#include <Wire.h>
#include <Adafruit_GFX.h>
#include <Adafruit_SSD1306.h>
#include <Fonts/FreeSerif9pt7b.h>

#define SCREEN_WIDTH 128
#define SCREEN_HEIGHT 64

Adafruit_SSD1306 display(SCREEN_WIDTH, SCREEN_HEIGHT, &Wire, -1);

const int potPIN = A0;
int value = 0;
int graphValue = 0;
int prevGraphValue = 64;
int timeAxis = 0;
int timeAxisStep = 5;

void setup() {
  Serial.begin(115200);

  if(!display.begin(SSD1306_SWITCHCAPVCC, 0x3C)) { 
    Serial.println("SSD1306 allocation failed");
    for(;;);
  }
  delay(1000);

  display.setFont(&FreeSerif9pt7b);
  display.clearDisplay();
  display.setTextSize(1);             
  display.setTextColor(WHITE);        
  display.setCursor(0,20);             
  display.println("Kovalchuk IC-22");
  display.display();
  delay(3000); 
  display.clearDisplay();
}
void loop() 
{
  if(timeAxis + 10 >= 128)
  {
    display.clearDisplay();
    timeAxis = 0;
  }

  value = analogRead(potPIN);
  graphValue = 64 - value/16;

  display.drawLine(timeAxis, prevGraphValue, timeAxis + timeAxisStep, graphValue, WHITE);
  display.display();

  timeAxis += timeAxisStep;
  prevGraphValue = graphValue;

  delay(500);
}