airhockey.ino

/*
 * Air Hockey Score Board
 * 
 * This project added electronic score keeping to a little tabletop air hockey game
 * 
 * I made light blocking sensors for the goals using pairs of infrared LEDs, one 
 * emitting light, the other acting as a sensor, amplified through an NPN transistor
 * 
 * The scoreboard itself contains a small speaker, a 4 digit LED display and a push
 * button attached to the arduino's reset pin. The display is a TM1637 which is an
 * i2c device. We use a library that makes it easy so we can just print strings to it.
 * 
 */

#include <TM1637.h>

// 4 digit LED display
TM1637 tm(A5, A4);

// I heard somewhere, in the official rules of air hockey, the winner is the
// first to reach 7 points..
int max_points = 9;

// copypasta from arduino smoothing example
const int numReadings = 100;  // tune this for smoothing vs responsiveness
int readIndex = 0;
int g0_readings[numReadings];
int g0_total = 0;
int g0_average = 0;
int g0_inputPin = A2;         // Goal 0 sensor pin
int g1_readings[numReadings];
int g1_total = 0;
int g1_average = 0;
int g1_inputPin = A3;         // Goal 1 sensor pin

unsigned int counter = 0;     // just an arbitrary int to count how many times we've been through the loop and we don't care if we overflow it

bool g0_puck = false;         // puck in goal?
bool g1_puck = false;

bool g0_last_puck = false;    // puck state last time through the loop
bool g1_last_puck = false;

int g0_score = 0;
int g1_score = 0;

bool warmed_up = false;

void setup() {
  Serial.begin(115200);

  tm.init();
  //  tm.setBrightness(0);

  // initialize all the readings to 0:
  for (int thisReading = 0; thisReading < numReadings; thisReading++) {
    g0_readings[thisReading] = 0;
    g1_readings[thisReading] = 0;
  }

  // beep
  tone(9, 262, 500);

  // display the score
  tm.display(String(String(g0_score) + "  " + String(g1_score)));
}

void loop() {

  // avoid jankyness on boot, might not still be needed
  if (counter > 1000) {
    warmed_up = true;
  }

  // read the voltage from the goal 0 sensor, 0-5V is represented as 0-1023
  g0_total = g0_total - g0_readings[readIndex];
  g0_readings[readIndex] = analogRead(g0_inputPin);
  g0_total = g0_total + g0_readings[readIndex];

  // sleep for 1ms between readings for stability
  delay(1);

  // read the goal 1 sensor
  g1_total = g1_total - g1_readings[readIndex];
  g1_readings[readIndex] = analogRead(g1_inputPin);
  g1_total = g1_total + g1_readings[readIndex];

  // calculate averages
  g0_average = g0_total / numReadings;
  g1_average = g1_total / numReadings;

  delay(1);

  readIndex = readIndex + 1;
  if (readIndex >= numReadings) {
    readIndex = 0;
  }

  // when the puck is in the goal, the average is something like -233, otherwise it is > 300 typically
  g0_puck = g0_average < 0;
  g1_puck = g1_average < 0;

  if (warmed_up) {
    if (g0_puck != g0_last_puck) {
      if (g0_puck == true) {
        g0_score++;
        tm.display(String(String(g0_score) + "  " + String(g1_score))); // display score
        tone(9, 523, 400); // beep
        delay(100); // debounce
      }
      if (g0_puck == false) {
        delay(4000); // allow 4 seconds to get the puck out
      }
    }

    if (g1_puck != g1_last_puck) {
      if (g1_puck == true) {
        g1_score++;
        tm.display(String(String(g0_score) + "  " + String(g1_score))); // display
        tone(9, 523, 400);
        delay(100); // debounce
      }
      if (g1_puck == false) {
        delay(4000); // allow 3 seconds to get the puck out
      }
    }
  }

  //  Serial.print(g0_val);
  //  Serial.print("\t");
  //  Serial.println(g1_val);

  //  Serial.println(scoreString);

  // Game over, max points reached
  if ((g0_score == max_points) || (g1_score == max_points)) {
    // beep 3 times
    delay(900);
    tone(9, 523, 500);
    delay(1000);
    tone(9, 523, 500);
    delay(1000);
    tone(9, 523, 500);
    while (true) {
      // flash the score forever, or until someone hits the reset button
      tm.display("    ");
      delay(1000);
      tm.display(String(String(g0_score) + "  " + String(g1_score)));
      delay(1000);
    }
  }

  counter++;

  g0_last_puck = g0_puck;
  g1_last_puck = g1_puck;

}