AUREL TRX 868 FSK transceiver usage

Discussion in 'Wireless & RF Design' started by flotul, Aug 3, 2016.

  1. flotul

    Thread Starter New Member

    Aug 3, 2016
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  2. jpanhalt

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    Jan 18, 2008
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    I presume you mean the RTX 868 and have not used it specifically, but your attached description suggests it is similar in purpose to the ZigBee pairs with which I do have experience. It uses a "proprietary", Manchester-like coding, and communicates at 9600 baud. While that baud rate is common, it is quite slow compared to ZigBee and other similar devices.

    That said, there is not much help we can provide with a "don't work" description of the problem. Please show how you have hooked it up and details, including your code, of how you are communicating with it.

    John
     
  3. flotul

    Thread Starter New Member

    Aug 3, 2016
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    Hi John,

    By "I can't get them to work" I meant I can't make one module sending data to the other one.

    What I did up to now is to setup the modules in simplex comm, one as TX and the other one as RX and transmitted low speed serial data (1200-2400bps) for tests.

    On the TX one, I have connected a FTDI USB/Serial cable and send data. ON the RX module, I've connected my scope watching for any signal on the RX pin.

    But up to now, I see nothing "transmitting".

    I must miss something, but what. I triple checked the cabling, changed breadboards, got two cups of coffee but no better result up to now.

    Is there any way to check things step-by-step and, for example, make sure the TX is really sending something?

    A few days ago, I found somewhere on the web a guy saying that these modules are "so transparent" that one can use them as morse transmitters since he apparently connected a button on the TX side sending +0,6V or 0V signals and a scope on the RX side. Weird... Can this be true?

    Roger
     
  4. jpanhalt

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    Based on my experience with ZigBee, I can agree that such modules can be"transparent" and have no reason to doubt the person's comment in your last paragraph.

    If by that, you mean you got your two devices communicating to one another via a wire before you tried the wireless, that is exactly what I did. If not, then I would suggest doing it. These devices are sold as "replacing wires," and I effectively took that literally.

    As for using an FTDI cable, can you see your serial signal on the output of the cable? If yes, when you connect that to the transmitter module, can you still see the signal at the input pin of the TX module?

    John
     
  5. flotul

    Thread Starter New Member

    Aug 3, 2016
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    Yes, I first built up a "wired" circuit, tested and because it was okay, I replaced the wires by the modules.

    By "simplex" I mean I send data only from A to B, never from B to A.

    And "yes", I can clearly see data going out (and in if needed) from my FTDI cable.

    I don't think there is a cabling or data problem. My feeling is more around the modules themselves...but what is it?

    Roger
     
  6. jpanhalt

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    Unfortunately, a module specific problem will best be addressed by someone who has used that exact module. For example, the ZigBee modules I had needed to be set up to talk to each other using a PC. It was very simple to do, but necessary in that case.

    Do your modules go through a handshake and acknowledgement when you turn them on? ZigBee's do and you get a green indicator LED. If you have an indication they are talking to each other, then I am out of suggestions. If there is no indication, is there a test you can run to be sure they recognize each other?

    Sorry that I cannot help more.

    John
     
  7. flotul

    Thread Starter New Member

    Aug 3, 2016
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    Okay,

    I've just received two new modules and guess what, it works now.

    I think, I've made so many different tests that I must have fried one of my first modules, the "receiver" one.

    Stupidly, I didn't think about swapping both modules because I would have then noticed that a lot of garbage comes in even if the transmitter doesn't send anything.

    Thanks again for all your ideas ;-)

    Roger
     
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  8. jpanhalt

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    That is good to hear.

    I particularly appreciate you coming back and giving the update/solution.

    John
     
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