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.
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:
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
Right, I do understand this - but the documentation is a little bit confusing.
I think it says that both pins 7 and 4 need to be connected to the same voltage but I thought that pin 7 was the actual power and pin 4 was just a signal? Therefore, for example, 5V on 7 and 3.3V on 4 would be OK?
Rog.
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
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).
How are you reprogramming them? What's the power supply?
I haven't had this problem, though I don't use that specific part.
The second sounds unlikely : ie How can it verify the wrong code ?
If they are not secured, you should be able to read back the code, and then compare with the nearest HEX version - that can give an idea of failure modes.
-jg
In self programming mode (boot loader), both with the on-board 3V battery and external 5V supply. We might need to switch to an external programmer.
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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