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January 26, 2006, 1:54 pm

My JTAG Cable1 has just failed and I need to get another JTAG programmer,
ideally with a USB interface although if it has to be serial so be it.
Obviously I'd get an Atmel JTAG ICE Mk11 if the cost wasn't so ridiculously
high so it'll have to be an alternative.
What are people's views on the best one available at the moment?
Thanks.
Roger.

Re: AVR JTAG programmer choice

I bought the Olimex USB JTAG. It is really a serial JTAG with a
USB-serial adapter inside it, of course. It is cheap, it works exactly
like a regular JTAG-ICE (mk.1), I can't fault it. However you should
note that the documentation is not exactly right, and there are some
things I don't completely understand:
* adapter is target-powered despite being described as "USB-powered".
* you MUST have Vref connected on the JTAG interface, and it must be
connected to some nonzero voltage on your target.

Re: AVR JTAG programmer choice

our AVR-USB-JTAG have opto-isolatation between USB and target, this is
why you have to feed power from target too :)
the good news is that this way you can debug safely targets which are
running on 220VAC
Best regards
Tsvetan
---
PCB prototypes for $26 at http://run.to/pcb (http://www.olimex.com/pcb )
PCB any volume assembly (http://www.olimex.com/pcb/protoa.html )
PCB prototypes for $26 at http://run.to/pcb (http://www.olimex.com/pcb )
PCB any volume assembly (http://www.olimex.com/pcb/protoa.html )
We've slightly trimmed the long signature. Click to see the full one.

Re: AVR JTAG programmer choice

If you are going to use DebugWire (standard on all newer chips with low
pincount), the MKII is your only choice. Plus it handles USB at full speed
natively (Philips USB controller connected to one of the two Mega128)
without having to go through a serial bottleneck.
So it has it's price, but it's worth it. At least for me.
Mit freundlichen Grüßen
Frank-Christian Krügel

OT AVR Flash
How reliable are the AVR's flash?
I have two Atmega169 (in AVR butterfly) failing.
They are supposed to last 10,000 cycles.
And yet, one failed after hundreds of cycles
and the second failed exactly after one cycle.
I can't program either one of them anymore.
The first one refuse to verify and the second
one verified but still contain the previous version.
If it's so difficult to program them, perhap I should
switch to PLCC (44 pins) socket rather than MLF (64 pins).

Re: OT AVR Flash
Jim Granville wrote:

That's what I did. The read back file (using the same
programmer, avrdude) is different from the new file.
Although I don't have the old version to compare,
the AVR is still running the older code.
I know the bootloader first store it in SRAM (1K),
but it could not have stored the whole file (10K).
The only thing I can think of is that the flash has
a long term memory (old file) and a short term
memory (new file).
We might have to reconsider the bootloader in
general and atmega169 in specific.

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