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General project discussion / help
Did you make a robotic coffee pot which implements HTCPCP and decafs unauthorized users? Show it off here!
I'm thinking of building an experience which allows a user to learn more about a physical object by pressing an adjacent button. Upon press, a TV will play a video describing the piece in more detail. Think of a large wall of posters (each with their own button) with a shared screen in the middle. These posters must be quickly interchangeable so a wireless solution is a must. Also, the transmitting device should run off a battery and be inexpensive.

I've used Bluetooth LE in the past and am confident I can easily use something like or to accomplish my task. But at ~ $30 a pop, that's getting to be an expensive project.

I think I'd like to try RF transmitters and receivers (, but I'm not sure if they're the right fit for my project. In the given examples for each product, it looks like both the transmitter and receiver require a micro controller. Is it possible to use the transmitter without a controller and still produce a unique signal for a receiver?

Thoughts? Any other approaches?
joelongstreet wrote:Is it possible to use the transmitter without a controller and still produce a unique signal for a receiver?
I think you're on the cheapest cost RF approach, but no I don't see any good way to use these simple AM Tx/Rx pairs w/o some form of "controller". You may want to look at Adafruit's 4 "key" fob Tx/Rx set. IIRC there isn't a micro-controller in them but rather a encoder/decoder set (PT 2262/2272) that could do a lot more than just 4 unique IDs. But you'd have to hack their PCBs or come up with one of your own. I'm not sure that's any easier (though likely less $$s) than using something like a Trinket connected to the Tx end to send a unique message/ID. Something more robust would be connected to the Rx end to run your video on demand.

Then perhaps there's something in the acoustic/ultrasonic line that could work for less $$s. Perhaps a form of DTMF ?

But tell me why "quickly inter-changable" precludes some really simple wired idea ? How many panels are they to be ? Spaced over what range of distances from the main video display ? For instance, why not use RJ45 jacks and plugs and wiring ? Why not a wired connection that gets made via whatever physical connection there is ... the one that's holds the "poster" to it's wall ?
The RN42 is about $15 each and easy to use, but I don't know its power consumption.

You could use those transmit/receive modules with multiple transmitters, each being modulated at a different audio frequency, maybe with a 555 or something like that. The receiver would then only need to measure the pulse frequency to determine which transmitter was sending. That's a pretty cheap option as long as you don't care about problems if multiple buttons are pushed at once.