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JTAG and PIC

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joshh
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2008/05/18 22:52:09 (permalink)
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JTAG and PIC

Hey guys,

Looking through the users guide for the PIC24HJXX, I noticed that the PIC can be operated through its JTAG port. However looking over the microchip site I did not find any JTAG programmers. Am I just blind or is this the case that everything is basically done through the ISP?

Thanks,

Josh
#1

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    joshh
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    RE: JTAG and PIC 2008/05/19 17:49:27 (permalink)
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    Hmm....i'm guessing nobody is using the JTAG port then. I even tried searching around google for JTAG programmers by third parties that work for the PIC. Everything that came up was for AVRs.
    #2
    xiaofan
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    RE: JTAG and PIC 2008/05/19 17:55:03 (permalink)
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    For programming, you do not need a JTAG one as Microchip PICkit 2 works fine as a programmer using ICSP. It only costs you US$35. It supports almost all Flash PIC/dsPIC/PIC32 (and serial EEPROMs and others). The debugging support is also catching up with ICD 2.
    PICkit 2: http://www.microchip.com/pickit2

    But for debugging, I think PICkit 2 (as well as ICD2) is a bit slow for bigger PIC24/dsPIC/PIC32. So I am thinking that Microchip should develop a JTAG programmer/debugger (something like Segger J-Link).
    http://forum.microchip.com/tm.aspx?m=336472

    There are 3rd party JTAG debuggers for PIC32.


     
    post edited by xiaofan - 2008/05/19 17:57:46

      USB_Links and libusb
    #3
    joshh
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    RE: JTAG and PIC 2008/05/19 17:58:50 (permalink)
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    Yeah I plan on adding the ISP connections for ICD2, Pickit2, RealIce, etc.

    However I'm making a development board for people so since the PIC24xx have JTAG ports I wanted to support that. So I was going to try to match my header pinout to some common pic popular jtag programmers but it seems nobody uses them.
    #4
    xiaofan
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    RE: JTAG and PIC 2008/05/19 18:01:05 (permalink)
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    Not so sure if the starter kit for PIC32 is really using JTAG or not as I do not have that board.
    http://forum.microchip.com/tm.aspx?m=33850
    http://forum.microchip.com/tm.aspx?m=295040
     
    3rd party JTAG support for PIC32:
    http://www.microchip.com/stellent/idcplg?IdcService=SS_GET_PAGE&nodeId=2602
     
    I do not know any JTAG support for PIC24/dsPIC33.

      USB_Links and libusb
    #5
    PICkit2Dev
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    RE: JTAG and PIC 2008/05/19 20:53:31 (permalink)
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    This is not an "official" comment, as I don't know much of anything on the topic other than what I've gleaned from datasheets and other specs.
     
    It appears that 16-bit JTAG is a "work in progress" and seems to be in flux.  What support there is is mostly for boundary-scan.  Some devices can be programmed, but they just use a few commands to make a couple JTAG pins act as the ICSP PGC/PGD pins for programming via the ICSP command set - so really it's ICSP anyway.  (See section 24.4.6 of the dsPIC33 family manual).  There is no debug support that I'm aware of.
     
    The latest device datasheets only mention JTAG enough to say "more at a later time."
    Ex: http://ww1.microchip.com/downloads/en/DeviceDoc/70292B.pdf (See section 26.5)
     
    Other than the most recent devices, I don't think JTAG works on many parts:
    Ex: http://ww1.microchip.com/downloads/en/DeviceDoc/80280F.pdf  (see item 16)
     
    or it doesn't use common implementations for programming (ICSP over JTAG pins as noted above), and may change in the future anyway:
    http://ww1.microchip.com/downloads/en/DeviceDoc/80330a.pdf (see item 2)
     
    #6
    joshh
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    RE: JTAG and PIC 2008/05/19 20:57:26 (permalink)
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    Thank you all for the comments.

    Josh
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    jonK
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    RE: JTAG and PIC 2009/02/10 03:22:55 (permalink)
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    I am also looking for some JTAG debugger, but Microchip JTAG seems to be tricky. According to ViaTAP Hardware Manual from http://www.jtagtest.com/docs:

    Problems with Microchip dsPIC and PIC24 devices
    JTAG TDO pin is not electrically fully compatible with other JTAG devices and JTAG daisy
    chaining may not work properly.
    – If the PIC is the only device in the scan chain, the problem is not visible.
    – If all devices in the boundary scan chain must be working properly, the PIC must be the last
    device in the chain (TDO is connected to ViaTAP).

    Also some ERRATA say bad things about JTAG (programming not implemented/etc).
    #8
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