I'm building an arduino project (pretty simple, 3 buttons and the keyboard library) but want to add a remote set of buttons as well.
Basically, I'm looking for some help making a very cheap 900Mhz or other free band transmitter to send button presses up to 10 feet indoors. I'm hoping for the remote unit to no have to boot or run any code, just a button press closes a circuit to activate so that it can be battery operated for many months. The receiving side will be a USB powered arduino.
Thanks for any advice!
building a cheap tone/signal radio for a 3 button controller
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- dandenson
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- zener
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- dandenson
- Posts: 52
- Joined: Fri Oct 04, 2013 4:48 pm
Re: building a cheap tone/signal radio for a 3 button contro
That PT2206 looks nice! What's the story on 315Mhz? I that free to use in the US? I need something that doesn't require a license.
Looks like pairing this with the 315Mhz momentary receiver is exactly what I need.
Looks like pairing this with the 315Mhz momentary receiver is exactly what I need.
- zener
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Re: building a cheap tone/signal radio for a 3 button contro
Yeah. A lot of key fobs use this freq. Range isn't too far though. And you can't transmit continuously. I think the license allows only intermittent use.
- dandenson
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Re: building a cheap tone/signal radio for a 3 button contro
I have an application that uses a keyboard and the up and down arrow keys, so I'm only needing 3 different button presses and only for very short duration. Also, average distance is only 5' though a 10' range would be preferable.
Question is, how does this PT2206 identify the button presses uniquely, in other words how do I make sure that a car keyfob doesnt trigger one of the button presses?
Question is, how does this PT2206 identify the button presses uniquely, in other words how do I make sure that a car keyfob doesnt trigger one of the button presses?
- zener
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Re: building a cheap tone/signal radio for a 3 button contro
Well, there are a number of reasons that you would not get false triggers. First of all the range of fobs in general is very short, maybe 20 feet or so. So you need to look at what fobs will be getting that close. Then there is the fact that different transmitters/mfgs use different encoding schemes, and ideally ignore all but pulse trains perfectly matched to their own format. How well this chip does that I have no idea. It isn't to hard to do though. Next this chip has 8 (or more) address pins so you can set it so that your neighbors identical fob doesn't (probably) have the same address. So it comes down to some mathematical calculation of false trigger probability. I have no idea what the answer is. Is it 1 false trigger in a year, in 10 years, 100 years, a month? Don't know. Keep in mind it is $7 so if you need perfect performance then you will have to aim a little higher probably. Maybe someone else has an opinion.
- adafruit_support_mike
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Re: building a cheap tone/signal radio for a 3 button contro
The chip also has 12 tristate address pins. That gives you a bit more than 500,000 unique addresses, which severely limits the chance of a collision.
- dandenson
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- Joined: Fri Oct 04, 2013 4:48 pm
Re: building a cheap tone/signal radio for a 3 button contro
I ordered parts, so well see how it all comes together.
Please be positive and constructive with your questions and comments.