Zigbee UART connection from MAX232

Discussion in 'The Projects Forum' started by Wavelength, Feb 7, 2010.

  1. Wavelength

    Thread Starter Member

    Mar 2, 2006
    13
    0
    Hello, sorry if this already posted but I can't seem to find it.

    I'm have PIC16F873A connection to a max232 chip and connect it to my PC RS232 port. I am able to read and the data from my hyper terminal the intended data from my PIC just fine :)

    My plan is know to use Zigbee to make the project wireless. I intend to still use the PIC and the max232 on the project and just connect it to the ZIGBEE UART port. I know zigbee have a UART pin for serial communication.

    My question, will there be a need to have a chip which change the voltage level of the serial data coming from my PIC trough the RS232 before I can connect it to the Zigbee? Because from the data sheet I can see that Zigbee have a max input of 3.3V and the voltage level from the max232 would be different or it doesn't matter? I still waiting for my Zigbee module to arrive so I can't play around with it yet .:(

    Anyway thanks in advance :)
     
  2. t06afre

    AAC Fanatic!

    May 11, 2009
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    Hard to say without some more information. Do have a link to the data sheet, or the full type number for your ZIGBEE device
     
  3. alphacat

    Active Member

    Jun 6, 2009
    186
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    Hey.

    I'm basically doing what you describe.

    I have an Uc which receives messages from PC through its RX and TX pins, and these messages are transmitted wirelessly using ZigBee protocol.

    I'd love to help you but as was said here, more details are needed.
    You can send me a PM with your msn account and we can discuss it :)

    See ya.
     
  4. t06afre

    AAC Fanatic!

    May 11, 2009
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    I think all people visiting this forum should be able use the result from your discussion. So please continue the discussing in the forum. No need to go private in this case.
     
  5. Wavelength

    Thread Starter Member

    Mar 2, 2006
    13
    0
    Thanks for the reply :)

    The Xbee is a 20 pin with chip antenna which is from Digi.I'm not sure about the chip manufacturer but from the PDF it seem its from Ember. Anyway it was actually included in BL4S100 SBC from Rabbit Controller. I was thinking to just take the Xbee module and implement it for this wireless idea. :)

    I attached a PDF about the Xbee module.

    R201WW0721575
    XB24-Z7CIT-IO59-revB
    2008-12-11-19
     
  6. t06afre

    AAC Fanatic!

    May 11, 2009
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    From page 14 in the data sheet, I would say that a MAX232 is not needed if you want to connect the ZIGBEE to the PIC. But I guess both have to use 3.3 volt as supply voltage on the PIC
     
  7. John Luciani

    Active Member

    Apr 3, 2007
    477
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    The XBee is RS232 at 3.3V TTL levels. If you have to run your uC at 5V
    then either a resistor divider or an AHC buffer will work (AHC has 5V tolerant
    inputs).

    IIRC the XBee series two is Ember radios. I believe the Series I is Freescale
    radios. Also I do not believe Series I and Series II can be mixed.

    If you are doing a very low power system that will put the XBee in sleep mode for
    long periods of time you may want to consider running the XBee at 3V. The current
    in some of the sleep modes is dramatically reduced. I did a little Zigbee writeup with an XBee power example. See http://wiblocks.luciani.org/white-papers/intro-to-zigbee.html

    If you decide to use an Atmel uC checkout my board that integrates an ATmege328
    with an XBee on a single PCB. http://tinyurl.com/5rfmrz

    (* jcl *)
     
  8. t06afre

    AAC Fanatic!

    May 11, 2009
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    Using a 5 volt tolerant buffer is a good idea. You have 3 types in the 7400 series that can do that.
    75LCX - CMOS with 3V supply and 5V tolerant inputs
    74LVC - Low voltage - 1.65 to 3.3V and 5V tolerant inputs, tpd<5.5nS@3.3V, tpd<
    74LVX - Low voltage - 3.3V with 5V tolerant inputs
     
  9. Wavelength

    Thread Starter Member

    Mar 2, 2006
    13
    0
    Thanks for the input. Sorry guys for the late reply went for an outing yesterday. :D

    So I can just supply my pic and the max232 with 3V supply voltage and the output will be compatible for the ZigBee 3.3v TTL input ? Guess so since the PIC and the RS232 output is reference to the supply voltage please correct me if I'm wrong. Looking from the PIC data sheet it can work using 3v supply but the max232 need 5v for minimum supply.

    Anyway I don't want to change the supply voltage and removing the max232 for the mean time.Maybe later on I can swap the 5v regulator for a 3v regulator and make another circuit.:)

    So now I'm going to use resistor divider or an AHC buffer solution. But I guess I will try with the 5 volt tolerant buffer first. I will post the update on how its goes hopefully I will get the development kit for the Xbee this week . Thanks to t06afre and John Luciani :)
    sheet

    I attached the PIC data sheet I'm using the 28pin PIC16F873A.
     
  10. Shanemaneman

    New Member

    Feb 15, 2012
    2
    0
    hi,

    I have placed some news and PR relevant to different wireless short-range-protocols in http://www.short-range-wireless.com and I hope to be able to learn from your views and ideas in order to allow the different blog users to get an up-to-date overview and availabilities for the different technologies Feel free to traverse both the technical and business sections to find valuable documentation regarding short range wireless networking technology
     
  11. mypearl

    New Member

    Feb 7, 2012
    10
    0
    test post, i cant post a new thread
     
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