote) {
for(int i = currentArpPosition - 1; i >= 0; i--) {
if(activeArpNotes[i] != 0) {
// found the next note!
currentArpPosition = i;
foundNote = true;
break;
}
}
}
break;
case ARP_DIRECTION_ORDER:
if(activeArpNoteCount == 1) break;
// We find the note that has the least distance to the current notes value.
// If we can't find one, we assign the note with the lowest value
byte minValue = 255;
byte minValueIndex = 0;
for(int i = 0; i < NOTE_RANGE; i++) {
if(i == currentArpPosition || activeArpNotes[i] == 0) continue;
byte distance = abs(activeArpNotes[i] - activeArpNotes[currentArpPosition]);
if(distance < minValue) {
minValue = distance;
minValueIndex = i;
}
}
if(minValue == 255) { // We did not find a higher note, so let's go back to the first one.
minValue = 0;
for(int i = 0; i < NOTE_RANGE; i++) {
if(i == currentArpPosition || activeArpNotes[i] == 0) continue;
if(activeArpNotes[i] < minValue) {
minValue = activeArpNotes[i];
minValueIndex = i;
}
}
}
currentArpPosition = minValueIndex;
break;
case ARP_DIRECTION_RANDOM:
byte newIndex = 0;
do {
newIndex = random(0, 255);
} while(activeArpNotes[newIndex] == 0 || currentArpPosition == newIndex);
currentArpPosition = newIndex;
break;
case ARP_DIRECTION_NONE:
// Noone knows what happens here.
break;
}
}
gate[0] = HIGH;
} else {
gate[0] = LOW;
currentArpPosition = 0;
}
break;
}
gate[1] = triggerOut ? HIGH : LOW;
gate[2] = midiStartSignal;
gate[3] = midiClockSignal;
trigger = false;
released = false;
midiStartSignal = LOW;
midiClockSignal = LOW;
writeDACs();
writeGates();
}
float mapfloat(float x, float in_min, float in_max, float out_min, float out_max)
{
return (x - in_min) * (out_max - out_min) / (in_max - in_min) + out_min;
}
void readSwitches() {
int analogValue = analogRead(PIN_FLIP_SWITCH_0);
if(analogValue < 100) flipSwitch0 = FLIP_SWITCH_UP;
else if(analogValue < 900) flipSwitch0 = FLIP_SWITCH_DOWN;
else flipSwitch0 = FLIP_SWITCH_MIDDLE;
analogValue = analogRead(PIN_FLIP_SWITCH_1);
if(analogValue < 100) flipSwitch1 = FLIP_SWITCH_UP;
else if(analogValue < 900) flipSwitch1 = FLIP_SWITCH_DOWN;
else flipSwitch1 = FLIP_SWITCH_MIDDLE;
if(digitalRead(ROTARY_SWITCH_PIN0) == LOW) rotarySwitch = 0;
else if(digitalRead(ROTARY_SWITCH_PIN1) == LOW) rotarySwitch = 1;
else if(digitalRead(ROTARY_SWITCH_PIN2) == LOW) rotarySwitch = 2;
else if(digitalRead(ROTARY_SWITCH_PIN3) == LOW) rotarySwitch = 3;
else if(digitalRead(ROTARY_SWITCH_PIN4) == LOW) rotarySwitch = 4;
else if(digitalRead(ROTARY_SWITCH_PIN5) == LOW) rotarySwitch = 5;
}
void readSpeed() {
speedValue = analogRead(PIN_SPEED);
}
void writeDACs() {
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dac.SetDAC(cv[0], 1);
dac.SetDAC(cv[1], 2);
dac.SetDAC(cv[2], 3);
dac.SetDAC(cv[3], 4);
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}
void writeGates() {
digitalWrite(PIN_GATE_0, gate[0] == HIGH ? LOW : HIGH);
digitalWrite(PIN_GATE_1, gate[1] == HIGH ? LOW : HIGH);
digitalWrite(PIN_GATE_2, gate[2] == HIGH ? LOW : HIGH);
digitalWrite(PIN_GATE_3, gate[3] == HIGH ? LOW : HIGH);
}