Concept:
2 IR Detector’s connected to an Arduino Microcontroller listen for 10 pulses from a TV remote coming at 38khz to avoid sun light interference.
If 10 pulses are counted then the Arduino will blink the LED’s 3 times. This tells the racer that the TV remote signal has been received.
A short delay gives time to store the TV remote and to focus on the actual Race start.
The start sequence works similar to an F1 or German Touring Car start. The LED’s come on one at a time with a short delay and go all out at the same time which is the start of the race.
The Arduino resets after the start sequence and waits for 10 pulses again to start the next starting sequence.
Due to the fact that the IR LED’s are pulsed they can be “over driven” as far as current goes – which is the reason why a TV remote works from easily 20-30 feet away.

Video:

Items List:
LED’s
220Ohm Resistors (one for each LED)
Arduino Microcontroller
IR Detectors 38Khz
Costco Apple Packaging
9 Volt Battery
20 or 18 Gage Cable

Tools:
Drill
Soldering Iron
Hot Glue Gun

Total Cost: $40
Time: 4 hours

If you are an Arduino Expert or if you are a “Real” Programmer you will probably get a good laugh out of my code. But hey it works.
I noticed that when I run the Arduino on Battery it tends to pick up noise from the IR Detectors. I was trying to let it time out – say if there is no second pulse detected after 1 second ignore the first pulse cause it is likely noise. Unfortunately I did not get it to work. So instead I have it programmed that it needs to see 10 pulses from the TV remote before a starting sequence is initiated. The Serial print commands helped me during the build and for troubleshooting. They are not essential to the function of the race starting lights.

Here is the complete Arduino Code:

//F1 Style Starting Lights

// Set pin numbers:
const int ledPin2 = 2; // LED 1 connected to digital pin 2
const int ledPin3 = 3; // LED 2 connected to digital pin 3
const int ledPin4 = 4; // LED 3 connected to digital pin 4
const int ledPin5 = 5; // LED 4 connected to digital pin 5

const int ledPin6 = 6; // LED 5 connected to digital pin 6
const int ledPin7 = 7; // LED 6 connected to digital pin 7
const int ledPin8 = 8; // LED 7 connected to digital pin 8
const int ledPin9 = 9; // LED 8 connected to digital pin 9

const int buttonPin = 12; // IR Detector connected to digital pin 12
const int ledPin = 13; // Onboard LED flashes when IR Detector sees beam & stays lit for entire loop

// Variables that will change:
int buttonPushCounter = 0; // counter for the number of button presses
int buttonState = 0; // current state of the button
int lastButtonState = 0; // previous state of the button

const int flasher = 200; // Delay of 250 mili seconds for IR signal detected & start sequence initialised
const int ready = 3500; // Delay of 3.5 seconds mili seconds before start sequence
const int timer = 1500; // Delay of 1.5 seconds between starting lights

void setup()
{

// Initialize the LED pins as an output:
pinMode(ledPin2, OUTPUT); // Sets the digital pin as output
pinMode(ledPin3, OUTPUT); // Sets the digital pin as output
pinMode(ledPin4, OUTPUT); // Sets the digital pin as output
pinMode(ledPin5, OUTPUT); // Sets the digital pin as output

pinMode(ledPin6, OUTPUT); // Sets the digital pin as output
pinMode(ledPin7, OUTPUT); // Sets the digital pin as output
pinMode(ledPin8, OUTPUT); // Sets the digital pin as output
pinMode(ledPin9, OUTPUT); // Sets the digital pin as output

pinMode(ledPin, OUTPUT); // Sets IR check LED digital pin as output

// initialize the pushbutton pin as an input:
pinMode(buttonPin, INPUT); //Sets the digitalpin for the button as input

// initialize serial communication – only used for troubleshooting
Serial.begin(9600);

}
void loop()
{

// read the IR Detector input pin:
buttonState = digitalRead(buttonPin);

// compare the buttonState to its previous state
if (buttonState != lastButtonState) {
// if the state has changed, increment the counter
if (buttonState == HIGH) {
// if the current state is HIGH then the button
// wend from off to on:
buttonPushCounter++;
Serial.println(“on”);
Serial.print(“number of button pushes: “);
Serial.println(buttonPushCounter, DEC);
}
else {
// if the current state is LOW then the button
// wend from on to off:
Serial.println(“off”);
}
}
// save the current state as the last state,
//for next time through the loop
lastButtonState = buttonState;

// turns on the LED 13 and Starting Lights every 10 button pushes by
// checking the modulo of the button push counter.
// the modulo function gives you the remainder of
// the division of two numbers:
if (buttonPushCounter % 10 == 0) {

digitalWrite(ledPin, HIGH);

{
if (ledPin == HIGH);
{
Serial.println(“High”);

// Confirm buttonState HIGH by flashing all LED’s 5 times
digitalWrite(ledPin2, HIGH); // sets LED 1 on
digitalWrite(ledPin4, HIGH); // sets LED 2 on
digitalWrite(ledPin6, HIGH); // sets LED 3 on
digitalWrite(ledPin8, HIGH); // sets LED 4 on
delay(flasher);
digitalWrite(ledPin2, LOW); // sets LED’s off
digitalWrite(ledPin4, LOW);
digitalWrite(ledPin6, LOW);
digitalWrite(ledPin8, LOW);
delay(flasher);
digitalWrite(ledPin3, HIGH); // sets LED 5 on
digitalWrite(ledPin5, HIGH); // sets LED 6 on
digitalWrite(ledPin7, HIGH); // sets LED 7 on
digitalWrite(ledPin9, HIGH); // sets LED 8 on
delay(flasher);
digitalWrite(ledPin3, LOW); // sets LED’s off
digitalWrite(ledPin5, LOW);
digitalWrite(ledPin7, LOW);
digitalWrite(ledPin9, LOW);
delay(flasher);
digitalWrite(ledPin2, HIGH); // sets LED 1 on
digitalWrite(ledPin4, HIGH); // sets LED 2 on
digitalWrite(ledPin6, HIGH); // sets LED 3 on
digitalWrite(ledPin8, HIGH); // sets LED 4 on
delay(flasher);
digitalWrite(ledPin2, LOW); // sets LED’s off
digitalWrite(ledPin4, LOW);
digitalWrite(ledPin6, LOW);
digitalWrite(ledPin8, LOW);
delay(flasher);
digitalWrite(ledPin3, HIGH); // sets LED 5 on
digitalWrite(ledPin5, HIGH); // sets LED 6 on
digitalWrite(ledPin7, HIGH); // sets LED 7 on
digitalWrite(ledPin9, HIGH); // sets LED 8 on
delay(flasher);
digitalWrite(ledPin3, LOW); // sets LED’s off
digitalWrite(ledPin5, LOW);
digitalWrite(ledPin7, LOW);
digitalWrite(ledPin9, LOW);
delay(flasher);
digitalWrite(ledPin6, LOW); // sets LED’s off
digitalWrite(ledPin7, LOW);
digitalWrite(ledPin8, LOW);
digitalWrite(ledPin9, LOW);
delay(flasher);
digitalWrite(ledPin2, HIGH); // sets LED 1 on
digitalWrite(ledPin3, HIGH); // sets LED 2 on
digitalWrite(ledPin4, HIGH); // sets LED 3 on
digitalWrite(ledPin5, HIGH); // sets LED 4 on
digitalWrite(ledPin6, HIGH); // sets LED 5 on
digitalWrite(ledPin7, HIGH); // sets LED 6 on
digitalWrite(ledPin8, HIGH); // sets LED 7 on
digitalWrite(ledPin9, HIGH); // sets LED 8 on
delay(flasher);
digitalWrite(ledPin2, LOW); // sets LED’s off
digitalWrite(ledPin3, LOW);
digitalWrite(ledPin4, LOW);
digitalWrite(ledPin5, LOW);
digitalWrite(ledPin6, LOW);
digitalWrite(ledPin7, LOW);
digitalWrite(ledPin8, LOW);
digitalWrite(ledPin9, LOW);
delay(flasher);
digitalWrite(ledPin2, HIGH); // sets LED 1 on
digitalWrite(ledPin3, HIGH); // sets LED 2 on
digitalWrite(ledPin4, HIGH); // sets LED 3 on
digitalWrite(ledPin5, HIGH); // sets LED 4 on
digitalWrite(ledPin6, HIGH); // sets LED 5 on
digitalWrite(ledPin7, HIGH); // sets LED 6 on
digitalWrite(ledPin8, HIGH); // sets LED 7 on
digitalWrite(ledPin9, HIGH); // sets LED 8 on
delay(flasher);
digitalWrite(ledPin2, LOW); // sets LED’s off
digitalWrite(ledPin3, LOW);
digitalWrite(ledPin4, LOW);
digitalWrite(ledPin5, LOW);
digitalWrite(ledPin6, LOW);
digitalWrite(ledPin7, LOW);
digitalWrite(ledPin8, LOW);
digitalWrite(ledPin9, LOW);
delay(ready);

// Turn LEDs on – initiate Starting Sequence:
digitalWrite(ledPin2, HIGH); // sets the LED 1 on
digitalWrite(ledPin3, HIGH); // sets the LED 2 on
delay(timer); // waits for 1.5 seconds

digitalWrite(ledPin4, HIGH); // sets the LED 3 on
digitalWrite(ledPin5, HIGH); // sets the LED 4 on
delay(timer); // waits for 1.5 seconds

digitalWrite(ledPin6, HIGH); // sets the LED 5 on
digitalWrite(ledPin7, HIGH); // sets the LED 6 on
delay(timer); // waits for 1.5 seconds

digitalWrite(ledPin8, HIGH); // sets the LED 7 on
digitalWrite(ledPin9, HIGH); // sets the LED 8 on
delay(timer); // waits for 1.5 seconds

digitalWrite(ledPin2, LOW); // sets the LED 1 off
digitalWrite(ledPin3, LOW); // sets the LED 2 off
digitalWrite(ledPin4, LOW); // sets the LED 3 off
digitalWrite(ledPin5, LOW); // sets the LED 4 off
digitalWrite(ledPin6, LOW); // sets the LED 5 off
digitalWrite(ledPin7, LOW); // sets the LED 6 off
digitalWrite(ledPin8, LOW); // sets the LED 7 off
digitalWrite(ledPin9, LOW); // sets the LED 8 off

{
if (ledPin9 == LOW);
{
Serial.println(“LOW”);
}

}
}
}

buttonPushCounter = 1; //reset
Serial.println(“Reset”);
}
else {
// turn LEDs off:
digitalWrite(ledPin2, LOW);
digitalWrite(ledPin3, LOW);
digitalWrite(ledPin4, LOW);
digitalWrite(ledPin5, LOW);
digitalWrite(ledPin6, LOW);
digitalWrite(ledPin7, LOW);
digitalWrite(ledPin8, LOW);
digitalWrite(ledPin9, LOW);
digitalWrite(ledPin, LOW);
}
}

BUT… turns out that my Rally car is “loosing paint” and the laser shines right through the body and triggers the software to count the car 2-3 times each time it comes by.

I also wanted to keep setup time to a very minimum and decided to built a mechanical contact that would simply trigger when the car drives over.

This setup worked like a charm UNTIL later on in the day when tiny little rocks and dust coated the contacts and prohibited proper conductivity of the two plates. That was the end of the mechanical lap counter and timer.

My latest idea is to use a webcam as input device – and so far it works like a charm. I initially messed around writing my own software, but similar as to my previous phototransistor- via-gameport timer I found that someone already had the idea before me and did a much better job compared to what my coding skills would have allowed me to do. Long story short I am currently running EasyLapCounter – check out the site and developer -. The software works like a charm and the software can even count multiple cars at once, granted they are different colors.

The image below shows the setup with my “laptop rain cover” consisting of a clear plastic storage bin.

“Going around in circles is a lot more fun when you keep time!”

Test setup using a Carerra Slotcar Track

Originally I considered programming my own lap timer. I researched several Javascript options and stumbled more or less by accident into several slotcar forums and sites. I grew up with a Carrera 140 Servo Slotcar track and just recently acquired a Carerra Go track for some family fun. Turns out the slotcar boys are really into precise timing and “why re-invent the wheel” when a genius like Gregory Braun over at hoslotcarracing.com already build a great piece of software.

In a nutshell the setup uses a standard Photo transistor connected to a Gameport to USB adapter which is plugged into a Windows computer (the pic above is a Intel chipset Macbook Pro booted into XP). A laserpointer is mounted across the track. Every time the vehicle interrupts the laser beam the photo transistor acts like a joystick button is being pressed and the lap timer software interprets this as a lap being completed. Note: my setup here can only support one vehicle on the track. Mount your photo transistor into your track and build a bridge with light source from above for multi car setups. For slotcars you can get away with LED’s as lightsource, however due to the wider wheelbase of 1/10 scale R/C cars and the consequently bigger space between photo transistor and light source I recommend a laser pointer as light source.

Infrared Photo transistor triggered by Laser pointer

The banana jacks on the top are wired to joystick button 3 and 4, allowing for 2 additional photo transistors or any other switch to trigger the timing software. A USB to Gameport converter is housed inside the project enclosure.

——-

Components:

——-
Gameport to USB Adapter – available at Amazon $20

Infrared Phototransistor – available at Radioshack $1.95

Project Housing/Enclosure 6x4x2 – available at Radioshack $4.99

Banana Jack 4x – available at Radioshack $2.99

Flashlight Reflector

————————————-

Internal Wiring

Pin 1-14 are according to a PC Gameport.

The image below was created by HO Slotcar Racing.

Here is a great graphical Pin-out of a PC gameport

————————–

Software

The Lap Timer Software will run on Windows XP and can time up to 4 vehicles at the same time. I have not tested the lap timer using Vista.

Download here.

Credits: Lap Timer Software is created by Gregory Braun at hoslotcarracing.com