Laser tag: two Nanos

// Laser tag: one player on an Arduino Nano. Put two (or more) on the canvas,
// each with this sketch, pointed at each other.
//
//   trigger button   D4 and GND (INPUT_PULLUP: a press reads LOW)
//   IR LED           D3 -> 220 ohm -> IR LED -> GND (IrSender's pin)
//   VS1838B          OUT -> D2, VCC -> 5V, GND -> GND
//   hit LED          D5 -> 220 ohm -> red LED -> GND
//
// Pressing the trigger fires one shot: an NEC frame, address 0x1A and
// command 0x01, flashed at 38 kHz through the infrared LED. Whichever
// receiver the LED is pointed at decodes it. Your own receiver faces the
// same way as your LED, so you never tag yourself.
//
// Each hit lights the red LED for a moment and goes to the Serial Monitor.
// Five hits and you are tagged out: the LED stays on and the trigger stops
// working until the board is reset.
//
// # One shot per press
//
// A shot is the moment the button goes from HIGH to LOW, and then the gun
// reloads for half a second, so holding the button fires once and a bounce
// of the contacts never fires twice.
//
// # Why 38 kHz
//
// The receiver ignores light that is just on: sunlight and lamps are full of
// infrared. It only answers light flashing at 38 kHz, which IrSender makes
// by switching the LED on and off 38,000 times a second through every burst
// of the frame.

#define DECODE_NEC  // the only protocol a shot uses: the other decoders stay out of flash
#include <IRremote.hpp>

const uint8_t RECEIVE_PIN = 2;
const uint8_t LED_PIN = 3;
const uint8_t TRIGGER_PIN = 4;
const uint8_t HIT_PIN = 5;

const uint16_t TAG_ADDRESS = 0x1A;
const uint8_t SHOT = 0x01;
const unsigned long RELOAD_MS = 500;
const unsigned long HIT_MS = 300;
const uint8_t LIVES = 5;

uint8_t hits = 0;
unsigned long reloadedAt = 0;
unsigned long hitUntil = 0;
bool wasPressed = false;

void setup() {
  Serial.begin(115200);
  pinMode(TRIGGER_PIN, INPUT_PULLUP);
  pinMode(HIT_PIN, OUTPUT);
  IrReceiver.begin(RECEIVE_PIN);
  IrSender.begin(LED_PIN);
  Serial.println(F("Laser tag: press the button to fire"));
}

void loop() {
  unsigned long now = millis();

  bool pressed = digitalRead(TRIGGER_PIN) == LOW;
  if (pressed && !wasPressed && now >= reloadedAt && hits < LIVES) {
    reloadedAt = now + RELOAD_MS;
    IrSender.sendNEC(TAG_ADDRESS, SHOT, 0);
    Serial.println(F("Fire!"));
  }
  wasPressed = pressed;

  if (IrReceiver.decode()) {
    IRData &shot = IrReceiver.decodedIRData;
    bool repeat = shot.flags & IRDATA_FLAGS_IS_REPEAT;
    if (shot.protocol == NEC && shot.address == TAG_ADDRESS && shot.command == SHOT && !repeat && hits < LIVES) {
      hits++;
      hitUntil = now + HIT_MS;
      Serial.print(F("Hit! "));
      Serial.print(hits);
      Serial.print(F(" of "));
      Serial.println(LIVES);
      if (hits == LIVES) {
        Serial.println(F("Tagged out. Reset the board to play again."));
      }
    }
    IrReceiver.resume();
  }

  digitalWrite(HIT_PIN, now < hitUntil || hits >= LIVES ? HIGH : LOW);
}

// Laser tag: one player on an Arduino Nano. Put two (or more) on the canvas,
// each with this sketch, pointed at each other.
//
//   trigger button   D4 and GND (INPUT_PULLUP: a press reads LOW)
//   IR LED           D3 -> 220 ohm -> IR LED -> GND (IrSender's pin)
//   VS1838B          OUT -> D2, VCC -> 5V, GND -> GND
//   hit LED          D5 -> 220 ohm -> red LED -> GND
//
// Pressing the trigger fires one shot: an NEC frame, address 0x1A and
// command 0x01, flashed at 38 kHz through the infrared LED. Whichever
// receiver the LED is pointed at decodes it. Your own receiver faces the
// same way as your LED, so you never tag yourself.
//
// Each hit lights the red LED for a moment and goes to the Serial Monitor.
// Five hits and you are tagged out: the LED stays on and the trigger stops
// working until the board is reset.
//
// # One shot per press
//
// A shot is the moment the button goes from HIGH to LOW, and then the gun
// reloads for half a second, so holding the button fires once and a bounce
// of the contacts never fires twice.
//
// # Why 38 kHz
//
// The receiver ignores light that is just on: sunlight and lamps are full of
// infrared. It only answers light flashing at 38 kHz, which IrSender makes
// by switching the LED on and off 38,000 times a second through every burst
// of the frame.

#define DECODE_NEC  // the only protocol a shot uses: the other decoders stay out of flash
#include <IRremote.hpp>

const uint8_t RECEIVE_PIN = 2;
const uint8_t LED_PIN = 3;
const uint8_t TRIGGER_PIN = 4;
const uint8_t HIT_PIN = 5;

const uint16_t TAG_ADDRESS = 0x1A;
const uint8_t SHOT = 0x01;
const unsigned long RELOAD_MS = 500;
const unsigned long HIT_MS = 300;
const uint8_t LIVES = 5;

uint8_t hits = 0;
unsigned long reloadedAt = 0;
unsigned long hitUntil = 0;
bool wasPressed = false;

void setup() {
  Serial.begin(115200);
  pinMode(TRIGGER_PIN, INPUT_PULLUP);
  pinMode(HIT_PIN, OUTPUT);
  IrReceiver.begin(RECEIVE_PIN);
  IrSender.begin(LED_PIN);
  Serial.println(F("Laser tag: press the button to fire"));
}

void loop() {
  unsigned long now = millis();

  bool pressed = digitalRead(TRIGGER_PIN) == LOW;
  if (pressed && !wasPressed && now >= reloadedAt && hits < LIVES) {
    reloadedAt = now + RELOAD_MS;
    IrSender.sendNEC(TAG_ADDRESS, SHOT, 0);
    Serial.println(F("Fire!"));
  }
  wasPressed = pressed;

  if (IrReceiver.decode()) {
    IRData &shot = IrReceiver.decodedIRData;
    bool repeat = shot.flags & IRDATA_FLAGS_IS_REPEAT;
    if (shot.protocol == NEC && shot.address == TAG_ADDRESS && shot.command == SHOT && !repeat && hits < LIVES) {
      hits++;
      hitUntil = now + HIT_MS;
      Serial.print(F("Hit! "));
      Serial.print(hits);
      Serial.print(F(" of "));
      Serial.println(LIVES);
      if (hits == LIVES) {
        Serial.println(F("Tagged out. Reset the board to play again."));
      }
    }
    IrReceiver.resume();
  }

  digitalWrite(HIT_PIN, now < hitUntil || hits >= LIVES ? HIGH : LOW);
}