How do does the logic analyzer in the Pic Kit 2 work?

Discussion in 'Embedded Systems and Microcontrollers' started by spinnaker, Nov 4, 2012.

  1. spinnaker

    Thread Starter AAC Fanatic!

    Oct 29, 2009
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    I own a Pic Kit 2 and not a 3. I understand there is a logic analyzer in the Pic Kit 2.

    I was watching this video

    http://www.eevblog.com/2009/10/21/eevblog-39-pickit-3-programmerdebugger-review/

    (which is hilarious BTW, especially the response)

    and noticed the 2 does not seem to have any extra wires for the analyzer.

    How does it work then? Is it just the registers that are being read and the pins not actually sampled?
     
  2. JohnInTX

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    Jun 26, 2012
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    It works by reconfiguring the 2 ISCP + 1 Aux lines as logic inputs when the logic tool application is running.

    Details in the Logic Tool User's Guide

    While they say its useful for viewing SPI/I2C I would caution that that is so only when you are certain that the bus is clean as the slow sample rate would leave much unseen.
     
    Last edited: Nov 4, 2012
  3. Markd77

    Senior Member

    Sep 7, 2009
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    It just uses the pins on the PICKIT that would normally be used for data, clock and the spare pin. It's not very high speed, but has come in handy a couple of times.
     
  4. spinnaker

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    Oct 29, 2009
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    I see, so the lines are re-purposed. Thanks guys.

    Does the serial input work the same way?

    I wonder why no one has come up with a hack to add the logic analyzer back to the Pic Kit 3? Or is the boot loader proprietary for the 3? Or could you even get the original firmware to replace it back?
     
  5. JohnInTX

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    Jun 26, 2012
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    Chap 7 in the Debug Express User's Guide describes it. I don't know if its in the standard PK2.

    PK3 is a different animal. I don't know why some of the PK2 features didn't migrate with it.
     
  6. spinnaker

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    Oct 29, 2009
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    Look at the videos I posted above. They explain, especially in the second one. :)
     
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