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

#define SCREEN_WIDTH 128 // OLED display width, in pixels
#define SCREEN_HEIGHT 60 // OLED display height, in pixels

#define OLED_RESET     -1 // Reset pin # (or -1 if sharing Arduino reset pin)
#define SCREEN_ADDRESS 0x3C
Adafruit_SSD1306 display(SCREEN_WIDTH, SCREEN_HEIGHT, &Wire, OLED_RESET);

double sum = 0;
int count = 0;
int rpm;

void setup() {
  // initialize with the I2C addr 0x3C
  if(!display.begin(SSD1306_SWITCHCAPVCC, 0x3C)) {
    Serial.println(F("SSD1306 allocation failed"));
    for(;;);
  }
  
  display.display();
  delay(2000); // Pause for 2 seconds

  Serial.begin(57600);
  FreqMeasure.begin();

  display.clearDisplay();
  display.setTextSize(2);      
  display.setTextColor(SSD1306_WHITE);  
  display.setCursor(0, 20);     
  display.print("RPM:  ");

  display.setTextSize(1);      
  display.setTextColor(SSD1306_WHITE);  
  display.setCursor(20, 0);     
  display.print("The Interceptors ");

  display.setTextSize(1);      
  display.setTextColor(SSD1306_WHITE);  
  display.setCursor(40, 53);     
  display.print("GTR600");

display.display();

}

void loop() {
  if (FreqMeasure.available()) {
    // average several readings together
    sum = sum + FreqMeasure.read();
    count = count + 1;
    if (count > 30) {
      float frequency = FreqMeasure.countToFrequency(sum / count);
      rpm = frequency * 60 / 9;
      delay(250);
      Serial.println(rpm);

      display.setTextSize(2);  
      display.setCursor(47,20);
      display.print(rpm);
      display.print("RPM"); 

      sum = 0;
      count = 0;
    }
  }
}