Reaction Game

// Reaction game
// Wait until the LED turns on and then press the button as fast as you can.
// The screen shows how fast you were!

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

const int BUTTON_PIN = 2;   // Pushbutton on pin 2 (other side to GND)
const int LED_PIN = 13;   // LED on pin 13 (through the resistor)

Adafruit_SSD1306 display(128, 32, &Wire, -1);  // OLED: SDA = A4, SCL = A5

unsigned long bestTime = 0;   // Your fastest time so far

// Put text big on the screen
void show(const __FlashStringHelper* top, unsigned long number) {
  display.clearDisplay();
  display.setTextSize(1);
  display.setCursor(0, 0);
  display.print(top);
  if (number > 0) {
    display.setTextSize(2);
    display.setCursor(0, 14);
    display.print(number);
    display.print(F(" ms"));
  }
  display.display();
}

void setup() {
  pinMode(BUTTON_PIN, INPUT_PULLUP);
  pinMode(LED_PIN, OUTPUT);
  randomSeed(analogRead(A0));    // Makes really random wait times
  display.begin(SSD1306_SWITCHCAPVCC, 0x3C);
  display.setTextColor(SSD1306_WHITE);
}

void loop() {
  show(F("Press the button..."), 0);
  while (digitalRead(BUTTON_PIN) == HIGH);   // Wait until you press the button
  while (digitalRead(BUTTON_PIN) == LOW);    // ...and let go again
  show(F("Ready? Watch LED!"), 0);

  delay(random(2000, 5000));               // A secret wait time between 2 and 5 seconds

  if (digitalRead(BUTTON_PIN) == LOW) {      // Pressed too soon? Cheater!
    show(F("Too soon! Again."), 0);
    delay(2000);
    return;
  }

  digitalWrite(LED_PIN, HIGH);             // NOW!
  unsigned long start = millis();
  while (digitalRead(BUTTON_PIN) == HIGH);   // Wait for your press
  unsigned long time = millis() - start;
  digitalWrite(LED_PIN, LOW);

  if (bestTime == 0 || time < bestTime) {
    bestTime = time;
    show(F("NEW RECORD!"), time);
  } else {
    show(F("Your time:"), time);
  }
  delay(3000);
}