Hi,
I have finished the design and test of the Personal Lap Timer.
Its a very simple project that involves an Arduino, LCD, Infrared decoder, a few buttons, a peizo buzzer and not much else.
As I can't decide on the best way to publish the design or whether the published design should be based on an UNO or a stripboard Arduino I came up with the idea of a 'build along' where as a group we can build a few designs simultaneously.
If anyone is interested in following along/joining in with this approach, please post a reply here.
Its a lap timer for use with any type of vehicle from RC Cars to Go Karts to Race Cars.
How does it work ?
It uses a low cost infra red transponder which can be mounted in the car for RC Cars or on the track for Karts and Race cars, an Arduino then calculates, displays and records lap times. The device can be built small enough to mount to the steering wheel of a race kart.
Infra red, that wont work will it ?
Infra red has been used for years to provide track side timing at race tracks. There are commercial solutions for around 150 dollars that use this signal to provide in car timing, the personal lap timer has comparable features and can be built for about 40/50 dollars including the transponder.
What does it look like ?
Arduino Uno Version -
Standalone Arduino Version -
How can you get one ?
Show your interest here and follow the build along.
Hi DuaneB,
I'm with you on this build. I've just built my own lap timer for karting using the very same IR Beam method (I can add some build photo's if interested?). I'm getting close to the test stage now once i've sorted the battery life. I want to use this to time a 24hr karting race with the timer on the steering heel. I've added an SD card to record the lap times as the on board Arduino memory isn't enough, but this gives another advantage as it can be downloaded to a PC very easily for later analysis. I've also built a custom IR transmitter to go on the pit wall based on the AIM system but with a different transmission code to avoid picking up someone else's genuine beacon at the track.
Maybe we can share some learning and hopefully improve both our designs?
ok, so some images of my build. No buttons as all the variables are read from text files on the SD card as I want to eventuall make this water proof as the weather in the UK is un predictable.
Early screen shot
Box with final graphics
Stripboard Arduino with sd card module
Sensor on fly lead so can be positioned any where on the Kart
Things left to do: Sort out battery power (May use 3 14500 3.7v AA size rechargeables?). Work out fixing method to steering wheel. Test on track. Make waterproof so can be used through the glorious British summer.
Hi,
I am using the EEPROM as I wanted to keep the costs down, but SD Card is definitely the way to go, its also a nice idea to store the parameters on the SD, its much easier and less tedious than writing menu code.
I notice that jimEli is testing for specific beacons, is there a database of beacon signals anywhere ? if not and you know the signals that a particular beacon type uses, how about posting them in this thread ?
As far as I can tell, the work jimEli has done on his blog to read the AIM beacon code is the only thing I could find anywhere about what codes are being used by each manufacturer. I used his idea to read three complete code sequencies to ensure the correct beacon was read.
I'll keep looking to see what I can find and if anything is available i'll post it here.
I the built my own beacon using another stripboard arduino and programmed it to my own code with a range of about 30 -35 meters.
As a second fail safe, once the timer receives the IR code it does all of its processing (calculating lap time, recording to sd etc) then switches the IR receiver off for a pre determined length of time (variable text file on the sd card which is slightly less than the best possible lap time). It then switches back on just before you pass the beam again to read your next lap - no need for interupts.
I have been busy with other projects, mainly this Arduino yaw control system for RC Car -
I have done some work on the lap timer today with a view to finally getting the code to a publishable state. Will take it to the track tommorrow and if all goes well I will finaly publish the project. I don't think its radically different from any of the others, other than that its mine
I have completed part one of the build along today. Its breadboard based, step by step and I hope easy to follow.
The end result is the basic lap timer without beacon detection. Part one gets you to the point of having working multi session, multi lap stop watch with session averages. You can review previously recorded sessions and laps as they are recorded in the Arduino EEPROM.
Total cost of parts in addition to an Arduino is around 15 dollars.
Part One is here -
Part Two will introduce automatic Infra Red lap detection using the types of beacons commonly found at Kart and Auto race tracks
Part Three will cover building a simple beacon for about five dollars.
I was searching for something like this! I will follow your steps to finish the part one right now, I hope you publish the second and third part as soon as possible!
Glad you like, I have just rebuild the circuit following the instructions - I posted the LCD to Arduino pin connections in the reverse order, I will updated the blog and let you know in this thread when I have corrected.
We do not have a timing system at the new RC Track in Dubai, so my lap timer is the only opportunity anyone has to time their cars.
Its been a real mission to design a transponder that will work reliably in an RC Car with an old brushed racing motor and an ESC that is glitchy at the best of times however I now have a proven system which does not interfere with the car and is also not effect by noise originating from the car. It is finally a really good system that I can just forget about the design and just really enjoy using.
The next part of the build along is up on the blog, its primarily the parts list for building the transponder, next week I hope to get some video of the breadboard version being used at the track and the the final few steps of the build.
Hi,
I have had a busy weekend, after managing to squeeze ten servos out of two Arduino pins,
I ran an informal RC Car competition at our local track in Dubai using the Arduino based lap timer system featured in the build along.
Here is a video of some early laps with two of the lap timers, one using a standalone Arduino and the other one is the actual lap timer from the blog, all I have done is taped it to a board and taken it to the track -
It was a lot more fun that I expected, the video is from earlier in the day, but after everyone had had at least on go at setting a time, people would crowd around the lap timer to watch the times coming in and make sure theirs was not getting beaten. People calling out your times as you get closer to the lap record really puts the pressure and makes the cars so much more fun to drive.
Everyone at the club wants another go on Monday - its 47 degrees outside and people are queueing up to get back out in the heat and try this system again. Overall I knew I wanted a lap timer to race against myself on whatever temporary track I put together, but this has been a lot more successful than I expected at the club.
As per previous posts this is for Karting rather than RC cars so its the other way round in terms of the IR stays at the side of the track and the screen and timer go on the steering wheel.
Hi,
It certainly looks securely fixed to the wheel ! What is it, a Sodikart ?
Have you tried using 555 Timers to generate the transponder signal, they can drive a lot more power than an Arduino pin giving you greater range at much lower cost.
The ones I put in the RC Cars are 11 grams, they output about 100mA so nice strong signal if you wanted to use them on the pit wall.
I thought I had posted a stepy by step build of the transponder - but clearly haven't ! I will write this up over the coming days - I remember taking all the pics for it.
Hi DuaneB,
This kart was a Pro Kart but it could equally fit a Sodi kart without any mods.
I orriginally used a 556 timer chip for the transmitter but because some other karts on track were using a commercially available systems I didn't want my timer to be triggered by there signal so I transmit a repeating code (like a TV remote) rather than a continous 38khz IR stream (this is how the commercially available systems work as well, I just chose an unused code). That's why I swapped to the Arduino for the transmitter as it was easy to reprogram to get an unused code. The power I needed for the LED's is about 500mA when on so both the Arduino and a 555 / 556 chip couldn't sink this much current so I used a BD237 2A transister to sink the current for me. With this power I can acheive about 35m distance from the pit wall and because the led duty cycle is about 7% its overall power consumption is about 40mA.
This is the transmission code I'm using
And this is the device schematic using the transitter to sink the current (Power connections are simplified here)
Using a code could be useful on RC cars too as you could run each car with a different 'code' and use one receiver to time them. If you placed the receiver above the track then other cars wouldn't block the signal.
I may also be visiting Dubai later in the year as there is a 24 hour kart race at the Motor City Kart track in December. We are currently trying to find a sponsor which we need to help with the funding.
