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PostPosted: Wed 14. Feb 2018 14:16 
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Location: Sedona, AZ USA
Has anyone developed a lap counting and timing system based on passive RFID tags? Passive RFID tags rely entirely on the reader as their power source. Most passĀ­ive RFID tags cost between seven and 20 cents U.S. each. They can be very small, some not much bigger than a grain of rice. Each car could have its own RFID chip mounted on the chassis. The reader, installed by the finish line, would read the chip as it passed by.

This kind of stuff is beyond my capabilities. Hopefully someone reading this could develop such a system for magracing and perhaps other kinds of model racing. The reader could be portable and used inside or outside.


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PostPosted: Wed 14. Feb 2018 14:51 
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Location: Norway
My hunch is that RFID readers are not fast enough. I'd be happy if I'm wrong.

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PostPosted: Wed 14. Feb 2018 22:14 
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Joined: Tue 7. Oct 2014 22:28
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I have been looking into this and I think you may be correct in that the standard RFID tags may be a little slow, however all RFID tags are not the same and some are regularly are used for runners crossing a line in a race, so may be suitable. Have a look at UHF RFID tags as these may be what you want. Heres some information below about the various types.

https://blog.atlasrfidstore.com/which-rfid-frequency-is-right-for-your-application

One thing with the new design cars is that now they are seek and bind to the transmitter. The Channel ID is no longer constant and hence we cannot use this to flash the IR light under the car. I have deliberately left room under the radio board for a small RFID chip to be used if we can find a suitable one thats cheap. I can incorporate a suitable pocket easily so it clips in if needed.

The new cars also have a fully programmable microcontroller on board and a transceiver (2.4GHz two way radio) so in theory it is possible that the car could calculate its own lap time and then send it back to the base station. Its a bit more involved, but could be an option if we got stuck.

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PostPosted: Thu 15. Feb 2018 15:39 
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Hey.

With a programmable micro controller on board -
in theory we should be able to to program a 'running' signals to switch a IR-led to mimic the frequencies we used to have ?
I'm no circuit wiz but to me that sounds possible. Like taking pw/signal from ch3. ( I know you have applied ghosting at ch3 at the moment ).

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PostPosted: Thu 15. Feb 2018 22:11 
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kiklo wrote:
With a programmable micro controller on board -
in theory we should be able to to program a 'running' signals to switch a IR-led to mimic the frequencies we used to have ?


Yes to flash a IR led would be easy, The only problem is that you would have to input to the microcontroller in the car which frequency to flash at to represent the old channels (1-16) as there are no dip switches. We would need to find a way for the user to input this to the board so the firmware can store it away. Without input switches and leds reporting what you are doing this is a little tricky. But could be done.

Another way would be as follows:-
When bound to a transmitter the car has stored a unique code (I think its a 16 bit number) of the tranmitter ID.
1) a simple switch in the car is triggered when it passes the start line (could be as simple as a reed switch or something). The car starts an internal timer
2) When the car next passes the start line, the car calculates the lap time and begins timing the next lap
3) The car transmits the unique transmitter ID, the the lap number and the lap time (say every 5 seconds or so)
4) A base station recieves the signal and displays it on a screen. Only one base reciever is required as all cars can transmit to it.

With this sort of setup as well as getting lap timing, you are also making other things possible with the same circuitry. For example the base station (or car) could use this data to calculate and simulate tyre wear, mechanical failures and fuel consumption and respond accordingly. The base station would also know how far apart ghost cars are from each other and slow or speed them up so they never run into each other.

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PostPosted: Wed 28. Feb 2018 15:50 
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Location: Sedona, AZ USA
Perhaps the DasMikro Robitronic Compatible Lap Counter System would work.
https://www.banggood.com/DasMikro-Robitronic-Compatible-Lap-Counter-System-USB-Set-p-1093340.html?rmmds=search&cur_warehouse=CN
https://www.banggood.com/Transponder-For-Robitronic-Lap-Counter-System-RC-Car-Parts-p-1009049.html?rmmds=search&cur_warehouse=CN


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PostPosted: Thu 1. Mar 2018 10:02 
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Yes I was looking at this.
The only issues I can see are the cost and also the in car transponder uses 4.2v minimum. This might work, but could brown out.

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PostPosted: Thu 1. Mar 2018 19:03 
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Location: Norway
My thoughts on tapping the onboard micro controller and ch3 was more like this.:

Tap microcontroller for a general frequency then on a ultra small circuit with the necessary resistor etc. get an unique frequency for each car to feed the LED.

To me this sound like a inexpensive and fast way to get going.

I'm awaiting some components in a few weeks i'll try to make some circuit to test. A standalone for a first.

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