Air Theremin

// Air theremin: move your hand over the ultrasonic sensor and the sound slides// smoothly up and down, like a real theremin. Closer = higher, farther = lower,// with a gentle wobble (vibrato). Take your hand away and it goes quiet.//   Playing area: about 2 inches (highest) to 20 inches (lowest) from the sensor.//// It also has the old air-piano mode (8 separate notes, C to high C, 2 inches// each). Switch from the computer with "t" (theremin) or "p" (piano).//// Wiring (same as the air piano):// Ultrasonic sensor (HC-SR04), 4 female-to-male wires://   Vcc -> 5V     Trig -> pin 8     Echo -> pin 7     Gnd -> GND//   (Trig and Echo can go in 7 and 8 either way round, the program checks.)// Buzzer (the starter kit's passive one, no sticker), 2 female-to-male wires://   one leg -> pin 13, the other leg -> the GND right next to pin 13.//   The board's "L" light flickers along with the sound.// Screen (LCD1602), optional, same pinout as the distance meter://    1 VSS -> GND         2 VDD -> A0          3 V0 -> pin 9       4 RS -> pin 12//    5 RW  -> A1          6 E   -> pin 11      7 to 10 -> nothing//   11 D4  -> pin 5      12 D5  -> pin 4      13 D6 -> pin 3      14 D7 -> pin 2//   15 A   -> pin 10     16 K   -> A2//// From the computer://   "t"      theremin mode          "p"      piano mode//   "m"      mute / unmute          "?"      sensor status//   "f"      blink the "L" light 3 times (to find this board)//   "c 40"   screen contrast        "b 160"  screen backlight// Mode, mute, contrast and backlight are saved.#include <EEPROM.h>// ---------- Pins ----------const byte SENSOR_PINS[2] = {7, 8};byte trigPin = 8;byte echoPin = 7;const byte BUZZER = 13;const byte LCD_POWER = A0;const byte LCD_RW = A1;const byte LCD_GROUND = A2;  // the backlight's K pinconst byte LCD_RS = 12;const byte LCD_E = 11;const byte LCD_DATA[4] = {5, 4, 3, 2};  // the screen's D4, D5, D6, D7const byte LCD_CONTRAST = 9;const byte LCD_LIGHT = 10;// ---------- Theremin sound ----------const float NEAREST_IN = 2.0;      // hand this close = highest pitchconst float FARTHEST_IN = 20.0;    // hand this far = lowest pitch (past it = quiet)const float LOWEST_HZ = 500.0;     // the little buzzer gets very quiet below thisconst float HIGHEST_HZ = 2500.0;   // about 2 1/3 octaves above the lowestconst float GLIDE = 0.25;          // how quickly the pitch slides to where your hand isconst float VIBRATO_DEPTH = 0.012; // wobble of about 1.2% up and downconst float VIBRATO_PER_SEC = 5.5; // wobbles per secondconst unsigned long SOUND_STEP_MS = 5;  // update the pitch 200 times a second// ---------- Piano notes ----------const byte NOTE_COUNT = 8;const char NOTE_NAMES[NOTE_COUNT] = {'C', 'D', 'E', 'F', 'G', 'A', 'B', 'C'};const unsigned int NOTE_HZ[NOTE_COUNT] = {1047, 1175, 1319, 1397, 1568, 1760, 1976, 2093};const float FIRST_NOTE_AT = 2.0;  // inches where the first C startsconst float NOTE_WIDTH = 2.0;     // inches per noteconst float WOBBLE = 0.4;         // a hand has to move this far past a line to change noteconst int NO_NOTE = -1;// ---------- Measuring ----------const float MICROS_PER_INCH = 148.0;       // sound out and back, per inchconst unsigned long LISTEN_MICROS = 4500;  // stop listening after ~30 inchesconst unsigned long PING_GAP_MS = 28;      // short rest so old echoes die awayconst unsigned long QUIET_AFTER_MS = 150;  // hand gone this long = quiet// ---------- Saved settings ----------const byte MODE_THEREMIN = 0;const byte MODE_PIANO = 1;struct Settings {  byte check;  byte contrast;  byte backlight;  byte muted;  byte mode;};const byte SETTINGS_CHECK = 0xA9;  // same as the air piano, so its screen settings carry overSettings settings;// ---------- What's happening now ----------float recent[3] = {0, 0, 0};  // last 3 readings, so one stray echo can't jump the soundbyte recentNext = 0;byte recentCount = 0;float hand = 0;               // the hand's distance (middle of the last 3), 0 = no handfloat lastHandInches = 0;     // the last real distance, for the computer readoutunsigned long lastHandSeen = 0;unsigned long lastPing = 0;bool sounding = false;        // theremin: is it making soundfloat targetHz = 0;           // theremin: where the pitch is headingfloat currentHz = 0;          // theremin: where the pitch is nowunsigned long lastSoundStep = 0;unsigned long lastScreen = 0;unsigned long lastReport = 0;int playing = NO_NOTE;        // piano: the note being playedvoid setup() {  Serial.begin(9600);  Serial.println("Theremin starting");  EEPROM.get(0, settings);  if (settings.check != SETTINGS_CHECK) {    settings = {SETTINGS_CHECK, 40, 160, 0, MODE_THEREMIN};  }  if (settings.mode > MODE_PIANO) settings.mode = MODE_THEREMIN;  // first time after the air piano  if (settings.muted > 1) settings.muted = 0;  EEPROM.put(0, settings);  // Pins 9 and 10 flicker very fast (31,000 times a second) to set the screen's  // contrast and brightness without it shimmering.  TCCR1B = (TCCR1B & 0b11111000) | 0b001;  pinMode(LCD_CONTRAST, OUTPUT);  pinMode(LCD_LIGHT, OUTPUT);  analogWrite(LCD_CONTRAST, settings.contrast);  analogWrite(LCD_LIGHT, settings.backlight);  pinMode(LCD_RW, OUTPUT);  digitalWrite(LCD_RW, LOW);  pinMode(LCD_GROUND, OUTPUT);  digitalWrite(LCD_GROUND, LOW);  pinMode(LCD_POWER, OUTPUT);  digitalWrite(LCD_POWER, HIGH);  delay(100);  lcdBegin();  makeNoteSymbol();  pinMode(BUZZER, OUTPUT);  findSensorPins();  playStartSound();  showIdle();  printMode();}void loop() {  readComputer();  unsigned long now = millis();  if (now - lastPing >= PING_GAP_MS) {    lastPing = now;    measureHand();    if (settings.mode == MODE_PIANO) pianoAfterPing();    else thereminAfterPing();  }  if (settings.mode == MODE_THEREMIN && now - lastSoundStep >= SOUND_STEP_MS) {    lastSoundStep = now;    thereminSoundStep(now);  }}// ---------- Measuring ----------// One ping, then "hand" = the middle of the last 3 good readings (or 0).void measureHand() {  float inches = readInches();  if (inches > 0) {    recent[recentNext] = inches;    recentNext = (recentNext + 1) % 3;    if (recentCount < 3) recentCount++;  } else {    findSensorPins();  // in case the wires were swapped or plugged in late  }  hand = (inches > 0 && recentCount >= 3) ? middleOf3() : 0;}// Works out which of pins 7 and 8 is Echo: with a pull-up on, the Echo pin// still reads LOW because the sensor holds it there; the Trig pin reads HIGH.void findSensorPins() {  pinMode(SENSOR_PINS[0], INPUT_PULLUP);  pinMode(SENSOR_PINS[1], INPUT_PULLUP);  delayMicroseconds(500);  bool low0 = digitalRead(SENSOR_PINS[0]) == LOW;  bool low1 = digitalRead(SENSOR_PINS[1]) == LOW;  if (low0 != low1) {    echoPin = low0 ? SENSOR_PINS[0] : SENSOR_PINS[1];    trigPin = low0 ? SENSOR_PINS[1] : SENSOR_PINS[0];  }  pinMode(echoPin, INPUT);  pinMode(trigPin, OUTPUT);  digitalWrite(trigPin, LOW);}// One ping. Returns the distance in inches, or 0 if nothing answered within ~30 in.float readInches() {  digitalWrite(trigPin, LOW);  delayMicroseconds(2);  digitalWrite(trigPin, HIGH);  delayMicroseconds(10);  digitalWrite(trigPin, LOW);  unsigned long microseconds = pulseIn(echoPin, HIGH, LISTEN_MICROS);  return microseconds == 0 ? 0 : microseconds / MICROS_PER_INCH;}float middleOf3() {  float a = recent[0], b = recent[1], c = recent[2];  if ((a <= b && b <= c) || (c <= b && b <= a)) return b;  if ((b <= a && a <= c) || (c <= a && a <= b)) return a;  return c;}// ---------- Theremin ----------// Turns a hand distance into a pitch. Equal hand movements give equal musical// steps, so the whole range feels even (like a real theremin).float pitchFor(float inches) {  float t = (FARTHEST_IN - inches) / (FARTHEST_IN - NEAREST_IN);  // 0 far ... 1 near  t = constrain(t, 0.0, 1.0);  return LOWEST_HZ * pow(HIGHEST_HZ / LOWEST_HZ, t);}void thereminAfterPing() {  if (hand > 0 && hand <= FARTHEST_IN) {    lastHandSeen = millis();    lastHandInches = hand;    targetHz = pitchFor(hand);    if (!sounding) {      sounding = true;      currentHz = targetHz;  // start right where the hand is, no swoop from the last note    }  } else if (sounding && millis() - lastHandSeen > QUIET_AFTER_MS) {    sounding = false;    noTone(BUZZER);    digitalWrite(BUZZER, LOW);    recentCount = 0;    showIdle();    Serial.println("Quiet");  }}// 200 times a second: slide toward the hand's pitch, add the wobble, play it.void thereminSoundStep(unsigned long now) {  if (!sounding) return;  currentHz += (targetHz - currentHz) * GLIDE;  float wobble = 1.0 + VIBRATO_DEPTH * sin(TWO_PI * VIBRATO_PER_SEC * now / 1000.0);  if (!settings.muted) tone(BUZZER, (unsigned int)(currentHz * wobble));  if (now - lastScreen >= 150) {    lastScreen = now;    showPitch(currentHz);  }  if (now - lastReport >= 400) {    lastReport = now;    Serial.print((int)currentHz);    Serial.print(" Hz  at ");    Serial.print(lastHandInches, 1);    Serial.println(" in");  }}// ---------- Piano ----------void pianoAfterPing() {  int note = (hand > 0) ? pickNote(hand) : NO_NOTE;  if (note != NO_NOTE) {    lastHandSeen = millis();    if (note != playing) startNote(note);  } else if (playing != NO_NOTE && millis() - lastHandSeen > QUIET_AFTER_MS) {    playing = NO_NOTE;    noTone(BUZZER);    digitalWrite(BUZZER, LOW);    recentCount = 0;    showIdle();    Serial.println("Quiet");  }}// Distance -> note number (0 = low C ... 7 = high C), or NO_NOTE. Near a line// between two notes it keeps the current note, so it doesn't flutter.int pickNote(float inches) {  if (playing != NO_NOTE) {    float low = FIRST_NOTE_AT + playing * NOTE_WIDTH - WOBBLE;    float high = FIRST_NOTE_AT + (playing + 1) * NOTE_WIDTH + WOBBLE;    if (inches >= low && inches < high) return playing;  }  if (inches < FIRST_NOTE_AT) return NO_NOTE;  int note = (int)((inches - FIRST_NOTE_AT) / NOTE_WIDTH);  return note < NOTE_COUNT ? note : NO_NOTE;}void startNote(int note) {  playing = note;  if (!settings.muted) tone(BUZZER, NOTE_HZ[note]);  showNote(note);  Serial.print("Note ");  Serial.print(NOTE_NAMES[note]);  if (note == NOTE_COUNT - 1) Serial.print(" (high)");  Serial.print("  at ");  Serial.print(hand, 1);  Serial.println(" in");}// ---------- Sounds ----------void playStartSound() {  if (settings.muted) return;  if (settings.mode == MODE_PIANO) {    const byte tune[] = {0, 2, 4, 7};    for (byte i = 0; i < sizeof(tune); i++) {      tone(BUZZER, NOTE_HZ[tune[i]], 110);      delay(140);    }  } else {    // A spooky swoop up and back down.    for (int i = 0; i <= 60; i++) {      tone(BUZZER, (unsigned int)pitchFor(FARTHEST_IN - i * 0.3));      delay(8);    }    for (int i = 60; i >= 0; i--) {      tone(BUZZER, (unsigned int)pitchFor(FARTHEST_IN - i * 0.3));      delay(5);    }  }  noTone(BUZZER);  digitalWrite(BUZZER, LOW);}void stopAllSound() {  noTone(BUZZER);  digitalWrite(BUZZER, LOW);  sounding = false;  playing = NO_NOTE;  recentCount = 0;}void printMode() {  Serial.print(settings.mode == MODE_PIANO ? "Ready: piano mode" : "Ready: theremin mode");  Serial.println(settings.muted ? " (muted)" : "");}// ---------- Screen ----------// The music note lives in the screen's custom character slot 0. The screen// shows slot 0 for code 0 or code 8; using 8 keeps it from ending the text.const byte NOTE_SYMBOL_SLOT = 0;const char NOTE_SYMBOL = 8;void showIdle() {  lcdWake();  if (settings.mode == MODE_PIANO) {    lcdPrintRow(0, settings.muted ? " Air Piano  mute" : "   Air Piano");    lcdPrintRow(1, "Hand 2-18in away");  } else {    lcdPrintRow(0, settings.muted ? " Theremin  mute" : "    Theremin");    lcdPrintRow(1, "Hand 2-20in away");  }}//   top row:     ♪  1234 Hz  ♪//   bottom row:  a bar that grows as the pitch goes upvoid showPitch(float hz) {  char top[17];  snprintf(top, sizeof(top), "  %c  %4d Hz  %c", NOTE_SYMBOL, (int)hz, NOTE_SYMBOL);  char bar[17];  float t = log(hz / LOWEST_HZ) / log(HIGHEST_HZ / LOWEST_HZ);  // 0 lowest ... 1 highest  int blocks = constrain((int)(t * 16 + 0.5), 1, 16);  for (byte i = 0; i < 16; i++) bar[i] = (i < blocks) ? (char)0xFF : ' ';  bar[16] = '\0';  lcdWake();  lcdPrintRow(0, top);  lcdPrintRow(1, bar);}//   top row:     ♪  E  ♪//   bottom row:  C D E F G A B C   with a solid block on the note being playedvoid showNote(int note) {  char top[17] = "                ";  top[4] = NOTE_SYMBOL;  top[11] = NOTE_SYMBOL;  top[7] = NOTE_NAMES[note];  if (note == NOTE_COUNT - 1) top[8] = '\'';  // high C  char row[17];  for (byte i = 0; i < NOTE_COUNT; i++) {    row[i * 2] = ' ';    row[i * 2 + 1] = (i == note) ? (char)0xFF : NOTE_NAMES[i];  }  row[16] = '\0';  lcdWake();  lcdPrintRow(0, top);  lcdPrintRow(1, row);}// A little music note, drawn dot by dot (5 wide, 8 tall).void makeNoteSymbol() {  const byte rows[8] = {    0b00100, 0b00110, 0b00101, 0b00100,    0b00100, 0b01100, 0b11100, 0b01000,  };  lcdSend(0x40 | (NOTE_SYMBOL_SLOT << 3), false);  for (byte i = 0; i < 8; i++) lcdSend(rows[i], true);  lcdSend(0x80, false);  // back to writing letters}// ---------- Commands from the computer ----------void readComputer() {  static char line[20];  static byte length = 0;  while (Serial.available()) {    char ch = Serial.read();    if (ch == '\n' || ch == '\r') {      line[length] = '\0';      if (length > 0) handleCommand(line);      length = 0;    } else if (length < sizeof(line) - 1) {      line[length++] = ch;    }  }}void handleCommand(const char *line) {  int value = constrain(atoi(line + 1), 0, 255);  switch (line[0]) {    case 't':    case 'p':      stopAllSound();      settings.mode = (line[0] == 'p') ? MODE_PIANO : MODE_THEREMIN;      playStartSound();      showIdle();      break;    case 'm':      settings.muted = !settings.muted;      stopAllSound();      showIdle();      break;    case 'c':      settings.contrast = value;      analogWrite(LCD_CONTRAST, settings.contrast);      break;    case 'b':      settings.backlight = value;      analogWrite(LCD_LIGHT, settings.backlight);      break;    case '?':      reportStatus();      return;    case 'f':      stopAllSound();      for (byte i = 0; i < 3; i++) {        digitalWrite(BUZZER, HIGH);        delay(150);        digitalWrite(BUZZER, LOW);        delay(150);      }      Serial.println("Blinked");      return;    default:      return;  }  EEPROM.put(0, settings);  printMode();}// "?": is the sensor there, and what does it see right now? With a pull-up on,// a powered sensor holds its Echo pin LOW; with no sensor both pins read HIGH,// and with the wires in but no power both read LOW.void reportStatus() {  pinMode(SENSOR_PINS[0], INPUT_PULLUP);  pinMode(SENSOR_PINS[1], INPUT_PULLUP);  delay(2);  bool low0 = digitalRead(SENSOR_PINS[0]) == LOW;  bool low1 = digitalRead(SENSOR_PINS[1]) == LOW;  findSensorPins();  Serial.print("Sensor: ");  if (low0 != low1) {    Serial.print("found (Trig ");    Serial.print(trigPin);    Serial.print(", Echo ");    Serial.print(echoPin);    Serial.print(")");  } else if (low0 && low1) {    Serial.print("NOT found: pins 7 and 8 both LOW (no power? check 5V/GND)");  } else {    Serial.print("NOT found: pins 7 and 8 both HIGH (Trig/Echo wires not connected?)");  }  delay(60);  float inches = readInches();  Serial.print("   sees: ");  if (inches > 0) {    Serial.print(inches, 1);    Serial.print(" in");  } else {    Serial.print("nothing within 30 in");  }  Serial.print(settings.mode == MODE_PIANO ? "   mode: piano" : "   mode: theremin");  Serial.println(settings.muted ? "   sound: muted" : "   sound: on");}// ---------- Screen driver ----------// The screen takes letters 4 bits at a time on its D4-D7 pins. RS picks// between a command (LOW) and a letter (HIGH), and a pulse on E sends it.void lcdBegin() {  pinMode(LCD_RS, OUTPUT);  pinMode(LCD_E, OUTPUT);  for (byte i = 0; i < 4; i++) pinMode(LCD_DATA[i], OUTPUT);  digitalWrite(LCD_E, LOW);  digitalWrite(LCD_RS, LOW);  delay(50);  lcdWake();  lcdSend(0x01, false);  // clear the screen  delay(2);}// The screen's start-up routine. Repeating it before each update gets a// screen that had a glitch back in step, without clearing it.void lcdWake() {  digitalWrite(LCD_RS, LOW);  lcdNibble(0x3);  delay(5);  lcdNibble(0x3);  delayMicroseconds(150);  lcdNibble(0x3);  delayMicroseconds(150);  lcdNibble(0x2);  delayMicroseconds(150);  lcdSend(0x28, false);  // 2 lines of text  lcdSend(0x0C, false);  // screen on, no cursor  lcdSend(0x06, false);  // move right after each letter}void lcdNibble(byte bits) {  for (byte i = 0; i < 4; i++) digitalWrite(LCD_DATA[i], (bits >> i) & 1);  digitalWrite(LCD_E, HIGH);  delayMicroseconds(1);  digitalWrite(LCD_E, LOW);  delayMicroseconds(100);}void lcdSend(byte value, bool isLetter) {  digitalWrite(LCD_RS, isLetter ? HIGH : LOW);  lcdNibble(value >> 4);  lcdNibble(value & 0x0F);}// Writes a whole row: the text, then spaces to fill all 16 places.void lcdPrintRow(byte row, const char *text) {  lcdSend(0x80 | (row ? 0x40 : 0), false);  bool ended = false;  for (byte i = 0; i < 16; i++) {    if (text[i] == '\0') ended = true;    lcdSend(ended ? ' ' : text[i], true);  }}