Display waveform on mini OLED with Arduino Nano

Display oscilloscope-like waveform on 0.96" 128X64 I2C OLED with Arduino Nano. Read analog input (A0) and plot the waveform acordingly.

// ref u8glib: https://code.google.com/p/u8glib/
// To install u8glib on Arduino IDE: http://goo.gl/j3olBA
#include "U8glib.h"

U8GLIB_SSD1306_128X64 u8g(U8G_I2C_OPT_NONE|U8G_I2C_OPT_DEV_0);

const int WIDTH=128;
const int HEIGHT=64;
const int LENGTH=WIDTH;

const int analogInPin = A0;
int analogInValue = 0;

int x;
int y[LENGTH];

void clearY(){
  for(int i=0; i<LENGTH; i++){
    y[i] = -1;
  }
}

void drawY(){
  u8g.drawPixel(0, y[0]);
  for(int i=1; i<LENGTH; i++){
    if(y[i]!=-1){
      //u8g.drawPixel(i, y[i]);
      u8g.drawLine(i-1, y[i-1], i, y[i]);
    }else{
      break;
    }
  }
}

void setup(void) {
  x = 0;
  clearY();
}

void loop(void) {
  
  analogInValue = analogRead(analogInPin);
  
  y[x] = map(analogInValue, 0, 1023, HEIGHT-1, 0);;

  u8g.firstPage();  
  do {
    drawY();
  } while( u8g.nextPage() );
  
  //delay(10);

  x++;
  if(x >= WIDTH){
    x = 0;
    clearY();
  }
}

This example read analog input inside loop(), it's not in fixed timing, and affected by the slow operation of displaying. To read input in accurate timing, Refer to next post "Capture analog input in Timer Interrupt".