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

#define SCREEN_WIDTH 128 // OLED width,  in pixels
#define SCREEN_HEIGHT 64 // OLED height, in pixels

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

int so2 = 35;
int lk = 0;
int lg = 15;
int lr = 2;
int Do2;
float o2 = 0.00;

void setup() {
  Serial.begin(9600);
  pinMode(lr, OUTPUT);
  pinMode(lg, OUTPUT);
  pinMode(lk, OUTPUT);
  if (!oled.begin(SSD1306_SWITCHCAPVCC, 0x3C)) {
    Serial.println(F("failed to start SSD1306 OLED"));
    while (1);
  }

  delay(200);         // wait two seconds for initializing
  oled.clearDisplay(); // clear display

  oled.setTextSize(1);         // set text size
  oled.setTextColor(WHITE);    // set text color
  oled.setCursor(4,7);       // set position to display (x,y)
  oled.println("WELCOM"); // set text
  oled.display();              // display on OLED
  delay(1000);
  oled.clearDisplay();
}

void loop() {
  Do2 = analogRead(so2);
  o2 = (Do2 * 1.40) / 4095;
  Serial.print("S.OKs=");
  Serial.print(Do2);
  Serial.print(" ");
  Serial.print(o2);
  Serial.println("v ");
  delay(200);
  

if (o2 >= 0.70) 
{
  digitalWrite(lr, HIGH);
  digitalWrite(lg, LOW);
}
else if (o2 > 0.30 && o2 < 0.70)
{
  digitalWrite(lr, LOW);
  digitalWrite(lg, HIGH);
}

else if (o2 > 0 && o2 <0.30)
{
  digitalWrite(lg, HIGH);
  digitalWrite(lr, HIGH);
}
else                      
{
  digitalWrite(lr, LOW);
  digitalWrite(lg, LOW);
}
}