#include <Adafruit_GFX.h>
#include <Adafruit_PCD8544.h> // https://github.com/adafruit/Adafruit-PCD8544-Nokia-5110-LCD-library/blob/master/

// Hardware SPI
// SCK 13
// DIN 11
Adafruit_PCD8544 display = Adafruit_PCD8544(5, 7, 6); // DC, CS, RST

// https://www.espboards.dev/tools/monochrome-bitmap-tool // monochrome 16x16 bitmap editor
static const unsigned char PROGMEM heart[] =
{ B00111100, B00111100,
  B01000010, B01000010,
  B10000001, B10000001,
  B10000000, B00000001,
  B10000000, B00000001,
  B10000000, B00000001,
  B10000000, B00000001,
  B01000000, B00000010,
  B01000000, B00000010,
  B00100000, B00000100,
  B00100000, B00000100,
  B00010000, B00001000,
  B00001000, B00010000,
  B00000100, B00100000,
  B00000010, B01000000,
  B00000001, B10000000,
};

int x, y, oldX[60], oldY[60], start = 25, center = 33; // trace arrays

void setup()   {
  Serial.begin(9600); // start serial comms
  display.begin(); // start display instance
  display.clearDisplay();   // clears display buffer
  display.display(); // show buffer
  display.setTextSize(2);
  oldX[0] = start; // place the first pixel
  oldY[0] = center; // place the first pixel

  Serial.print("(");
  Serial.print(oldX[0]);
  Serial.print(",");
  Serial.print(oldY[0]);
  Serial.println(")");
}

void loop() {
  int offset = map(analogRead(A0), 0, 1023, -8, 8); // range
  display.clearDisplay();
  display.setCursor(5, 5);
  display.print("PPM: ");
  display.setCursor(50, 5);
  if (offset >= 0)
    display.print(" ");
  display.print(offset);
  display.drawBitmap(5, 25, heart, 16, 16, 1); // x, y, bitmap, sizeX, sizeY, color

  if (x == 60) // new x
    x = 0;
  y = center + offset; // new y
  // for (int i = 0; i < x; i++) { // count from start of trace to current x
  // display.drawLine(oldX[x], oldY[x], x, y, BLACK);
  Serial.print(x);
  Serial.print(" (");
  Serial.print(oldX[x]);
  Serial.print(",");
  Serial.print(oldY[x]);
  Serial.print(")(");
  Serial.print(x);
  Serial.print(",");
  Serial.print(y);
  Serial.println(")");
  oldX[x] = x; // store last value
  oldY[x] = y;
  // }
  display.display(); // display the new trace
  x++; // next x
  delay(50);
}