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zig bee for communication between 2 microcontrollers for project

Discussion in 'Electronic Projects Design/Ideas/Reviews' started by chandan28, Feb 26, 2012.

  1. chandan28

    chandan28 New Member

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    i'm working for a project "touch screen controlled robot" in which the direction in which the robot has to move is given by user through touch pad and its a working ....but wired i.e transmitter and receiver part are connected by wire

    i would like to make it wireless.... someone suggested me that using rf tx&rx is one way to do it.... but the problem which i faced using rf (433MHz) is that

    1. it was working properly only when data alone is transmitted(i.e no calculation involved)

    2. but in the program what i wrote requires around 200 ms to generate a state(i.e stop,forward,backward,left & right....... i represented in program by S,F,B,L & R at baud rate of 1200---no problem with baud rate ).... it is generated based on the movement of finger not by arrow mark like keyboard

    3. because of this delay the noise is very high during this interval of 200 ms hence data received will not be correct

    4 since it involves adc conversion and other comparisons i need something which can make it wireless

    i wanted to know can zig bee solve this problem please share your experience of working with zig bee....and how to use it

    if it cannot solve my problem suggest me any other way to do this
     
  2. ronsimpson

    ronsimpson Well-Known Member Most Helpful Member

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    Zig bee and xbee had you digital. There is no analog for you to think about. There are options for error correction and resend of damaged data with out you even knowing it is happening.
     
  3. Nigel Goodwin

    Nigel Goodwin Super Moderator Most Helpful Member

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    Presumably you were trying to send simple RS232 style data over a radio link, this doesn't work properly or reliably for a number of reasons.

    You should either use Manchester coding for the data (don't use hardware UART's) or something like Zigbee modules which take care of that for you.

    I'm currently in the process of setting up nRF24L01 modules, and these are similar ready encoded modules.
     
  4. dave

    Dave New Member

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  5. chandan28

    chandan28 New Member

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    yes i know i'm transmitting digital signal not analog
     
  6. chandan28

    chandan28 New Member

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    i'm transmitting digital signal only not analog signal...and the problem is not with transmission its with noise when no data is sent
    i just wanted to know how does what does zig bee receiver receives when no data is transmitted for particular amount of time i.e can it produce the noise immunity or not
     
  7. ronsimpson

    ronsimpson Well-Known Member Most Helpful Member

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    With a Zigbee there is no "noise" that you can see. There is "no ADC conversion" that you can see.
    There is a RX and TX pins that are like talking RS232. Depending on what mode and what product, there is a packet of data, no noise. When there is no data there is no noise.

    The transmitter sends "I am device 10, I want to talk to device 23, Data=1234656789, end data, check sum.
    The receiver must find the right address, good data, good check sum. then it will send the data out RX.
     
  8. ronsimpson

    ronsimpson Well-Known Member Most Helpful Member

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    A receiver has a automatic gain control. Then there is a strong signal the receiver turns down the gain and thus the noise goes down. Then there is no signal the receiver slowly turns up the gain until it finds a signal or until the noise is very loud.

    If you keep sending something, often enough that the receiver keeps the gain turned down, then you will not have this noise problem. You can send, ..................data......................data.......................and in software remove the ".".
     
  9. chandan28

    chandan28 New Member

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    i think the problem described by me is quite confusing so i've attached the snapshots so that you can get clear picture of my problem

    i've also attached the connection setup it may help you in solving the problem

    In the third picture i dont know what exactly reason behind receiving those characters i thought it may be noise
     
    Last edited: Feb 26, 2012
  10. chandan28

    chandan28 New Member

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    but i could not send data as you told (..................data......................data.......................) my data format or code execution sequence is something like this " process(around 200ms)---data---process(around 200ms)--data " please have a look at the files attached in my previous post that will give clear picture of whats happening actually with me
     

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