low cost / low part / slow speed contactless communication

Go To Last Post
19 posts / 0 new
Author
Message
#1
  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

Hi,

I'm looking for a REALLY simple contactless method of providing a serial data stream between a sealed 'AVR' and external controller. I'm thinking in the 300-1200 baud type speeds. Needs to be < US$15 for the receiver components.

Options I've seen so far, FM receiver SIP unit - quite bulky, Nordic 2.4Ghz probably more complex than I need.

Any other leads / suggestions or an induction based solution?

Thanks,

Carl

  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

how low is low speed? You can use an inductive loop. Or even an LED. They are both about the cheapest solutions I can come up with.

Writing code is like having sex.... make one little mistake, and you're supporting it for life.

  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

hi,

work on 300 bps for the moment. Any examples of inductive loop scematics / designs that you can point me at?

Thanks,

Carl

LED - probably not feasable on this occasion

  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

zkvii wrote:
Hi,

I'm looking for a REALLY simple contactless method of providing a serial data stream between a sealed 'AVR' and external controller. I'm thinking in the 300-1200 baud type speeds. Needs to be < US$15 for the receiver components.

Options I've seen so far, FM receiver SIP unit - quite bulky, Nordic 2.4Ghz probably more complex than I need.

Any other leads / suggestions or an induction based solution?

Thanks,

Carl


must it be RF-based?
A $3 IR receiver + a cheap IR diode and LOTS of code will do it.

  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

Maybe look at the stuff for RFID - they use inductive loops at around 150khz.

  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

Does the sealed unit have a good power supply? I think an inductively coupled system could be put together, but I'd guess that the current draw would be more than that of the $5 433 MHz RF Tx and Rx units.

Additionally, how big of a surface area do you have for your coil? 6" diameter coil reasonable, or looking for small size?

Also, what is the gap between the two coils, mm/cm/meters?

Can your physical design allow them to be parallel to each other, sharing the same central axis?

Unidirectional or bi-directional communications?

Significant RF or magnetic interference in the environment?

Just some thoughts...

JC

  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

Try Dick Cappels site.
http://www.cappels.org/dproj/minmassrf/Min_Mass_Wireless_Coupler.html
There are other examples also.

Rick

  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

What is the shielding/sealing material that encloses the AVR? What are the RF properties? Will the signal be able to get out? What if a bright eyed, bushy tailed young marketing exec suddenly decided that a metallic housing would look cool? I say go with IR if you can.

If you think education is expensive, try ignorance.

  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

I have on my list of things to try (right next to the toybox of cool chip samples) to try to use Hall effect sensors & electromagnets to try to communicate through plastic (or similar) housings. Haven't gotten there yet. ;)

You can put lipstick on a pig, but it is still a pig.

I've never met a pig I didn't like, as long as you have some salt and pepper.

  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

I suggest you to use a pair of zigBee modules, for example from maxstream. You can use it in a simple transparent mode like a serial line.

  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

try Linx devices.

www.linx.com

Jim

I would rather attempt something great and fail, than attempt nothing and succeed - Fortune Cookie

 

"The critical shortage here is not stuff, but time." - Johan Ekdahl

 

"Step N is required before you can do step N+1!" - ka7ehk

 

"If you want a career with a known path - become an undertaker. Dead people don't sue!" - Kartman

"Why is there a "Highway to Hell" and only a "Stairway to Heaven"? A prediction of the expected traffic load?"  - Lee "theusch"

 

Speak sweetly. It makes your words easier to digest when at a later date you have to eat them ;-)  - Source Unknown

Please Read: Code-of-Conduct

Atmel Studio6.2/AS7, DipTrace, Quartus, MPLAB, RSLogix user

  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

IrDA may be worth considering.

  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

zkvii wrote:
Hi,

I'm looking for a REALLY simple contactless method of providing a serial data stream between a sealed 'AVR' and external controller. I'm thinking in the 300-1200 baud type speeds. Needs to be < US$15 for the receiver components.

Options I've seen so far, FM receiver SIP unit - quite bulky, Nordic 2.4Ghz probably more complex than I need.

Any other leads / suggestions or an induction based solution?

Thanks,

Carl

rfm12 - spi tranceicer
http://www.mikrocontroller.net/t...

/bingo

  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

carrier pigeons

  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

Smoke signals?

Sorry, couldn't resist...

Guillem.
"Common sense is the least common of the senses" Anonymous.

  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

Please. Let's be futuristic. Telepathy.

If you think education is expensive, try ignorance.

  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

Quote:

carrier pigeons

Quote:

Smoke signals?

Now, exactly HOW are you going to get those to/from a sealed AVR?

[Well, I suppose you COULD release the magic smoke--but only once.]

Lee

You can put lipstick on a pig, but it is still a pig.

I've never met a pig I didn't like, as long as you have some salt and pepper.

  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

Solenoid activated by the AVR timer system to open a pigeon cage. The only problem with this system is the high timing jitter and multipathing.

  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

Hi guys,

Thanks for the pointers - the rfm, lynx and Dick Cappels method are all possibles - lots more research needed.

With regard to other options:
telepathy, only seems to work when it is other peoples interface problems
smoke signals - we have fire bans on here, so I don't think that will be allowed
pigeons - I've already got the TX bit sorted, it is really the RX bit and feeding requirements would reduce the running effeciencies somewhat

Cheers,

Carl