Simple RF receiver w/ PIC

I am trying to implement something like a little race track for a hand full of tiny race cars (think match box size). For that, I want to transmit digital data (due to the number of cars) from a central point to my 3x3m (9x9 ft.) race track. Every racer will have its own PIC microcontroller, battery and motors.

I would like to use a one way RF connection between the controller (PC) and all the racers. Can anyone give me some links to really easy and really cheap to implement RF receivers with this kind of range?

This is not a commercial product, so 27MHz is a probably good frequency, but not required.

Thanks,

Matt

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Is Infra Red possible (short distance, line of sight). Much cheaper and possible less interference between radio and motor. There are also systems to transmit info over the rails that power your cars. Mostly developed for model trains, but maybe usable for cars as well

Wim

1. No rails. I was thinking about using a striped PCBs as the 'road' and multiple contacts under the car, but that would be too expensive.

1. I though about it, but I am not sure what data rate I could acheive. Also, I may have to shine a video projector into the whole installation (it'll be "art" ya know ;-), which might interfere with the IR (or maybe not? I should test that)

"Wim Ton" schrieb im Newsbeitrag news:cSOfe.6807$ snipped-for-privacy@fe1.news.blueyonder.co.uk...

Ah, oh, cool link. Thanks.

"John - kd5yi" schrieb im Newsbeitrag news: snipped-for-privacy@enews3.newsguy.com...

Elektor magazine published something a long time ago. It used a track divided in many parallel alternating supply tracks (about a car wide). Under the car where 3 contacts in a triangle, with a distance that one of them would always be on a different supply track. A network of diodes kept the polarity constant. I may be able to send a scan if you want. Fitting a battery with enough capacity, motor and all the electronics in a matchbox car sounds a bit tight. Radio receivers tend to be biggish as well.

Use a IR filter to start with. Say that you control speed and direction with 1% resolution.And you will address 64 cars Drivers reaction time is 0.1 sec, so the datarate will be about 200 bit/second. You will have to add some errorcorrection and framing, but you will need less than 1000 bits/sec. Maybe use off-the-shelf RC5 equipment?

Maybe also a subject for the comp.robotics.misc group?

Wim

Yes, that's what I meant. I beleive Maerklin, the model train manufacturer, announced a system like this a long long time ago, but as fast as it popped up, it also vanished again. It would work to get power, but with many cars jumping between strips, I assume I will get lots of shorts and I won't be able to receive any data.

Yeah, I will try that and see how it goes.

I have to address two motors in about 100, maybe even 200 cars. It's somewhat like a swarm experiment for an art piece of a friend (I just do the dirty stuff ;-)

So I figure two bytes per car (car address, motor speeds) per 1/50th of a second gives 200 cars * 50 samples * 20 bits (2 bytes plus start and stop) gives a rate of 200,000bps, or basically that I am out of luck with either RF or IR. Ooopsie.

Wim, thanks for all the help. I will have to sleep over this a few more nights ;-) .

Matt