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Best cheap wireless communication? Answered

Device x has a button and is 25 feet from device Y. Device Y needs to know when the button is pressed and activate device Z, but it has to be cheap and if I have a lot (A LOT) of these sets near eachother they still need to work without interfering with eachother. Best Solution?


How much power can it consume?
how physically robust must it be?
how much bandwidth? (how often are you turning one/some/many/all of them on or off)?

There are radios like the xbee with short-range mesh networking to microcontrollers; each being assigned an address and any node capable of sending or receiving. They aren't the cheapest but they are inexpensive in quantity/lower end models with lower power. *(under $10 each in quantity according to a forum post I found)

Depending on what you're connecting these to and what cheap means to you, a radio mesh network will get the signals where they need to go.

the question that really answers this question...

WHAT exactly are we making, in what environment, and what design constraints apply? :)

This could be anything from laser-tag to mesh robots.

Truth is I don't know what we're making, it's a research challenge that was issued to me by a mentor.

Cheap means cheap, as in Xbee is certainly too expensive. IR is of course going to be the cheapest solution, but I don't know if line of sight is something that this system would have.

...remembering IR is virtually useless outdoor/in sunlight...

It's unfortunate because a mesh network of even the cheapest wireless I can think of is at least $10/node...

I wouldn't use individual wireless transmission with "A LOT" of devices, when the range is that short. You'll run out of bandwidth in the FCC-allowed frequency ranges, if you space them far enough apart to avoid interference.

You could pull twisted pair (or even just a single wire) for each X-Y pair, but that gets unpleasant (bulky cable or really wide ribbon) with "A LOT" of devices. You could pull optical fiber and put a multiplex/demultiplex transceiver at each end (like HP's GLink), but that is quite pricey.

What about a single frequency receiver with a multipin output (you can get 50-, 100- even 200+ pin connectors), with software to decode a transmitted address and put a signal onto the correct pin? Your transmitters would send their address digitally to the receiver, all on the same frequency.

It MUST be wireless, and each set of devices is not going to be necessarily connected with the others so one giant radio communication line is out of the question sadly. I was thinking IR might work, but I want to see what else I can figure out first.

IR will probably be your best bet so long as you have line of site between transmitter and receiver. Then each device can be looking for a specific code. You could have a single transmitter with multiple buttons and cover multiple devices.