#include <Wire.h>
#include <SPI.h>

#include <Adafruit_GFX.h>
#include <Adafruit_SSD1306.h>

#define SCREEN_WIDTH 128 // OLED display width, in pixels
#define SCREEN_HEIGHT 64 // OLED display height, in pixels
#define OLED_RESET     4 // Reset pin # (or -1 if sharing Arduino reset pin)
#define SCREEN_ADDRESS 0x3D ///< See datasheet for Address; 0x3D for 128x64, 0x3C for 128x32
Adafruit_SSD1306 display(SCREEN_WIDTH, SCREEN_HEIGHT, &Wire, OLED_RESET);
// create what ever variables you need
double volts;
double bvolts;
double x, y;

// these are a required variables for the graphing functions
bool Redraw1 = true;
bool Redraw2 = true;
bool Redraw3 = true;
bool Redraw4 = true;
double ox , oy ;

void setup() {

  Serial.begin(9600);

  // initialize the display
  // note you may have to change the address
  // the most common are 0X3C and 0X3D

  display.begin(SSD1306_SWITCHCAPVCC, 0x3c);
  // if you distribute your code, the adafruit license requires you show their splash screen
  // otherwise clear the video buffer memory then display
  display.display();
  //delay(2000);
  display.clearDisplay();
  display.display();

  // establish whatever pin reads you need
  pinMode(A1, INPUT);

}

unsigned long OldTime;
unsigned long counter;


  void loop(void) {

  // read some values and convert to volts
  bvolts = analogRead(A1);
  volts = (bvolts  / 204.6 ) ;


  // draw any of the following, sorry for the crazy long arguement lists
  // note 0.96 isn't very big, so you can't show many graphs at the same time
  // also colors are hard coded
  // the display i use draws text at the top in yellow--we'll use that for drawing the title


  // call one of these functions
  // DrawBarChartV(display, bvolts, 25,  60, 40, 40, 0, 1024 , 256, 0, "A0 (bits)", Redraw1);
  //  DrawBarChartH(display, volts, 10, 45, 100, 20, 0, 5, 1, 0, "A1 (volts)", Redraw2);
  //  DrawDial(display, volts, 65, 50, 25, 0, 5 , 1, 0, 200, "A0 (volts)", Redraw3);

  // for multiple graphs uncomment the next 2 lines
  //  DrawBarChartV(display, bvolts, 5,  60, 10, 40, 0, 1024 , 256, 0, "A1 (bits/volts)", Redraw1);
  //  DrawDial(display, volts, 90, 50, 25, 0, 5 , 1, 0, 200, "A0 (bits/volts)", Redraw3);

  // or show a cartesian style graph to plot values over time (or whatever)

    DrawCGraph(display, x++, bvolts, 30, 50, 75, 30, 0, 100, 25, 0, 1024, 512, 0, "milliVolts vs Seconds", Redraw4);
    if (x > 100) {
    while (1) {}
    }


  delay(100);


  }

void DrawCGraph(Adafruit_SSD1306 &d, double x, double y, double gx, double gy, double w, double h, double xlo, double xhi, double xinc, double ylo, double yhi, double yinc, double dig, String title, boolean &Redraw) {

  double i;
  double temp;
  int rot, newrot;

  if (Redraw == true) {
    Redraw = false;
    d.fillRect(0, 0,  127 , 16, SSD1306_WHITE);
    d.setTextColor(SSD1306_BLACK, SSD1306_WHITE);
    d.setTextSize(1);
    d.setCursor(2, 4);
    d.println(title);
    ox = (x - xlo) * ( w) / (xhi - xlo) + gx;
    oy = (y - ylo) * (gy - h - gy) / (yhi - ylo) + gy;
    // draw y scale
    d.setTextSize(1);
    d.setTextColor(SSD1306_WHITE, SSD1306_BLACK);
    for ( i = ylo; i <= yhi; i += yinc) {
      // compute the transform
      // note my transform funcition is the same as the map function, except the map uses long and we need doubles
      temp =  (i - ylo) * (gy - h - gy) / (yhi - ylo) + gy;
      if (i == 0) {
        d.drawFastHLine(gx - 3, temp, w + 3, SSD1306_WHITE);
      }
      else {
        d.drawFastHLine(gx - 3, temp, 3, SSD1306_WHITE);
      }
      d.setCursor(gx - 27, temp - 3);
      d.println(i, dig);
    }
    // draw x scale
    for (i = xlo; i <= xhi; i += xinc) {
      // compute the transform
      d.setTextSize(1);
      d.setTextColor(SSD1306_WHITE, SSD1306_BLACK);
      temp =  (i - xlo) * ( w) / (xhi - xlo) + gx;
      if (i == 0) {
        d.drawFastVLine(temp, gy - h, h + 3, SSD1306_WHITE);
      }
      else {
        d.drawFastVLine(temp, gy, 3, SSD1306_WHITE);
      }
      d.setCursor(temp, gy + 6);
      d.println(i, dig);
    }
  }

  // graph drawn now plot the data
  // the entire plotting code are these few lines...

  x =  (x - xlo) * ( w) / (xhi - xlo) + gx;
  y =  (y - ylo) * (gy - h - gy) / (yhi - ylo) + gy;
  d.drawLine(ox, oy, x, y, SSD1306_WHITE);
  d.drawLine(ox, oy - 1, x, y - 1, SSD1306_WHITE);
  ox = x;
  oy = y;
  
  // up until now print sends data to a video buffer NOT the screen
  // this call sends the data to the screen
  d.display();

}


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