Speeduino - Speed Tracker

1/* Speed Test for Hot Wheels(R) die cast toy cars.
2
3 IR LEDs with  220ohms resistors. IR sensor without any resistor.
4 
5 This project works ok  at the bench when you throw the car smoothly.
6 But in the "real world" of a  Hot Wheels tracks the sensors are not fast reading enough. Please share your 
7  improvements if you find a more precise and fast reading sensors!
8 
9 Project  creator Fabio Coelho - Rio de Janeiro - Brazil Dec2018.
10 
11 Some improvements  were made following inputs from fellow members at Arduino Project hub. Thank You!
12  
13 
14 */
15
16#include <LiquidCrystal_I2C.h>
17//We use a LCD 20x4 with an  I2C module. It really keeps wiring simple...
18#include <Wire.h>
19
20LiquidCrystal_I2C  lcd(0x27,20,4);// I2C adress
21
22const int ledPin = 12;
23byte irPinA = 4;
24byte  irPinB = 5;
25byte irValA;
26byte irValB;
27float diff; // store timeScnd minus  timeFirst
28float vel; // calculated speed
29unsigned long timeFirst;// IR sensor  at irPinA
30unsigned long timeScnd;// IR sensor at irPinB
31float speedConst =  453.6; // ((distance between IR sensors in mm) x 3600)/1000)to convert mm/millis  to km/h) 
32                          // In This project we have 126mm between  IR sensors
33
34
35byte customChar0[8] = { //some art for the LCD screen
36B01000,
37B01100,
38B01110,
39B01111,
40B01110,
41B01100,
42B01000,
43B00000
44};
45
46void  configLCD(){ //function to config the LCD display
47 
48lcd.createChar(0, customChar0);
49lcd.setCursor(0,0);
50lcd.write(0);
51lcd.write(0);
52lcd.write(0);
53lcd.write(0);
54lcd.write(0);
55lcd.setCursor(5,0);
56lcd.print("SPEED  TEST");
57lcd.setCursor(15,0);
58lcd.write(0);
59lcd.write(0);
60lcd.write(0);
61lcd.write(0);
62lcd.write(0);
63lcd.setCursor(0,1);
64lcd.print("P1:");
65lcd.setCursor(0,2);
66lcd.print("P2:");
67lcd.setCursor(0,3);
68lcd.print("Speed:");
69
70}
71
72void  setup()
73{
74pinMode(irPinA, INPUT);
75pinMode(irPinB, INPUT);
76pinMode(ledPin,  OUTPUT);
77//Serial.begin(9600);noneededt 
78lcd.init();
79lcd.backlight();
80configLCD();
81digitalWrite(ledPin,  HIGH); //Green LED HIGH: ok to next ride.
82
83}//end setup
84
85
86void loop()
87{
88  irValA = digitalRead(irPinA);
89  irValB = digitalRead(irPinB);
90 
91  if  (irValA == LOW){
92      timeFirst = millis();
93     digitalWrite(ledPin, LOW);
94    delay(30);
95    }
96 
97  if (irValB == LOW){
98    timeScnd = millis();
99    diff = timeScnd - timeFirst; 
100    vel = speedConst / diff;//get the Speed  converted from mm/millis to km/h.
101    /* 
102    use only if you want
103        Serial.print("T1:  ");
104    Serial.println(timeFirst);
105    Serial.print("T2: ");
106    Serial.println(timeScnd);
107    Serial.print("Diff: ");
108    Serial.println(diff);
109    Serial.print("Speed:  ");
110    Serial.println(vel);
111    */
112    
113    lcd.setCursor(6, 1);
114    lcd.print(timeFirst);
115    lcd.setCursor(6, 2);
116    lcd.print(timeScnd);  
117    lcd.setCursor(6,3);
118    lcd.print(vel);
119    lcd.print("km/h");
120       delay(5000); 
121       lcd.clear();
122       configLCD();
123       digitalWrite(ledPin,  HIGH);
124        }
125    
126}//end Loop