// Carrera race track timer
//
// Lap timing for a Carrera slot car racing track using an Arduino Uno
// and two reed switches to detect the magnet of the cars.
// The lap counts, current lap times and lap records are displayed on a 16x2 LCD.
// Lap counters and timers can be reset with a pushbutton.
//
// Author: Patrick Sturm
// January 2019
//
// Revision 2.0 by Spork. TEST VERSION - LANE 2 DISABLED
// September 2024
// Changes: revised for Photodiode operation. Pin 3 provides 5v for Photodiode gates, 
// Known Bugs: Pin 10 for reset doesn't work.

#include <LiquidCrystal.h>

// initialize the LCD
LiquidCrystal lcd(9, 8, 7, 6, 5, 4);

// initialize variables
unsigned long lastTriggerTime[2];  // arrays of length 2 for the two cars
volatile unsigned long triggerTime[2];
volatile boolean triggered[2];
volatile boolean reset = false;
int lapNumber[2] = {0, 0};
unsigned long lapTime[2], clock[2];
unsigned long lapRecord[2] = {0, 0};
boolean first[2] = {true,  true};
int notes[] = {1047, 1319, 1568};  // frequencies for tone(), notes: C6, E6, G6
int senRead=0;
int senRead1=1;  

// string buffers for LCD
// (see https://www.baldengineer.com/arduino-lcd-display-tips.html)
char line[2][17];
char fstr_lapTime[2][7];
char fstr_lapRecord[2][7];

// interrupt service routines
void isr1() {
  //int trig1 = analogRead(senRead);
  //if (trig1 > 500) return;  // wait until trigger is noticed in loop()
  triggerTime[0] = millis();
  triggered[0] = true;
}
void isr2() {
  if (triggered[1]) return;
  triggerTime[1] = millis();
  triggered[1] = true;
}
// pin change interrupt (as there are only 2 external interrupts on the Uno)
// (see http://gammon.com.au/interrupts, https://thewanderingengineer.com/2014/08/11/arduino-pin-change-interrupts/)
//ISR(PCINT0_vect) {  // Port B, PCINT0 - PCINT7
//  if (reset) return;
//  reset = true;
//}

void setup() {
  //int limit=500;
  //pinMode(2, INPUT_PULLUP);  // interrupt pin for reed switch 1
  //pinMode(3, INPUT_PULLUP);  // interrupt pin for reed switch 2
  //attachInterrupt(digitalPinToInterrupt(2), isr1, FALLING);
  //attachInterrupt(digitalPinToInterrupt(3), isr2, FALLING);
//  pinMode(10, INPUT_PULLUP);  // pin for push putton
  pinMode(3,OUTPUT);
  digitalWrite(3, HIGH); //pin for power for Photodiode
  //PCMSK0 |= 0b00000100;  // mask to turn on pin D10, PCINT3. PCMSK0 |= bit (PCINT2);
  //PCIFR  |= bit (PCIF0);  // clear all interrupt flags
  //PCICR |= 0b00000001;  // enable pin change interrupts for D8 to D13. PCICR  |= bit (PCIE0);
  pinMode(11, OUTPUT);  // pin for piezo buzzer

  lcd.begin(20, 4);  // set up the number of columns and rows on the LCD
  lcd.print((char)0x84);  // 0x84 = ä, 0x8E = Ä, 0x94 = ö, 0x99 = Ö, 0x81 = ü, 0x9A = Ü
  lcd.setCursor(0, 1);  // set the cursor to column 0, line 1
  lcd.print("ScumTesties");

  // switch LED_BUILTIN off
  pinMode(LED_BUILTIN, OUTPUT);
  digitalWrite(LED_BUILTIN, LOW);

  delay(3000);  // show starting message for 3 s
}

void loop() {
  int limit=500; // set trigger value here, expected range, constant 0 then 1023 when sensor obscured
  int lane1=analogRead(senRead);
  int lane2=analogRead(senRead1);
    if(lane1 >= limit)              //lane 1 trigger
  {  
    isr1();  
  } 
  //if(lane2 >= limit)   // lane 2 trigger DISABLED, Remove comment markers
  //{
  //  isr2();
  //}
  for (int i = 0; i < 2; i++) {  // loop over the two cars
    // if reed switch is triggered
    if (triggered[i]) {
      // ignore if lap time is too short, debouncing
      if ((triggerTime[i] - lastTriggerTime[i]) < 2000.0) {
        triggered[i] = false;
        return;
      }

      if (first[i]) {  // first trigger to start the timer
        lastTriggerTime[i] = triggerTime[i];
        triggered[i] = false;
        first[i] = false;
        return;
      }

      lapTime[i] = (triggerTime[i] - lastTriggerTime[i]);
      lapTime[i] = min(lapTime[i], 999990);  // maximum is 999.99 s
      lastTriggerTime[i] = triggerTime[i];
      triggered[i] = false;  // re-arm for next time
      lapNumber[i]++;
      lapNumber[i] %= 100;  // count up to 99
      if (lapTime[i] < lapRecord[i] || lapRecord[i] == 0) {
        lapRecord[i] = lapTime[i];
      }

      if (lapNumber[i] % 10 == 0) {  // play sound every 10 laps
        for (int j = 0; j < 3; j++) {
          tone(11, notes[i*j+(i-1)*(j-2)], 200);
          delay(50);
        }
      }
    }
  }

  // reset lap counter and best time
  if (reset) {
    for (int j = 0; j < 2; j++) {
      lapNumber[j] = 0;
      lapRecord[j] = 0;
      first[j] = true;
      lapTime[j] = 0;
    }
    reset = false;
  }

  // update LCD
  updateDisplay();

  // wait for 0.001 s
  delay(1);
}

// update display function
void updateDisplay() {
  for (int i = 0; i < 2; i++) {  // loop over the the two lines of the LCD
    // lap clocks
    clock[i] = (millis() - triggerTime[i]);

    // generate display strings
    dtostrf(lapRecord[i]/1000.0, 6, 2, fstr_lapRecord[i]);
    // (see https://www.microchip.com/webdoc/AVRLibcReferenceManual/group__avr__stdlib_1ga060c998e77fb5fc0d3168b3ce8771d42.html)
    if (clock[i] < 3000 || first[i]) {  // print last lap time for first 3 s
      dtostrf(lapTime[i]/1000.0, 6, 2, fstr_lapTime[i]);
      sprintf(line[i], "%2d %6s %6s", lapNumber[i], fstr_lapRecord[i], fstr_lapTime[i]);
    } else {
      sprintf(line[i], "%2d %6s %5ds", lapNumber[i], fstr_lapRecord[i], clock[i]/1000);
    }

    lcd.setCursor(0, i);
    lcd.print(line[i]);
    lcd.setCursor(0,4); // Debug info
    int val=analogRead(senRead);
    lcd.print("A0 value is     "); // block out any previous values
    lcd.setCursor(12,4); 
    lcd.print(val);
  }
}