[dorkbotpdx-blabber] Does benito5 only program but not debug AVRs

[Dan Strother]

It's possible to build a clone of Atmel's JTAG ICE:
http://www.scienceprog.com/build-your-own-avr-jtagice-clone/ (or buy,
for a rather lot less than Atmel charges:
http://www.sparkfun.com/commerce/categories.php?c=7 ). These still
rely on Atmel's firmware, though (which won't work on hardware that
doesn't look very similar to a JTAG ICE). You're not tied into AVR
Studio, at least - you can use GDB with the JTAG ICE:
http://avarice.sourceforge.net/ .

Unfortunately, so far as I can tell, no one has successfully built a
clone of the JTAG ICE mkII; so, if you really want to use debugWire,
you may have to fork over the $300 for the mkII...


Dan S.



On Sun, Jun 29, 2008 at 12:41 PM, Paul Stoffregen <paul at pjrc.com> wrote:
> All my debug stuff is for the NXP/Philips LPC2000 chips, which are based on
> an ARM7 (32 bit) core.  I am using the AT90USB82 chip as a USB to JTAG
> adaptor, but I can only debug 32 bit ARM chips, not Atmel's 8 bit AVR chips.
>
> For an analogy, consider using a USB-serial adaptor with an FTDI chip to
> program a bare-bones Arduino.  The adaptor uses a FTDI chip, but it only
> programs the AVR (Arduino) chip, not a FTDI chip.
>
> Most AVR chips have debug wire, which is a closed, proprietary protocol.
>  Some also have JTAG.  While JTAG itself is an open spec, JTAG itself only
> tells you how to access registers inside the chip.  To actually use JTAG,
> additional specs are necessary to know what registers are available and how
> to use them (it's usually quite complicated).  Atmel has published boundary
> scan info for some chips (which allows manipulating the external pins for
> testing the circuit board traces), to the best of my knowledge, Atmel has
> never released  JTAG debug register specs which would be necessary to use
> that JTAG port to debug an AVR processor.
>
> If those JTAG register specs are available for AVR chips, please tell me
> where.
>
> Without that info, there is no hope of ever making an open debug tool for
> the AVR/Arduino (which is the main reason I'm using the ARM chip).
>
>
> -Paul
>
>
>> Paul Stoffregon has done some work towards this using the at90usb82. Debug
>> wire as I understand it is Atmel proprietary.
>
>
>
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