what JTAG to buy.....

Discussion in 'Programmer's Corner' started by Gibson486, Apr 16, 2015.

  1. Gibson486

    Thread Starter Member

    Jul 20, 2012
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    I have a Freesacle ARM board (K22F). I wanted to start doing things through JTAG, but I see lots of them from very cheap (need a paralell port...) to very expensive. How to I navigate and pick one? It looks like Segger is what lots of people use, but once I get past the educational version, the price sky rockets to $600.00.
     
  2. Papabravo

    Expert

    Feb 24, 2006
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    If you can't stand the expense, you don't need to swim in this pond. Is there some reason why tools should be cheap and tool developers should be forced into penury. We thought nothing of dropping $10,000 or more on building our own tools back in the day. Of course our products sold for $5000.00 each.
     
  3. Gibson486

    Thread Starter Member

    Jul 20, 2012
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    So...you are saying that if I want to learn JTAG for my own personal use that I cant unless I spend the $600?
     
  4. Papabravo

    Expert

    Feb 24, 2006
    10,145
    1,791
    No. I'm saying you get what you pay for. If you want a cheap Chinese knock off then by all means buy one and try to get support when it does not work. Or one that installs a virus on your machine.
     
  5. Brownout

    Well-Known Member

    Jan 10, 2012
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    Hi,

    I don't really understand what you're looking for. JTAG is just a standard for a serial protocol used in debugging. It should be very inexpensive, since it was designed to be. Are you looking for a debugger? Or just hardware to use the JTAG port??? FWIW, I wrote my own JTAG software some years ago, for free... very simple. If you could explain a little more about what it is you want to do, MAYBE I can help.
     
  6. MrChips

    Moderator

    Oct 2, 2009
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    Why do you need a JTAG programmer?
    The development board runs straight out of the box. You simply plug it into a USB port and you're ready to roll.
     
  7. Gibson486

    Thread Starter Member

    Jul 20, 2012
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    I wanted to start using a JTAG because sooner or later, it will be our own board. I am not going to simply copy their USB design....I'd imagine it would be better off just implementing JTAG so we can program our own boards. I pretty much got the green light to actually spend money on this, so spending $1k on a JTAG is no issue now.
     
  8. Gibson486

    Thread Starter Member

    Jul 20, 2012
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    I am looking for the actual hardware. There are tons of companies and I am not sure what I actually need. All I know is that we eventually want to use it for our final pcb testing so we can toggle certain pins from a script that controls the JTAG hardware to test our boards.
     
  9. Brownout

    Well-Known Member

    Jan 10, 2012
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    I use a FTDI 4232 mini boad. It plugs into a USB port, and has on onboard Multi Protocol Serial Engine, which includes JTAG. I have not tried to use the JTAG yet, but everything else I've done using this module has been very simple. Also, the MPSE on many microchip PIC's have JTAG, as I believe that would be the case for many other controllers.
     
  10. Brownout

    Well-Known Member

    Jan 10, 2012
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    In addition, you can use just about any $2 uC to bit-bang JTAG interface.
     
  11. Gibson486

    Thread Starter Member

    Jul 20, 2012
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    As much as I would like to do that, I am pretty sure the higher ups would prefer that I just buy the JTAG debugger/programmer. :)
     
  12. Brownout

    Well-Known Member

    Jan 10, 2012
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    It should not cost more than a few bucks.
     
  13. BR-549

    Well-Known Member

    Sep 22, 2013
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  14. Gibson486

    Thread Starter Member

    Jul 20, 2012
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    I see...so that cost is them making their IDE and toolchain. You pay because it works out of the box, where as those cheaper ones is just the hardware that lets you program a board? Could yous till do break points with it? Or is that something that is done in software?
     
  15. Brownout

    Well-Known Member

    Jan 10, 2012
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    Yes. That's why I asked if you're looking for a debugger.

    It might be possible, if you knew how to set up breakpoints. I don't know how that's done, and my hardware doesn't do it natively.
     
  16. vluban

    New Member

    Aug 31, 2015
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    I've made a simple JTAG specifically to play with Freescale Kinetis processors.
    It's fairly slow but it works and it's supported by OpenOCD. But it's Linux only
    as of now, I did not have time to build Windoze binaries of OpenOCD for it, as
    myself I'm only running Linux.

    If you want, you can have one of mines for about $10, I've made more than I need myself...
     
    Last edited: Sep 1, 2015
  17. vluban

    New Member

    Aug 31, 2015
    5
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    With JTAG, breakpoints is a function of JTAG hardware within CPU. JTAG only tells to that hardware address where to stop.

    OpenOCD + GDB provide this functionality, breakpoint in this respect is no different from software breakpoint from the user point of view.
     
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