What is meant by DATA0 and DATA1?

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__John
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2012/07/12 06:39:09 (permalink)
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What is meant by DATA0 and DATA1?

I keep reading about DATA0 and DATA1 but nowhare gives the meaning. It seems to be assumned that one knows.
 
What is meant by the terms DATA0 and DATA1?
 
 
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    bytencoder
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    Re:What is meant by DATA0 and DATA1? 2012/07/12 08:55:21 (permalink)
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    You might want to check the USB specs ??
     

    8.4.3 Data Packets
     
    A data packet consists of a PID, a data field containing zero or more bytes of data, and a CRC as shown in
    Figure 8-7.  There are two types of data packets, identified by differing PIDs:  DATA0 and DATA1.  Two
    data packet PIDs are defined to support data toggle synchronization (refer to Section 8.6).

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    newfound
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    Re:What is meant by DATA0 and DATA1? 2012/07/12 09:08:30 (permalink)
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    bytencoder

    You might want to check the USB specs ??


    8.4.3 Data Packets

    A data packet consists of a PID, a data field containing zero or more bytes of data, and a CRC as shown in
    Figure 8-7.  There are two types of data packets, identified by differing PIDs:  DATA0 and DATA1.  Two
    data packet PIDs are defined to support data toggle synchronization (refer to Section 8.6).


     
    Wasn't so hard after all.... [image]app_themes/Classic/image/mIcons/m9.gif[/image]
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    __John
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    Re:What is meant by DATA0 and DATA1? 2012/07/13 01:23:36 (permalink)
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    So, they are types of data packet, identified by different pid's. But I am still non the wiser.
    How do they differ? Why make the distinction? What is the significance of each type?
    Sorry to be a pain wink
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    Antipodean
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    Re:What is meant by DATA0 and DATA1? 2012/07/13 01:31:14 (permalink)
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    __John 
    So, they are types of data packet, identified by different pid's. But I am still non the wiser.
    How do they differ? Why make the distinction? What is the significance of each type?
    Sorry to be a pain wink

    If you want to dig this deep into the 'how it works' then get a copy of Jan Axelsons book 'USB Complete'. You don't need the fourth edition (which is updated for USB3), so you should be able to get a third edition on Amazon for a reasonable price.
     
     

    Do not use my alias in your message body when replying, your message will disappear ...

    Alan
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    bytencoder
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    Re:What is meant by DATA0 and DATA1? 2012/07/13 08:51:47 (permalink)
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    __John
      How do they differ? Why make the distinction? What is the significance of each type?

     
    No difference whatsoever.
    They are just sent alternatively, it is an extra safety-check if there are lost packets, and it is called data toggling (synchronization).
    It is used by all transfer types except isochronous (which uses only DATA0).
     
    Note: you have to handle this on the PIC SIE, via the DTS/DTSEN bits in BDxSTATUS.
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    __John
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    Re:What is meant by DATA0 and DATA1? 2012/07/17 06:43:28 (permalink)
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    Many Thanks!!
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