Display analog input in a time/value graph on a OLED screen.

esp8266_analog_graph_oled.ino

#include <SPI.h> 
#include "SSD1306Spi.h"

// The OLED display width and height
#define int DISPLAY_HEIGHT = 64;
#define int DISPLAY_WIDTH = 128;

SSD1306Spi display(0,16,2); // RESET, DC, CS

byte count;
byte sensorArray[128];
byte drawHeight;

void setup() {
  // Init and flip the OLED display
  display.init();
  display.flipScreenVertically();
  // Set contrast and font
  display.setContrast(255);
  display.setFont(ArialMT_Plain_10);

  // Display some info on the OLED
  display.clear();

  for (count = 0; count <= DISPLAY_WIDTH; count++) //zero all elements
  {
    sensorArray[count] = 0;
  }
}

// handle websocket requests forever.
void loop() {
  drawHeight = map(analogRead(17), 0, 1023, 0, DISPLAY_HEIGHT );
  sensorArray[0] = drawHeight;
  for (count = 1; count <= DISPLAY_WIDTH; count++ ){
    display.drawLine(count, DISPLAY_HEIGHT, count, DISPLAY_HEIGHT - sensorArray[count - 1]);
  }
  drawAxises();
  display.display();  //needed before anything is displayed
  display.clear(); //clear before new drawing
  for (count = DISPLAY_WIDTH; count >= 2; count--) // count down from 160 to 2
    {
      sensorArray[count - 1] = sensorArray[count - 2];
    }


}

void drawAxises(){
  display.drawLine(0,0,0,DISPLAY_HEIGHT);
  display.drawLine(DISPLAY_WIDTH-1,0,DISPLAY_WIDTH-1,DISPLAY_HEIGHT);
  for (count = 0; count < 64; count += 10)
  {
    display.drawLine(DISPLAY_WIDTH, count, DISPLAY_WIDTH-5, count);
    display.drawLine(0, count, 5, count);
  }

  for (count = 10; count < DISPLAY_WIDTH; count += 10)
  {
    display.setPixel(count, 0);
    display.setPixel(count, DISPLAY_HEIGHT);
  }
}