Sending/receiving data from multiple units

Hey guys,

I have a short question concerning a new project I am just starting. So my friends and I are planning to build a race course for RC cars and each one should have a radio transmitter (or something similar) which is then sending information (like how fast it is going and its position) to a computer. I tried to think of a method to realize this but came up empty and my google search came up empty - which is probably due to lack of a fancy description of the search terms... - is there some kind of wireless signal transmitter/receiver you could think of? It should handle multiple inputs to one receiver and each one would need an ID and some other parameters basically...

Thanks so much for your help!

GPS tracker ?
http://www.pronto.com/user/search.do?SEM=true&query=arduino+gps+tracker&adid=b99960b9-a6ad-43a8-8da0-6b16b8c4d229-0-pt_msb&kwid=arduino%20gsm%20gps%20shield&cid=2858595103&loadingComplete=true&owl=true

GSM/GPS ?

This GPS/GPRS/GSM shield uses an embedded SIM908 chip from SIMCom.Featuring an industry-standard interface and GPS function, the combination of both technologies allows goods, vehicles and people to be tracked seamlessly at any location and anytime with signal coverage.

lefthand3r:
each one should have a radio transmitter (or something similar) which is then sending information (like how fast it is going and its position) to a computer.

I have done something a little similar with radio control for model trains using these devices. One of them is connected to my PC by USB connection and it transmits and receives commands/data from the locomotives.

...R

Google up OOK (on-off keying) radios. I am using them to report sensor readings back to a main base station. Plenty of them available on EBay. The transmitters transmit when you pull one of their inputs high: they just transmit a sine wave. Likewise, when the receiver senses a signal at the right frequency, it sets an output pin high. Also, they're very small and cheap.

But you are responsible entirely for your own communications protocol and modulation format. In my case, I have each sensor send a series of pulses, each of a length representing the data carried (sensor ID, message type, etc.) , separated by 30 ms. low. I also use a 30 ms. leadin pulse to wake up the receiver, and I use a check pulse at the end, which is a sum of some of the data sent. That is very valuable for rejecting bogus receipts. For a detection scheme, I just run a 2Khz clock, and keep looking for 30 ms. continuous high on the chosen input pin. When I find it, I keep track of the intervals for which the input pin is high and low, and derive my data from that.

One difficulty you might have would be to assure that you don't have the transmissions overlapping. If you had some sort of clocks in your race cars, you could probably schedule transmissions to not overlap.

Good luck

John Doner

@Robin2,
Are there any example tutorials for the Deltino ?

EasyTransfer makes this simple. Or simpleish.

You'd need to build a packet format, something like:

struct SEND_DATA_STRUCTURE{
  byte car_id;
  unsigned int speed;
  byte amps;
};

To prevent everyone talking at once, have the computer send a request for data by setting the car_id to the appropriate car_id, then wait a specific amount of time for the car to respond. Repeat ad nauseum.

Google "HM-TRP Telemetry" for a radio option. You can get them in pairs, one piece with a USB interface, so the computer side doesn't even need an arduino if you're prepared to write a program that will format the packets in the same manner as the EasyTransfer library (which is not hard to figure out). They are capable of transmitting around a mile line-of-sight.

raschemmel:
Are there any example tutorials for the Deltino ?

I wrote this Thread when I figured them out.

The current models have an updated h-bridge that requires slightly different programming to keep the smoke in. I can explain if you get that far.

...R

Thanks so much guys,

I will try to read on all of the suggested ideas and get back to you if I figured out what to use :slight_smile: :slight_smile: :slight_smile: