Published February 14, 2021 © CERN-OHL2

Race Starter,Timer and Speed Measure-Hot Wheels diecast cars

Race start sequence, then show winner for Hot Wheels diecast cars. Displays race time, both car real speed and winning difference in ms.

IntermediateFull instructions provided6,327

Race Starter,Timer and Speed Measure-Hot Wheels diecast cars

Things used in this project

Hardware components

Arduino Nano R3

5 mm LED: Green

5mm LED IR Receiver

5mm LED IR Emitter

Alphanumeric LCD, 16 x 2

Buzzer, Piezo

Wire, Wrapping Wire

Resistor 10k ohm

Resistor 220 ohm

Through Hole Resistor, 390 ohm

Resistor 100 ohm

Approx A3 Perspex coloured sheet

Hand tools and fabrication machines

Soldering iron (generic)

Solder Flux, Soldering

Multitool, Screwdriver

Saw

Story

Watch a short introduction video at:

Short video on what the Race Timer does

A more detailed guide on how to make this project is at:

Guide on how the timer works and how to make it

Our Hot Wheels Race Start and Finish Line Timer project is designed to show the winning car in a 2-car race contained in a child-friendly, easily transportable self-contained case that is less than 13x10x12cm. Simply place the unit over the tracks and connect a USB power supply. No additional set up is needed. The Race Timer starts with a grand prix style audible start sound and flashing light sequence. Once the lights go out, the race starts and the time is measured until the first light beam is broken. As the first car passes the sensors, the winning car's lane LED is immediately turned on providing instant visual confirmation of the winner. Once the second car finishes, the winning race time and time difference (in 1/1000 of a second) between the winning and losing car is displayed on the onboard LCD. The winning car will be detected up to Grand Prix times resolutions (0.001 of a second). After a short delay, the individual car’s actual speed measured through the gate is shown (Km/h), followed by the scale speed of each car (based on Hot Wheels scale of 1:64). The timer then resets for another race with the race start sound and lights sequence. If the second car does not pass the sensors within 10s of the first car passing the sensors, a crash is assumed and the winning lanes times and speeds are displayed before resetting for another race. The theoretical maximum real speed the unit can measure is 144Km/h with a time accuracy of +/- 2ms (based on Arduino Nano hardware).

Data can be transmitted to a computer via the USB serial interface to reveal more detailed information, including actual times in milliseconds. This could be used as a record in a Grand Prix style event or for comparing different cars characteristics.

The software can be quickly changed to a debugging mode by simply changing some of the CONST flags at the start of the code. Changing the value of COMP_OUTPUT improves the speed of simultaneous sensor detection of the unit by not outputting data to a computer. Setting the DEBUG flag provides the output of detailed debugging information, such as sensor readings, via the USB serial link. These will prove invaluable in setting up the unit for your individual hardware, but would unnecessarily slow the detection abilities if always on. Furthermore, the use of complier #if statements means that unwanted code is not compiled and uploaded to the Arduino. This reduces program space required and improves the execution speed of the program to further improve accuracy of your hardware.

Further development of the software has resulted in a dual function unit additionally capable of continuously displaying and recording the speed of cars passing the sensors or the race start/finish timer mode described above. This uses exactly the same hardware design as the basic version. You select which version, Race Timer or Speed Measurer, you want the hardware to run by simply swiping one of the rear sensors after powerup. As a Speed Measurer, the hardware is optimised to constantly monitor it's light sensors on both lanes to instantly record the speed of any car that crosses both the front and rear beams. Whilst the car is traversing the two light beams, the lane LED indicator is lit, followed by the instant display of the cars speed (Km/h) on the LCD screen. The speed of the Arduino Nano microprocessor and optimised software theoretically allows speeds up to 288 Km/h (real speed) to be detected. The displayed speed remains until it is replaced by the next car's speed after it traverses that lane.

Watch the videos for more information. You can now purchase a ready made Race Timer and Speedometer which will also dual function as Race Timer or continuous Speed Measurer for every passing car at:

https://www.cooksprojects.com

https://youtu.be/JraOIf4asYU

Don't forget that when constructing this project the IR detector LEDs are wired opposite to normal LEDs. The IR detector LEDs must have the long leg connected to GND via a 10KOhm pull down resistor and the detecting wire is connected onto the long leg before the resistor. Full details are in our workbook.

Code

Race Timer/Start Finish Line Code

// Hot Wheels Race Timer
// v2.0
// by Ian Cook
// Check our YouTube channel at Cooks Projects
// https://www.youtube.com/channel/UC5M_udtMhAwnymLyAY5qAkw
// Released Feb 2021 under licence
// Please acknowledge me if you use any of my code

// A further refined program that allows dual function of constant speed measurement as well as the race timer is available for additional fee.
// See website links or https://www.emmaalexandercook.com/cooks-projects/p/race-timer for details.

#include <I2CIO.h>
#include <FastIO.h>
#include <Wire.h>
#include <LCD.h>
#include <LiquidCrystal.h>
#include <LiquidCrystal_I2C.h>

LiquidCrystal_I2C lcd(0x27, 2, 1, 0, 4, 5, 6, 7, 3, POSITIVE); // double check your LCD address first using: i2C_scanner
//NANO uses SDA on A4 and SCL on A5


#define DEBUG false //Use to toggle the debug function on/off
#define DEBUG_SENSORS false //Use to toggle the sensor debug function
#define COMP_OUTPUT true //Use this to send info to a connected computer via serial interface. Use false if time is critical in detecting cars simultaneously
#define SPEED_CRITICAL false //Set to TRUE to improve detection speeds of the SpeedClock() function so that simultaneous detection of cars >20Km/h is always possible.

const int L_LANE_LED=10; //Lane 2 winning LED in D10 PIN
const int R_LANE_LED=11; //lane 1 winning LED on D11 PIN
const unsigned int MaxWaitTime=10000; //This is the maximum time to wait for second car to finish before recording result (millisecs)
const int buzzer=5; //Digital PIN buzzer is attached to - has to allow PWM (pin 3,5,6 or 9)

const int LEFT=1, RIGHT=2, BOTH=11;
const int RFDataIn = A1, RRDataIn = A3, LFDataIn = A0, LRDataIn = A2;  //Define the Anologue pins set up to which sensor. Reading Pin A3 causes Tone() to terminate early 
        //Beware NANO uses the LCD serial transmit (SDA,SCL) on pins A4 and A5
const int IRLEDThreshold = 800;   //Set to a value that indicates when the IR receiver is blocked. IR sensor returns 1024 at maximum brightness. Adjust for your configuration
const int DISTANCE_BETWEEN_SENSORS = 8; //set this to the distance (cm) between the front and rear IR sensor
const int L_LANE = 1, R_LANE = 2;
const int HIGH_TONE = 2400, LOW_TONE = 800;
const float SENSOR_DISTANCE_FACTOR  = float(288); // to speed up program, manually calculate this factor and place here. =float(DISTANCE_BETWEEN_SENSORS/100000)/float(0.27777778);
// SENSOR_DISTANCE_FACTOR is 288 if the DISTANCE_BETWEEN_SENSORS is 8cm

int FrontSensor[2], RearSensor[2]; //For recording the sensor information and allowing all subroutines to be able to read them. 
// Although array[0] should be available, my analysis shows that using array[0] is unreliable when using global variables.


void setup() {

  Serial.begin(9600);
  pinMode(RFDataIn, INPUT);
  pinMode(RRDataIn, INPUT);
  pinMode(LFDataIn, INPUT);
  pinMode(LRDataIn, INPUT);

  pinMode(R_LANE_LED, OUTPUT); //lane 1
  pinMode(L_LANE_LED, OUTPUT); //lane 2

  pinMode(buzzer, OUTPUT); // Set buzzer - as an output
  
  digitalWrite(R_LANE_LED, HIGH);
  digitalWrite(L_LANE_LED, HIGH);

  lcd.begin(16, 2);
  lcd.setCursor(3, 0);
  lcd.print("Race Timer");
  lcd.setCursor(3, 1);
  lcd.print("by:Ian Cook");
  delay(2000);
  lcd.clear();
}

void loop() {
 int Winner;
 bool R_LANEFinish, L_LANEFinish, R_LANESpeedTrap, L_LANESpeedTrap, Sound;
 float LSpeed, LScaleSpeed=0, RSpeed, RScaleSpeed=0, WinningDiff, RaceTime;
 unsigned long StartTime, WaitTime, SampleTime, timediff;
 unsigned long FrontSensorTime[2],  RearSensorTime[2]; //Using array[0] results in a bug with global variables in the compilier, so I haven't used array[0]
 

  // Race reset - so reset variable values
  FrontSensorTime[L_LANE]= 0;
  FrontSensorTime[R_LANE]= 0;
  RearSensorTime[L_LANE] = 0;
  RearSensorTime[R_LANE] = 0;
  Winner = 99;
  LSpeed = 0;
  RSpeed = 0;
  WinningDiff = 999.999;
  RaceTime = 0;
  timediff =9999;
  R_LANEFinish = false;
  L_LANEFinish = false;
  R_LANESpeedTrap = false;
  L_LANESpeedTrap = false;

  //Flash lights,sound buzzer and declare we are ready to race
  lcd.clear();
  lcd.setCursor(3, 0);
  lcd.print("Race Timer ");
  delay(2000);
  lcd.setCursor(0, 1);
  lcd.print("Ready to race...");
  digitalWrite(R_LANE_LED, LOW);
  digitalWrite(L_LANE_LED, LOW);
  tone(buzzer, LOW_TONE, 600); 
  delay(900); 
  tone(buzzer, LOW_TONE,600);
  digitalWrite(L_LANE_LED, HIGH); 
  delay(900);
  tone(buzzer, LOW_TONE,600);
  digitalWrite(R_LANE_LED,HIGH);
  delay(900);
  tone(buzzer, HIGH_TONE,800);
  digitalWrite(R_LANE_LED, LOW);
  digitalWrite(L_LANE_LED, LOW);
  Sound = true; //flag to allow tone to sound as workaround for Arduino bug that stops tone when pin A3 is read! 
  lcd.clear();
  lcd.setCursor(4,0); 
  lcd.print("GO GO GO!");
  StartTime = millis();  //set the start time of the race which begins when lights go out

  WaitTime = StartTime;  //Set this so that we don't wait for ever for a finishing car that has crashed

// Loop to wait until the first car crosses - the do Loop takes 1-2 ms which means speeds over 144 Km/h will sometimes not be read. 288km/h is the max theoretical speed detectable on Arduino Nano
  do {  
//Read the sensor data and record the time
  SampleTime = SampleSensors(Sound);
    if (Sound && SampleTime>(StartTime+800)) Sound = false;  //Workaround for Tone bug that stops tone when pin A3 read!
    
//Set DEBUG flag for your setup to make sure the constant IRLEDThreshold value is accurate for your hardware
//If DEBUG is left true then these serial prints will slow the sample rate considerably and reduce the max detectable speed to approx 7Km/h
 #if (DEBUG) 
   TestSensors(false);  //Debug routine to display the sensor recorded state
 #endif
           
    if (!L_LANEFinish && (FrontSensor[L_LANE] < IRLEDThreshold)) {
      // Left Lane has finished
      FrontSensorTime[L_LANE] = SampleTime;
      if (!R_LANEFinish) {
        //As the other lane hasn't finished yet, this lane is the winner
        Winner = L_LANE;
        digitalWrite(L_LANE_LED, HIGH);
       }
      L_LANEFinish = true;
      WaitTime = millis();  //Reset the timer to ensure we don't wait if the other lane has crashed
     }
    if (!R_LANEFinish && (FrontSensor[R_LANE] < IRLEDThreshold)) {
      // Right Lane has finished
      FrontSensorTime[R_LANE] = SampleTime;
      if (!L_LANEFinish) {
        //As the other lane hasn't finished yet, this lane is the winner
        Winner = R_LANE;
        digitalWrite(R_LANE_LED, HIGH);
       }
      R_LANEFinish = true;
      WaitTime = millis(); //Reset the timer to ensure we don't wait if the other lane has crashed
     }
      
    if (L_LANEFinish && !L_LANESpeedTrap && RearSensor[L_LANE] < IRLEDThreshold) {
      //The car has crossed the line and now the rear sensor
      RearSensorTime[L_LANE] = SampleTime;
      L_LANESpeedTrap = true;
    }
    if (R_LANEFinish && !R_LANESpeedTrap && RearSensor[R_LANE] < IRLEDThreshold) {
      //The car has crossed the line and now the rear sensor
      RearSensorTime[R_LANE] = SampleTime;
      R_LANESpeedTrap = true;
    }
// Exit the loop once all sensors have been triggered or once one lane has finished and there has been a delay > MaxWaitTime   
  } while (!((L_LANEFinish && R_LANEFinish && L_LANESpeedTrap && R_LANESpeedTrap) || ((L_LANEFinish || R_LANEFinish) && (millis() - WaitTime > MaxWaitTime)) ) );

  tone(buzzer, HIGH_TONE,150);
  delay(200);
  tone(buzzer, HIGH_TONE,150);
    
// Send information to a connected computer which can be used in data analysis
#if (COMP_OUTPUT)
    Serial.println("Times:\tLEFT Front,\tRear,\tRIGHT Front,\tRear");
    Serial.print("\t");
    Serial.print(FrontSensorTime[L_LANE]);
    Serial.print("\t");
    Serial.print(RearSensorTime[L_LANE]);
    Serial.print("\t\t");
    Serial.print(FrontSensorTime[R_LANE]);
    Serial.print("\t");
    Serial.println(RearSensorTime[R_LANE]);
#endif
//Race is over.  Calculate and display times
//Race Time is time for first car to finish

switch (Winner) {
  case R_LANE:
    RaceTime = float (FrontSensorTime[R_LANE]-StartTime)/1000; //Recorded in Sec
    if (FrontSensorTime[L_LANE]>0) WinningDiff = float(FrontSensorTime[L_LANE] - FrontSensorTime[R_LANE])/1000;   
   break;
  case L_LANE:
   RaceTime = float (FrontSensorTime[L_LANE]-StartTime)/1000;
   if (FrontSensorTime[R_LANE]>0) WinningDiff = float(FrontSensorTime[R_LANE] - FrontSensorTime[L_LANE])/1000;
   break;
  default:
   RaceTime = 0;
}

 //Check for a draw due to sample timings being equal
 if (WinningDiff == 0) Winner=555;
   
//The distance between the sensors is DistanceBetweenSensors (cm) so the speed is D cm/time taken (cm/ms *3 600 000 / 100 000 = km/h) :: Millis() returns milliseconds which 1/1000 s
// Km/h = (D/100000)/(milli/(1000*60*60)) = D/(milli/3600) or D/3600 * 1/milli; D=8 then km/h = 288 / milli
//Max speed capable of reading at 2ms sample rate is  144 Km/h!
// Speed = Dist in KM (cm /100000)  / time in hrs ( millis/1000/60/60) 
// distance = 8 cm then Speed = (8/100000)/(millis/.27777778) = (0.00008/0.27777778)/millis = 288/millis

  timediff = RearSensorTime[L_LANE] - FrontSensorTime[L_LANE];
  if (timediff>0) {
   LSpeed = SENSOR_DISTANCE_FACTOR / float(timediff); //km/h
   #if (DEBUG) 
    //Use to check that the SENSOR_DISTANCE_FACTOR is correct for your set up
    Serial.print ("Time Diff:\t");
    Serial.print (timediff);
    Serial.print (" Lspeed calc ");
    Serial.println (LSpeed);
    #endif
  }
  else LSpeed = 0;

  timediff = RearSensorTime[R_LANE] - FrontSensorTime[R_LANE];
  if (timediff>0) {
    RSpeed = SENSOR_DISTANCE_FACTOR / float(timediff); //km/h
    #if (DEBUG)
      //Use to check that the SENSOR_DISTANCE_FACTOR is correct for your set up
      Serial.print ("Time Diff:\t");
      Serial.print (timediff);
      Serial.print (" Rspeed calc ");
      Serial.println (RSpeed);
    #endif
  }
  else RSpeed = 0;

//Hot wheels cars are 1:64 scale so calculate scale speed
  LScaleSpeed=LSpeed*float(64);
  RScaleSpeed=RSpeed*float(64);

//Send information to serial device (computer) for data analysis
 #if (COMP_OUTPUT) 
  Serial.print("Race Time: ");
  Serial.println(RaceTime);
  Serial.println("Final Speeds");
  Serial.print("LEFT:  ");
  Serial.print(LSpeed,3);
  Serial.print(" Km/h : Scale Spd= ");
  Serial.print(LScaleSpeed,2);
  Serial.println(" Km/h");
  Serial.print("RIGHT: ");
  Serial.print(RSpeed,3);
  Serial.print(" Km/h : Scale Spd= ");
  Serial.print(RScaleSpeed,2);
  Serial.println(" Km/h");

  Serial.print("Left  Lane Race Time (ms)");
  Serial.println("\tRight Lane Race Time (ms)");
  Serial.print(FrontSensorTime[L_LANE]);
  Serial.print("\t\t\t");
  Serial.println(FrontSensorTime[R_LANE]);
  if (Winner== 555) Serial.print("This was a DRAW! ");
    else if (Winner == R_LANE) Serial.print("Right car won by ");
         else Serial.print("Left car won by ");
  Serial.print(WinningDiff,3);
  Serial.println(" s");
 #endif
 
//Send the information to the LCD display on the hardware unit
  lcd.clear();
  lcd.setCursor(0,0);
  lcd.print("Race Time:");
  lcd.setCursor(10,0);
  lcd.print(RaceTime,3);
  lcd.setCursor(14,0);
  lcd.print("s ");
  lcd.setCursor(0,1);
  if (Winner == L_LANE) {
    lcd.print("L won by");
    }
  else if (Winner == R_LANE) {
    lcd.print("R won by");
    }
    else {
      lcd.print("DRAW!");
   }
  lcd.setCursor(10,1);
  lcd.print(WinningDiff,3);
  lcd.setCursor(15,1);
  lcd.print("s");
  delay(5000);
    
  lcd.clear();
  lcd.setCursor(0, 0);
  lcd.print("LSpd:");
  lcd.setCursor(5, 0);
  if (LSpeed > 0.001) {
    lcd.print(LSpeed, 2);  
    lcd.setCursor(11, 0);
    lcd.print(" Km/h");
   }
   else lcd.print("  * DNF *");  //This lane did not finish
  lcd.setCursor(0, 1);
  lcd.print("RSpd:" );
  lcd.setCursor(5, 1);
  if (RSpeed > 0.001) {
    lcd.print(RSpeed, 2);  
    lcd.setCursor(11, 1);
    lcd.print(" Km/h");
   }
   else lcd.print("  * DNF *");  //This lane did not finish

  if (Winner != 555) {
    //i.e. This is NOT a draw
    //set cursor for Winnner text
    delay(1000);
    lcd.setCursor(11, (Winner-L_LANE));
    lcd.print("*WIN*");
    for (int i=0; i<6; i++) {
      digitalWrite(Winner+9, LOW);
      delay(400);
      digitalWrite(Winner+9, HIGH);
      delay(400);
      }
   }
   else {
   //This must be a draw
    lcd.setCursor(12,0);
    lcd.print ("DRAW");
    lcd.setCursor(12,1);
    lcd.print ("DRAW");
    for (int i=0; i<6; i++) {
     digitalWrite(L_LANE, LOW);
     digitalWrite(R_LANE, LOW);
     delay(400);
     digitalWrite(R_LANE, HIGH);
     digitalWrite(L_LANE, HIGH);
     delay(400);
     }   
    }

   lcd.clear();
   lcd.setCursor(0, 0);
   lcd.print("LScaleSpd:");
   if (LScaleSpeed<10)   lcd.setCursor(12,0);
    else {
      if (LScaleSpeed<100)  lcd.setCursor(11, 0); //line up the decimal points on the display
      else lcd.setCursor(10,0);
    }
   if (LScaleSpeed >0) lcd.print(LScaleSpeed, 1);
     else lcd.print("DNF");
   lcd.setCursor(0, 1);
   lcd.print("RScaleSpd:");
   if (RScaleSpeed<10)   lcd.setCursor(12,1);
    else {
      if (RScaleSpeed<100)  lcd.setCursor(11, 1); //line up the decimal points on the display
      else lcd.setCursor(10,0);
    }
   if (RScaleSpeed >0) lcd.print(RScaleSpeed, 1);
     else lcd.print("DNF");

  // Delay before staring the race again.
  delay(5000);
}


unsigned long SampleSensors(bool sound) {
//Read the sensor data and return the time they are taken (ms)
//The parameter sound is used to prevent the tone being terminated early due to Arduino Nano issue that reading A3 pin causes the tone to stop!
  FrontSensor[R_LANE] = analogRead(RFDataIn);
  FrontSensor[L_LANE] = analogRead(LFDataIn);
//This section only compiles the relevant code if RRDataIn is connected to pin A3, defined in constants. This is to prevent cutting tone short during start sequence
#if RRDataIn == A3
  if (!sound) RearSensor[R_LANE] = analogRead(RRDataIn);
#else
    RearSensor[R_LANE] = analogRead(RRDataIn); 
#endif
  RearSensor[L_LANE] = analogRead(LRDataIn);
  return(millis());
}

Credits

cooksprojects

0 projects • 5 followers

Race Starter,Timer and Speed Measure-Hot Wheels diecast cars

Things used in this project

Hardware components

Hand tools and fabrication machines

Story

Schematics

speedtraplogo_575uywYBWU.png

Code

Race Timer/Start Finish Line Code

Credits

cooksprojects

Comments

Embed the widget on your own site

Race Starter,Timer and Speed Measure-Hot Wheels diecast cars

Race Starter,Timer and Speed Measure-Hot Wheels diecast cars

Things used in this project

Hardware components

Hand tools and fabrication machines

Story

Schematics

speedtraplogo_575uywYBWU.png

Code

Race Timer/Start Finish Line Code

Credits

cooksprojects

Comments

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