/*
#include <Wire.h>
#include <Adafruit_GFX.h>
#include <Adafruit_SSD1306.h>
#include <math.h>

#define SCREEN_WIDTH 128
#define SCREEN_HEIGHT 64
#define OLED_RESET -1
#define OLED_ADDR 0x3C

Adafruit_SSD1306 display(SCREEN_WIDTH, SCREEN_HEIGHT, &Wire, OLED_RESET);

#define BUTTON_WAVE1 PB0
#define BUTTON_WAVE2 PB1

#define SAMPLE_COUNT 256

uint16_t wave1[SAMPLE_COUNT];
uint16_t wave2[SAMPLE_COUNT];

bool showWave1 = false;
bool showWave2 = false;

bool wave1Selected = false;
bool wave2Selected = false;

void createSineWave(uint16_t *wave)
{
  for (int i = 0; i < SAMPLE_COUNT; i++)
  {
    float angle = 2.0 * PI * (float)i / (float)SAMPLE_COUNT;

    float voltage = 1.5 + 1.5 * sin(angle);

    if (voltage < 0.0)
    {
      voltage = 0.0;
    }

    if (voltage > 3.0)
    {
      voltage = 3.0;
    }

    wave[i] = (uint16_t)((voltage / 3.0) * 4095.0);
  }
}

void drawLabel(const char *text, int x, int y, bool selected)
{
  int width = 38;
  int height = 9;

  if (selected)
  {
    display.fillRect(x, y, width, height, SSD1306_WHITE);
    display.setTextColor(SSD1306_BLACK);
  }
  else
  {
    display.fillRect(x, y, width, height, SSD1306_BLACK);
    display.setTextColor(SSD1306_WHITE);
  }

  display.setTextSize(1);
  display.setCursor(x + 2, y + 1);
  display.print(text);

  display.setTextColor(SSD1306_WHITE);
}

void drawTrace(uint16_t *wave, int top, int bottom)
{
  int height = bottom - top;
  int previousY = -1;

  for (int x = 0; x < 128; x++)
  {
    int index1 = x * 2;
    int index2 = index1 + 1;

    if (index2 >= SAMPLE_COUNT)
    {
      index2 = SAMPLE_COUNT - 1;
    }

    uint32_t average =
      ((uint32_t)wave[index1] + (uint32_t)wave[index2]) / 2;

    int y =
      bottom - ((average * height) / 4095);

    if (y < top)
    {
      y = top;
    }

    if (y > bottom)
    {
      y = bottom;
    }

    if (previousY >= 0)
    {
      display.drawLine(
        x - 1,
        previousY,
        x,
        y,
        SSD1306_WHITE
      );
    }

    previousY = y;
  }
}

void updateDisplay()
{
  display.clearDisplay();

  drawLabel("WAVE 1", 0, 0, wave1Selected);
  drawLabel("WAVE 2", 0, 32, wave2Selected);

  if (showWave1)
  {
    drawTrace(wave1, 10, 30);
  }

  if (showWave2)
  {
    drawTrace(wave2, 42, 63);
  }

  display.display();
}

void setup()
{
  pinMode(BUTTON_WAVE1, INPUT_PULLUP);
  pinMode(BUTTON_WAVE2, INPUT_PULLUP);

  Wire.setSDA(PB7);
  Wire.setSCL(PB6);
  Wire.begin();
  Wire.setClock(100000);

  if (!display.begin(SSD1306_SWITCHCAPVCC, OLED_ADDR))
  {
    while (1)
    {
    }
  }

  createSineWave(wave1);

  for (int i = 0; i < SAMPLE_COUNT; i++)
  {
    wave2[i] = wave1[i];
  }

  showWave1 = false;
  showWave2 = false;

  wave1Selected = false;
  wave2Selected = false;

  updateDisplay();
}

void loop()
{
  if (digitalRead(BUTTON_WAVE1) == LOW)
  {
    showWave1 = true;
    showWave2 = false;

    wave1Selected = true;
    wave2Selected = false;

    updateDisplay();

    delay(250);
  }

  if (digitalRead(BUTTON_WAVE2) == LOW)
  {
    showWave1 = true;
    showWave2 = true;

    wave1Selected = false;
    wave2Selected = true;

    updateDisplay();

    delay(250);
  }
}
*/

/*
#include <Wire.h>
#include <Adafruit_GFX.h>
#include <Adafruit_SSD1306.h>
#include <math.h>

#define SCREEN_WIDTH 128
#define SCREEN_HEIGHT 64
#define OLED_RESET -1
#define OLED_ADDR 0x3C

Adafruit_SSD1306 display(SCREEN_WIDTH, SCREEN_HEIGHT, &Wire, OLED_RESET);

#define BUTTON_WAVE1 PB0
#define BUTTON_WAVE2 PB1
#define BUTTON_WAVE2B PB3
#define BUTTON_COMPARE PB4

#define SAMPLE_COUNT 256

uint16_t wave1[SAMPLE_COUNT];
uint16_t wave2[SAMPLE_COUNT];

bool showWave1 = false;
bool showWave2 = false;

bool wave1Selected = false;
bool wave2Selected = false;

bool wave2Available = false;

float comparisonPercent = 0.0;


// Create stored sine wave
void createSineWave(uint16_t *wave, float amplitude)
{
  for (int i = 0; i < SAMPLE_COUNT; i++)
  {
    float angle =
      2.0 * PI * (float)i / (float)SAMPLE_COUNT;

    float voltage =
      1.5 + (1.5 * amplitude * sin(angle));

    if (voltage < 0.0)
      voltage = 0.0;

    if (voltage > 3.0)
      voltage = 3.0;

    wave[i] =
      (uint16_t)((voltage / 3.0) * 4095.0);
  }
}


// Draw WAVE 1 / WAVE 2 label
void drawLabel(
  const char *text,
  int x,
  int y,
  bool selected
)
{
  int width = 40;
  int height = 9;

  if (selected)
  {
    display.fillRect(
      x,
      y,
      width,
      height,
      SSD1306_WHITE
    );

    display.setTextColor(
      SSD1306_BLACK
    );
  }
  else
  {
    display.fillRect(
      x,
      y,
      width,
      height,
      SSD1306_BLACK
    );

    display.setTextColor(
      SSD1306_WHITE
    );
  }

  display.setTextSize(1);

  display.setCursor(
    x + 2,
    y + 1
  );

  display.print(text);

  display.setTextColor(
    SSD1306_WHITE
  );
}


// Draw waveform
void drawTrace(
  uint16_t *wave,
  int top,
  int bottom
)
{
  int height = bottom - top;

  int previousY = -1;

  for (int x = 0; x < 128; x++)
  {
    int index1 = x * 2;
    int index2 = index1 + 1;

    if (index2 >= SAMPLE_COUNT)
      index2 = SAMPLE_COUNT - 1;

    uint32_t average =
      ((uint32_t)wave[index1] +
       (uint32_t)wave[index2]) / 2;

    int y =
      bottom -
      ((average * height) / 4095);

    if (y < top)
      y = top;

    if (y > bottom)
      y = bottom;

    if (previousY >= 0)
    {
      display.drawLine(
        x - 1,
        previousY,
        x,
        y,
        SSD1306_WHITE
      );
    }

    previousY = y;
  }
}


// Display waveform screen
void updateWaveformDisplay()
{
  display.clearDisplay();

  drawLabel(
    "WAVE 1",
    0,
    0,
    wave1Selected
  );

  drawLabel(
    "WAVE 2",
    0,
    32,
    wave2Selected
  );

  if (showWave1)
  {
    drawTrace(
      wave1,
      10,
      30
    );
  }

  if (showWave2)
  {
    drawTrace(
      wave2,
      42,
      63
    );
  }

  display.display();
}


// Compare REF and current WAVE 2
float compareWaveforms()
{
  uint64_t totalDifference = 0;
  uint64_t totalReference = 0;

  for (int i = 0; i < SAMPLE_COUNT; i++)
  {
    int difference =
      abs(
        (int)wave1[i] -
        (int)wave2[i]
      );

    totalDifference += difference;

    totalReference += wave1[i];
  }

  if (totalReference == 0)
    return 0.0;

  float result =
    ((float)totalDifference /
     (float)totalReference) * 100.0;

  return result;
}


// Show full-screen comparison result
void showComparisonResult()
{
  comparisonPercent =
    compareWaveforms();

  display.clearDisplay();

  display.setTextColor(
    SSD1306_WHITE
  );

  display.setTextSize(1);

  display.setCursor(25, 0);
  display.print("WAVE COMPARISON");

  display.setCursor(0, 16);
  display.print("REF   : 100.0 %");

  display.setCursor(0, 28);
  display.print("INPUT : ");

  display.print(
    100.0 - comparisonPercent,
    1
  );

  display.print(" %");

  display.setCursor(0, 40);
  display.print("DIFF  : ");

  display.print(
    comparisonPercent,
    1
  );

  display.print(" %");

  display.setCursor(0, 53);

  if (comparisonPercent < 0.1)
  {
    display.print("RESULT: IDENTICAL");
  }
  else
  {
    display.print("RESULT: DIFFERENT");
  }

  display.display();
}


void setup()
{
  pinMode(
    BUTTON_WAVE1,
    INPUT_PULLUP
  );

  pinMode(
    BUTTON_WAVE2,
    INPUT_PULLUP
  );

  pinMode(
    BUTTON_WAVE2B,
    INPUT_PULLUP
  );

  pinMode(
    BUTTON_COMPARE,
    INPUT_PULLUP
  );

  Wire.setSDA(PB7);
  Wire.setSCL(PB6);

  Wire.begin();

  Wire.setClock(100000);

  if (!display.begin(
        SSD1306_SWITCHCAPVCC,
        OLED_ADDR))
  {
    while (1)
    {
    }
  }


  // Create REF Wave 1
  createSineWave(
    wave1,
    1.0
  );


  // Wave 2 initially contains identical waveform
  createSineWave(
    wave2,
    1.0
  );


  showWave1 = false;
  showWave2 = false;

  wave1Selected = false;
  wave2Selected = false;

  wave2Available = false;

  display.clearDisplay();
  display.display();
}


void loop()
{
  // PB1 / PB0
  // Show REF Wave 1
  // Clear Wave 2
  if (digitalRead(BUTTON_WAVE1) == LOW)
  {
    showWave1 = true;
    showWave2 = false;

    wave1Selected = true;
    wave2Selected = false;

    wave2Available = false;

    updateWaveformDisplay();

    delay(250);
  }


  // PB2 / PB1
  // Generate Wave 2A
  // Identical to REF
  if (digitalRead(BUTTON_WAVE2) == LOW)
  {
    createSineWave(
      wave2,
      1.0
    );

    showWave1 = true;
    showWave2 = true;

    wave1Selected = false;
    wave2Selected = true;

    wave2Available = true;

    updateWaveformDisplay();

    delay(250);
  }


  // PB3
  // Generate Wave 2B
  // 10% lower amplitude
  // Overwrite Wave 2A
  if (digitalRead(BUTTON_WAVE2B) == LOW)
  {
    createSineWave(
      wave2,
      0.9
    );

    showWave1 = true;
    showWave2 = true;

    wave1Selected = false;
    wave2Selected = true;

    wave2Available = true;

    updateWaveformDisplay();

    delay(250);
  }


  // PB4
  // Compare REF against current Wave 2
  if (digitalRead(BUTTON_COMPARE) == LOW)
  {
    if (wave2Available)
    {
      showComparisonResult();
    }

    delay(250);
  }
}
*/

/*
// Sine wave
#include <Wire.h>
#include <Adafruit_GFX.h>
#include <Adafruit_SSD1306.h>
#include <math.h>

#define SCREEN_WIDTH 128
#define SCREEN_HEIGHT 64
#define OLED_RESET -1
#define OLED_ADDR 0x3C

Adafruit_SSD1306 display(SCREEN_WIDTH, SCREEN_HEIGHT, &Wire, OLED_RESET);

#define BUTTON_WAVE1 PB0
#define BUTTON_WAVE2 PB1
#define BUTTON_WAVE2B PB3
#define BUTTON_COMPARE PB4

#define SAMPLE_COUNT 256

uint16_t wave1[SAMPLE_COUNT];
uint16_t wave2[SAMPLE_COUNT];

bool showWave1 = false;
bool showWave2 = false;

bool wave1Selected = false;
bool wave2Selected = false;

bool wave2Available = false;

int wave2Type = 0;

float comparisonPercent = 0.0;

void createSineWave(uint16_t *wave, float amplitude)
{
  for (int i = 0; i < SAMPLE_COUNT; i++)
  {
    float angle =
      2.0 * PI * (float)i / (float)SAMPLE_COUNT;

    float voltage =
      1.5 + (1.5 * amplitude * sin(angle));

    if (voltage < 0.0)
      voltage = 0.0;

    if (voltage > 3.0)
      voltage = 3.0;

    wave[i] =
      (uint16_t)((voltage / 3.0) * 4095.0);
  }
}

void drawLabel(
  const char *text,
  int x,
  int y,
  bool selected
)
{
  int width = 48;
  int height = 9;

  if (selected)
  {
    display.fillRect(
      x,
      y,
      width,
      height,
      SSD1306_WHITE
    );

    display.setTextColor(
      SSD1306_BLACK
    );
  }
  else
  {
    display.fillRect(
      x,
      y,
      width,
      height,
      SSD1306_BLACK
    );

    display.setTextColor(
      SSD1306_WHITE
    );
  }

  display.setTextSize(1);
  display.setCursor(x + 2, y + 1);
  display.print(text);

  display.setTextColor(SSD1306_WHITE);
}

void drawTrace(
  uint16_t *wave,
  int top,
  int bottom
)
{
  int height = bottom - top;
  int previousY = -1;

  for (int x = 0; x < 128; x++)
  {
    int index1 = x * 2;
    int index2 = index1 + 1;

    if (index2 >= SAMPLE_COUNT)
      index2 = SAMPLE_COUNT - 1;

    uint32_t average =
      ((uint32_t)wave[index1] +
       (uint32_t)wave[index2]) / 2;

    int y =
      bottom -
      ((average * height) / 4095);

    if (y < top)
      y = top;

    if (y > bottom)
      y = bottom;

    if (previousY >= 0)
    {
      display.drawLine(
        x - 1,
        previousY,
        x,
        y,
        SSD1306_WHITE
      );
    }

    previousY = y;
  }
}

void updateWaveformDisplay()
{
  display.clearDisplay();

  drawLabel(
    "WAVE 1",
    0,
    0,
    wave1Selected
  );

  if (wave2Type == 1)
  {
    drawLabel(
      "WAVE 2A",
      0,
      32,
      wave2Selected
    );
  }
  else if (wave2Type == 2)
  {
    drawLabel(
      "WAVE 2B",
      0,
      32,
      wave2Selected
    );
  }
  else
  {
    drawLabel(
      "WAVE 2",
      0,
      32,
      wave2Selected
    );
  }

  if (showWave1)
  {
    drawTrace(
      wave1,
      10,
      30
    );
  }

  if (showWave2)
  {
    drawTrace(
      wave2,
      42,
      63
    );
  }

  display.display();
}



float compareWaveforms()
{
  uint16_t refMin = 4095;
  uint16_t refMax = 0;

  uint16_t inputMin = 4095;
  uint16_t inputMax = 0;

  for (int i = 0; i < SAMPLE_COUNT; i++)
  {
    if (wave1[i] < refMin)
      refMin = wave1[i];

    if (wave1[i] > refMax)
      refMax = wave1[i];

    if (wave2[i] < inputMin)
      inputMin = wave2[i];

    if (wave2[i] > inputMax)
      inputMax = wave2[i];
  }

  float refAmplitude =
    (float)(refMax - refMin);

  float inputAmplitude =
    (float)(inputMax - inputMin);

  if (refAmplitude <= 0.0)
    return 0.0;

  float difference =
    ((refAmplitude - inputAmplitude) /
     refAmplitude) * 100.0;

  if (difference < 0.0)
    difference = -difference;

  return difference;
}

void showComparisonResult()
{
  comparisonPercent =
    compareWaveforms();

  display.clearDisplay();

  display.setTextColor(SSD1306_WHITE);
  display.setTextSize(1);

  display.setCursor(25, 0);
  display.print("WAVE COMPARISON");

  display.setCursor(0, 14);
  display.print("REF   : 100.0 %");

  display.setCursor(0, 25);
  display.print("INPUT : ");

  display.print(
    100.0 - comparisonPercent,
    1
  );

  display.print(" %");

  display.setCursor(0, 36);
  display.print("DIFF  : ");

  display.print(
    comparisonPercent,
    1
  );

  display.print(" %");

  display.setCursor(0, 48);

  if (wave2Type == 1)
  {
    display.print("WAVE 2A");
  }
  else if (wave2Type == 2)
  {
    display.print("WAVE 2B");
  }

  display.setCursor(0, 56);

  if (comparisonPercent < 0.1)
  {
    display.print("RESULT: IDENTICAL");
  }
  else
  {
    display.print("RESULT: DIFFERENT");
  }

  display.display();
}

void setup()
{
  pinMode(BUTTON_WAVE1, INPUT_PULLUP);
  pinMode(BUTTON_WAVE2, INPUT_PULLUP);
  pinMode(BUTTON_WAVE2B, INPUT_PULLUP);
  pinMode(BUTTON_COMPARE, INPUT_PULLUP);

  Wire.setSDA(PB7);
  Wire.setSCL(PB6);
  Wire.begin();
  Wire.setClock(100000);

  if (!display.begin(
        SSD1306_SWITCHCAPVCC,
        OLED_ADDR))
  {
    while (1)
    {
    }
  }

  createSineWave(
    wave1,
    1.0
  );

  createSineWave(
    wave2,
    1.0
  );

  showWave1 = false;
  showWave2 = false;

  wave1Selected = false;
  wave2Selected = false;

  wave2Available = false;

  wave2Type = 0;

  display.clearDisplay();
  display.display();
}

void loop()
{
  if (digitalRead(BUTTON_WAVE1) == LOW)
  {
    showWave1 = true;
    showWave2 = false;

    wave1Selected = true;
    wave2Selected = false;

    wave2Available = false;
    wave2Type = 0;

    updateWaveformDisplay();

    delay(250);
  }

  if (digitalRead(BUTTON_WAVE2) == LOW)
  {
    createSineWave(
      wave2,
      1.0
    );

    showWave1 = true;
    showWave2 = true;

    wave1Selected = false;
    wave2Selected = true;

    wave2Available = true;
    wave2Type = 1;

    updateWaveformDisplay();

    delay(250);
  }

  if (digitalRead(BUTTON_WAVE2B) == LOW)
  {
    createSineWave(
      wave2,
      0.9
    );

    showWave1 = true;
    showWave2 = true;

    wave1Selected = false;
    wave2Selected = true;

    wave2Available = true;
    wave2Type = 2;

    updateWaveformDisplay();

    delay(250);
  }

  if (digitalRead(BUTTON_COMPARE) == LOW)
  {
    if (wave2Available)
    {
      showComparisonResult();
    }

    delay(250);
  }
}
*/

// Ringing wave
#include <Wire.h>
#include <Adafruit_GFX.h>
#include <Adafruit_SSD1306.h>
#include <math.h>

#define SCREEN_WIDTH 128
#define SCREEN_HEIGHT 64
#define OLED_RESET -1
#define OLED_ADDR 0x3C

Adafruit_SSD1306 display(
  SCREEN_WIDTH,
  SCREEN_HEIGHT,
  &Wire,
  OLED_RESET
);

#define BUTTON_WAVE1 PB0
#define BUTTON_WAVE2 PB1
#define BUTTON_WAVE2B PB3
#define BUTTON_COMPARE PB4

#define SAMPLE_COUNT 256

uint16_t wave1[SAMPLE_COUNT];
uint16_t wave2[SAMPLE_COUNT];

bool showWave1 = false;
bool showWave2 = false;

bool wave1Selected = false;
bool wave2Selected = false;

bool wave2Available = false;

int wave2Type = 0;

float comparisonPercent = 0.0;

// Create a damped ringing waveform
void createRingingWave(
  uint16_t *wave,
  float damping
)
{
  for (int i = 0; i < SAMPLE_COUNT; i++)
  {
    float angle =
      2.0 * PI *
      8.0 *
      (float)i /
      (float)SAMPLE_COUNT;

    float envelope =
      exp(-damping * (float)i);

    float voltage =
      1.5 +
      (1.5 * envelope * sin(angle));

    if (voltage < 0.0)
      voltage = 0.0;

    if (voltage > 3.0)
      voltage = 3.0;

    wave[i] =
      (uint16_t)(
        (voltage / 3.0) * 4095.0
      );
  }
}

// Draw WAVE label
void drawLabel(
  const char *text,
  int x,
  int y,
  bool selected
)
{
  int width = 52;
  int height = 9;

  if (selected)
  {
    display.fillRect(
      x,
      y,
      width,
      height,
      SSD1306_WHITE
    );

    display.setTextColor(
      SSD1306_BLACK
    );
  }
  else
  {
    display.fillRect(
      x,
      y,
      width,
      height,
      SSD1306_BLACK
    );

    display.setTextColor(
      SSD1306_WHITE
    );
  }

  display.setTextSize(1);

  display.setCursor(
    x + 2,
    y + 1
  );

  display.print(text);

  display.setTextColor(
    SSD1306_WHITE
  );
}

// Draw waveform
void drawTrace(
  uint16_t *wave,
  int top,
  int bottom
)
{
  int height =
    bottom - top;

  int previousY = -1;

  for (int x = 0; x < 128; x++)
  {
    int index1 =
      x * 2;

    int index2 =
      index1 + 1;

    if (index2 >= SAMPLE_COUNT)
      index2 = SAMPLE_COUNT - 1;

    uint32_t average =
      (
        (uint32_t)wave[index1] +
        (uint32_t)wave[index2]
      ) / 2;

    int y =
      bottom -
      ((average * height) / 4095);

    if (y < top)
      y = top;

    if (y > bottom)
      y = bottom;

    if (previousY >= 0)
    {
      display.drawLine(
        x - 1,
        previousY,
        x,
        y,
        SSD1306_WHITE
      );
    }

    previousY = y;
  }
}

// Update waveform screen
void updateWaveformDisplay()
{
  display.clearDisplay();

  drawLabel(
    "WAVE 1",
    0,
    0,
    wave1Selected
  );

  if (wave2Type == 1)
  {
    drawLabel(
      "WAVE 2A",
      0,
      32,
      wave2Selected
    );
  }
  else if (wave2Type == 2)
  {
    drawLabel(
      "WAVE 2B",
      0,
      32,
      wave2Selected
    );
  }
  else
  {
    drawLabel(
      "WAVE 2",
      0,
      32,
      wave2Selected
    );
  }

  if (showWave1)
  {
    drawTrace(
      wave1,
      10,
      30
    );
  }

  if (showWave2)
  {
    drawTrace(
      wave2,
      42,
      63
    );
  }

  display.display();
}

// Compare ringing waveforms
float compareWaveforms()
{
  double totalDifference = 0.0;
  double totalReference = 0.0;

  for (int i = 0; i < SAMPLE_COUNT; i++)
  {
    float ref =
      (float)wave1[i] - 2048.0;

    float input =
      (float)wave2[i] - 2048.0;

    float difference =
      fabs(input - ref);

    totalDifference += difference;

    totalReference += fabs(ref);
  }

  if (totalReference <= 0.0)
    return 0.0;

  float result =
    (
      totalDifference /
      totalReference
    ) * 100.0;

  return result;
}

// Show full-screen comparison result
void showComparisonResult()
{
  comparisonPercent =
    compareWaveforms();

  display.clearDisplay();

  display.setTextColor(
    SSD1306_WHITE
  );

  display.setTextSize(1);

  display.setCursor(
    18,
    0
  );

  display.print(
    "RING COMPARISON"
  );

  display.setCursor(
    0,
    14
  );

  display.print(
    "REF   : 100.0 %"
  );

  display.setCursor(
    0,
    25
  );

  display.print(
    "INPUT : "
  );

  float inputPercent =
    100.0 - comparisonPercent;

  if (inputPercent < 0.0)
    inputPercent = 0.0;

  display.print(
    inputPercent,
    1
  );

  display.print(
    " %"
  );

  display.setCursor(
    0,
    36
  );

  display.print(
    "DIFF  : "
  );

  display.print(
    comparisonPercent,
    1
  );

  display.print(
    " %"
  );

  display.setCursor(
    0,
    47
  );

  if (wave2Type == 1)
  {
    display.print(
      "INPUT: WAVE 2A"
    );
  }
  else if (wave2Type == 2)
  {
    display.print(
      "INPUT: WAVE 2B"
    );
  }

  display.setCursor(
    0,
    57
  );

  if (comparisonPercent < 0.1)
  {
    display.print(
      "RESULT: IDENTICAL"
    );
  }
  else
  {
    display.print(
      "RESULT: DIFFERENT"
    );
  }

  display.display();
}

void setup()
{
  pinMode(
    BUTTON_WAVE1,
    INPUT_PULLUP
  );

  pinMode(
    BUTTON_WAVE2,
    INPUT_PULLUP
  );

  pinMode(
    BUTTON_WAVE2B,
    INPUT_PULLUP
  );

  pinMode(
    BUTTON_COMPARE,
    INPUT_PULLUP
  );

  Wire.setSDA(PB7);
  Wire.setSCL(PB6);

  Wire.begin();

  Wire.setClock(
    100000
  );

  if (!display.begin(
        SSD1306_SWITCHCAPVCC,
        OLED_ADDR))
  {
    while (1)
    {
    }
  }

  // Reference ringing waveform
  createRingingWave(
    wave1,
    0.010
  );

  // Initial identical waveform
  createRingingWave(
    wave2,
    0.010
  );

  showWave1 = false;
  showWave2 = false;

  wave1Selected = false;
  wave2Selected = false;

  wave2Available = false;

  wave2Type = 0;

  display.clearDisplay();

  display.display();
}

void loop()
{
  // PB1 - show reference waveform
  if (digitalRead(
        BUTTON_WAVE1) == LOW)
  {
    showWave1 = true;
    showWave2 = false;

    wave1Selected = true;
    wave2Selected = false;

    wave2Available = false;
    wave2Type = 0;

    updateWaveformDisplay();

    delay(250);
  }

  // PB2 - identical ringing waveform
  if (digitalRead(
        BUTTON_WAVE2) == LOW)
  {
    createRingingWave(
      wave2,
      0.010
    );

    showWave1 = true;
    showWave2 = true;

    wave1Selected = false;
    wave2Selected = true;

    wave2Available = true;
    wave2Type = 1;

    updateWaveformDisplay();

    delay(250);
  }

  // PB3 - faster damping
  if (digitalRead(
        BUTTON_WAVE2B) == LOW)
  {
    createRingingWave(
      wave2,
      0.015
    );

    showWave1 = true;
    showWave2 = true;

    wave1Selected = false;
    wave2Selected = true;

    wave2Available = true;
    wave2Type = 2;

    updateWaveformDisplay();

    delay(250);
  }

  // PB4 - compare
  if (digitalRead(
        BUTTON_COMPARE) == LOW)
  {
    if (wave2Available)
    {
      showComparisonResult();
    }

    delay(250);
  }
}