PIC RF Transceiver

[Bob Brady]

Can any of you folks recommend a good RF Transceiver for PICs? Or do most of you use a pair of TXLC/RXLC 434s from Rentron?

Thanks in Advance
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This message was ported from CCS's old forum
Original Post ID: 10707

[Bob Brady]

<font face="Courier New" size=-1>I found my answer in the form of an Abacom AM-RTD-315. Also found an excellent RF Comm Primer using CCS compiler and the PIC 16C77 at

<a href="http://www.ottawarobotics.org/articles/rf/rf_article.pdf" TARGET="_blank">http://www.ottawarobotics.org/articles/rf/rf_article.pdf</a>

Manchester coding is explained and sample code given.





:=Can any of you folks recommend a good RF Transceiver for PICs? Or do most of you use a pair of TXLC/RXLC 434s from Rentron?
:=
:=Thanks in Advance</font>
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This message was ported from CCS's old forum
Original Post ID: 10716

[Eric Minbiole]

:=Can any of you folks recommend a good RF Transceiver for PICs? Or do most of you use a pair of TXLC/RXLC 434s from Rentron?

Take a look at <a href="http://www.linxtechnologies.com/ldocs/f_prod.html">Linx Technologies</a>. Their SC series transceivers are reasonably priced ($44 digikey) and are very simple to use: just connect them up to the PIC's uart. I've used them on a couple of projects, and they've worked very well.
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This message was ported from CCS's old forum
Original Post ID: 10721

[Richard Slater]

:=Can any of you folks recommend a good RF Transceiver for PICs? Or do most of you use a pair of TXLC/RXLC 434s from Rentron?
:=
:=Thanks in Advance

How about the Tx/Rx pair from Maplin, code VY48C. (�9.99 for the pair). Maplin has a selection of other modules, but this is the cheapest.

I've never tried them, but may be doing so soon. (so any feedback would be greatfully received!) They sound pretty easy to use, but there is no real data on them, until you buy them!

Richard
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This message was ported from CCS's old forum
Original Post ID: 10737

[R.J.Hamlett]

:=:=Can any of you folks recommend a good RF Transceiver for PICs? Or do most of you use a pair of TXLC/RXLC 434s from Rentron?
:=:=
:=:=Thanks in Advance
:=
:=How about the Tx/Rx pair from Maplin, code VY48C. (�9.99 for the pair). Maplin has a selection of other modules, but this is the cheapest.
:=
:=I've never tried them, but may be doing so soon. (so any feedback would be greatfully received!) They sound pretty easy to use, but there is no real data on them, until you buy them!
:=
Most of these modules are pretty similar. There is a semi 'standard' for the pinouts on several ranges. I have used several ones from about three different manufacturers with the PIC, including versions at 433MHz, and the higher 915MHz version. All are pretty easy, accepting 'logic' serial, at various rates (some are only rated for 1200bps, while some go much higher). There are obvious 'design constraints', such as the need for care to provide good smoothing on the supply, to prevent RF noise from getting back into other parts of the circuit (in general I was using 'loop' antennae formed directly on the PCB, which makes this worse), and (conversely), to prevent noise from the PIC, reducing the sensitivity of the units.
Details of the modules are available from:
<a href="http://www.rfsolutions.co.uk/products/rf_modules/rf_modules.htm" TARGET="_blank">http://www.rfsolutions.co.uk/products/rf_modules/rf_modules.htm</a>
Where datasheets are available, which makes design a lot easier. The more expensive modules give better noise immunity and range.
Generally, you will have to design a self correcting transmission code (it is preferable to reduce the need to retransmit, since the 'turn round' is often quite slow).
I used a small 'packet', that was coded with a 12,8 hamming code, followed by a CRC, and then duplicated with all bits inverted. This gave very reliable transmission, but at the cost of sending an average of 25.5 bits for every byte required (using a 32byte packet).

Best Wishes
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This message was ported from CCS's old forum
Original Post ID: 10740

[Jon Fick]

You wrote
:=I used a small 'packet', that was coded with a 12,8 hamming code, followed by a CRC, and then duplicated with all bits inverted. This gave very reliable transmission, but at the cost of sending an average of 25.5 bits for every byte required (using a 32byte packet).
:=

I once worked on a lighting control system using a 900MHz Linx Tx/Rx pair where the protocol was simplex. (The only feedback mechanism to see if the transmission was successful was a pair of binoculars!) Thus, I needed to ensure that the transmission wasn't stepped on, garbled, etc, and the best way to do that seemed to be to establish some sort of error correcting protocol combined with redundant transmissions. I implemented the Hamming code but quickly found what others already knew... that the Hamming code was really intended for memory bus correction where a single-bit error was conceivable, rather than for the burst errors (several contiguous bits at once) common to RF transmission.

If you get a chance, I'd be interested to know a bit more about your Hamming code and experience, even offline.

Thanks.

Jon Fick
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This message was ported from CCS's old forum
Original Post ID: 10817

[ndineshraj]

Sir could please help the logic of your coding of hamming and crc which would be very useful for me as am struggling too much to get it done........
Please reply as soon as possible.......

it would be very helpful in my life time.............

[rnielsen]

The original post on this thread was way back in 2003. Try finding one that's recent. I think you'll have a better chance at getting a response.

Ronald

[bkamen]

I recently implemented the MRF49XA from Microchip.


It wasn't too bad -- and it's interesting because it has lots of options that you can use or not.

A single chip can operate at either 433MHz or 915MHz (or 868 MHz)

They are $3 in single qty's from Digikey.


So if you're planning on building a LOT of something, these are pretty decent.

There's application libraries to help look at others source -- and the datasheet's not too shabby. (I haven't run into anything that makes me ask, "why is this in the datasheet!?!?" yet...)

Just thought I'd toss that one out here.

-Ben
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Dazed and confused? I don't think so. Just "plain lost" will do. :D