Simplest Bluetooth/other wireless link possible

[carbonzit]

Another thread here got me to thinking: what if a guy wanted to set up the simplest possible wireless link, one that would only transmit a single bit of information ("I'm here! Wake up!"). How would he do that?

Leafing through the Digikey catalog (and I mean the physical catalog, all 2,896 pages worth) I find a couple of chips that look intriguing. They're made for automotive control, like this one (Atmel's ATA5275), which is actually a small transmitter intended for TPM (tire pressure monitoring--hey, I never heard of that before either!).

It's small, cheap (~$5, qty. 1) and looks to be fairly simple to connect and program. And of course they have corresponding receivers.

So would this work? Are there any even simpler devices out there? I'm thinking about single-chip solutions.

And how hard would it be to do this with a homemade discrete circuit, say a simple RF xmitter/rcvr?

I guess one possible problem would be that this could interfere with your car if it already had TPM capability ...

 

[Sceadwian]

Over what distance under what circumstances? There are a hundred cheap ways to do basic RF, not a single one can be considered until the specific application is considered.

 

[carbonzit]

Over what distance under what circumstances? There are a hundred cheap ways to do basic RF, not a single one can be considered until the specific application is considered.

Other thread was about a guy wanting to do it within a car. Let's say a short distance, <10 ft.

Now, how much information do I have to feed this machine before it starts giving me some results???

 

[Sceadwian]

Within a space of less than 10ft, you generally would NOT use a wireless connection.

There is no other thread, you linked no other refrences. We can't read minds.

 

[carbonzit]

Within a space of less than 10ft, you generally would NOT use a wireless connection.

There is no other thread, you linked no other refrences. We can't read minds.

Humor me, OK? That's what I want to do.

Here's the thread ("Need Help With A Small Project").

 

[Sceadwian]

Look up the technologies that car makers already use for keyless entry. There are very few specifications (security through obfuscation) but it involves a network of sensors both inside and outside of the car to detect an RFID chip that's in the keyfob measure the signal strength to attempt to determine the location of the device (person)

If this is something like what you're looking for, yer not gonna find it for 5 bucks, it's not that simple, why? Learn some basic RF theory you should be able to figure it out yourself. The immediate environment is so critical to an RF sensor (let alone a network) that a distance of a few feet can results in 100% signals reception or none at all and it's not always predictable.

 

[carbonzit]

Look up the technologies that car makers already use for keyless entry. There are very few specifications (security through obfuscation) but it involves a network of sensors both inside and outside of the car to detect an RFID chip that's in the keyfob measure the signal strength to attempt to determine the location of the device (person)

If this is something like what you're looking for, yer not gonna find it for 5 bucks, it's not that simple, why? Learn some basic RF theory you should be able to figure it out yourself. The immediate environment is so critical to an RF sensor (let alone a network) that a distance of a few feet can results in 100% signals reception or none at all and it's not always predictable.

It was becoming evident the more responses I got from you, and now it's crystal-clear: you're not one of the more helpful types here. Demand too much information. Others are quite generous with their advice, but not you, apparently. Thank you for clarifying that.

 

[Dr_Doggy]

ACTUALLY the cat helps alot, even without the straight answers, but hes right, it doesn't sound like you know what you are doing or want to do, switching a "bit" is simple, but you still need to consider what you are switching(relays,ect), encryption, transmission/reception method, so if you want multiple devices, or a sign in your window, you may be taking on too much as a newb, depends on how you want to do it,and wat u kno , ,

you can get a bluetooth TX/RX chip for 10$ somewhere, if you can write to rs232 communications

if you really just want an simple I/O sw just get simple transmitter/receiver circuit

 

[carbonzit]

ACTUALLY the cat helps alot, even without the straight answers, but hes right, it doesn't sound like you know what you are doing or want to do, switching a "bit" is simple, but you still need to consider what you are switching(relays,ect), encryption, transmission/reception method, so if you want multiple devices, or a sign in your window, you may be taking on too much as a newb, depends on how you want to do it,and wat u kno , ,

you can get a bluetooth TX/RX chip for 10$ somewhere, if you can write to rs232 communications

if you really just want an simple I/O sw just get simple transmitter/receiver circuit

I think it was pretty clear what I was asking for, and no, I'm not a clueless newbie here.

By "one bit" what I mean is that the wireless link has to do the simplest thing possible: change state (from what to what doesn't matter; say from low to high). In other words, the receiver is essentially a SPST switch that's turned "on" when it receives the signal. That's it.

So can you now suggest any simple solutions, either single-chip xmitter/rcvrs, or a simple RF implementations of the same? It's not that complicated.

Unless, of course, you want to see RFCs, complete military specs, an executive summary, etc. For crissakes, I'm asking a simple (if speculative) question, OK?

 

[Gobbledok]

I think it's valid to ask details of the application. Just for example, you didn't even state in your OP how far you want to transmit a bit.

It's like me asking "What type of capacitor do I need?"

Then you would have to ask me a lot of questions to give a suitable answer. And if I didn't have a chip on my shoulder I would answer them in the hope of getting a good response.

 

[Dr_Doggy]

OK well if you know what your doing, then you already know all you need a simple Morris code transmitter wit matching receiver, schematics are all over google

 

[ronv]

Google ASK OOK. It's what is used in garage door openers. I think you can find them complete on Ebay or DIY.

 

[carbonzit]

Google ASK OOK. It's what is used in garage door openers. I think you can find them complete on Ebay or DIY.

Finally, a helpful answer! And hey, I learned something today (ASK/OOK = amplitude-shift keyed/on-off-keyed).

See, folks, that wasn't so hard, was it? Take that, Sceadwian! No need for a rigorous definition of the problem. No need for exhaustive specifications. No need to even learn anything much at all about RF! Just someone nice enough to give a useful answer without grilling the hell out of the poser of the question.

So it looks like Micrel's QwikRadio line of chips should work. DigiKey has 'em; they're less than $5 each (for the receivers; the transmitters are even cheaper). Require very few external components.

 

[Gobbledok]

Finally, a helpful answer! And hey, I learned something today (ASK/OOK = amplitude-shift keyed/on-off-keyed).

See, folks, that wasn't so hard, was it? Take that, Sceadwian! No need for a rigorous definition of the problem. No need for exhaustive specifications. No need to even learn anything much at all about RF! Just someone nice enough to give a useful answer without grilling the hell out of the poser of the question.

LOL dude you get grilled for your attitude, not for your non-specific questions.

 

[Sceadwian]

No, of course not... No need for rigorous definition of the problem... It only took 13 posts to satisfy you, and you could have found that if you looked the original question up on Google in the first place, not to mention you probably have at least a half dozen reports about your attitude in response... Even the people here that hate my guts personally, respect my opinion occasionally.

Let me google that for you

OR possibly doing some basic Wikipedia searching first?

 

[carbonzit]

No, of course not... No need for rigorous definition of the problem... It only took 13 posts to satisfy you, and you could have found that if you looked the original question up on Google in the first place, not to mention you probably have at least a half dozen reports about your attitude in response... Even the people here that hate my guts personally, respect my opinion occasionally.

Let me google that for you

OR possibly doing some basic Wikipedia searching first?

Look, you unhelpful twit (I'm being polite here): How in the world could I possibly know to Google something I don't even know exists (like ASK/OOK)? It was only through the kindness of one particular strange that I acquired that information. So far as I know, that's the purpose of this goddamn board in the first place. If we were all able to simply Google our answers, there'd be no possible need for fora such as this. So please, try to look past the end of your particular prejudices and hangups before tweaking others for asking questions in the manner that they do. I could see getting dinged if I committed the same sins that all of those Indian and Pakistani students here do, with their incessant demands for information without a whiff of info on their part. I think I supplied adequate data for the question. At least one other person here, the one who answered me with useful information, seems to agree.

 

[Sceadwian]

You did not supply adequate data. I'll retract that statement when you provide results from the device you create with what you've learned.

Prove me wrong.