Annoyed- Semidead JTAG Mk2 [solved]

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I guess there is no point reading past this unless you have a solution. But it's a free forum. :?

It seems I have lost nSRST (pin 6 of the JTAG header) therefore no ISP, PDI or DW functionality anymore :evil: JTAG seems to work as it doesn't use that line unless the JTD bit has been written to and the target cannot be reset for debugging/programming.

I have traced the signal to the SPST switch (top MAX312) and the nSRST switch input is idling at a suspicious 2.8V jumping briefly to 5V when trying to connect. The nSRST pin does not budge, it should go low when attempting ISP.

Does anyone know where the switch input is coming from? Is there (hopefully) a level shifter chip that might have blown up? If the actual M128 pin is blown then it will be pretty much beyound repair. :( :(

John Samperi

Ampertronics Pty. Ltd.

www.ampertronics.com.au

* Electronic Design * Custom Products * Contract Assembly

Last Edited: Sun. Dec 27, 2009 - 12:06 AM
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Try Chip Quik if you need to replace the M128:

http://www.chipquikinc.com/

I've used it for years.

Leon Heller G1HSM

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I'm showing my ignorance here. Be gentle.

Quote:

I have traced the signal to the SPST switch (top MAX312) and the nSRST switch input is idling at a suspicious 2.8V

That sounds like it's floating, which is what it should be doing when not trying to actively reset the chip.

Quote:

jumping briefly to 5V when trying to connect.

Have you verified that the right device is selected (dumb, I know)? The 8051 parts use 5V for RESET, while the AVR parts use 0V. It might be that your JTAG is confused, since the target reset polarity parameter is non-volatile and is only set when you switch between device architectures. Try switching to a 8051 part from AVRStudio, connect, switch back to an AVR part, and try again.

- Dean :twisted:

Make Atmel Studio better with my free extensions. Open source and feedback welcome!

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Quote:
Try Chip Quik if you need to replace the M128
If one of the M128 was the problem how would I put the bootloader in the chip when Atmel does not make it available? Maybe the chips are not locked and it could be sucked out from another JTAG.

But we'll look at that if necessary. I have a reasonably good SMD rework station and some Chip Quik, now if I could just buy a new set of eyes.. :? (cataract in righ eye ready for surgery in a few months :shock: )

Quote:
Have you verified that the right device is selected
Lots of them, tried JTAG, PDI, ISP and DW. I have a sneaking suspicion that the only confusion was in my head when if I plugged the squid PDI header back to front sending 3.3V to the nSRST pin.

It must have happened when plugging and unplugging the JTAG and Dragon to try SP1 (using different harnesses). :(

I'll look a bit more into it next week, the SPST chip seems to work OK but can't trace the pin back to the source. There are a few chips (Maxim) and one or more of them should be level translators.

John Samperi

Ampertronics Pty. Ltd.

www.ampertronics.com.au

* Electronic Design * Custom Products * Contract Assembly

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Thanks to moi there is now an open issue at atmel requesting a jtagicemkii selftest button in avrstudio, right next to the ice50 selftest button. If a hundred or a thousand jtagicemkii users now ask when that feature will be released, maybe it will get a little more traction. If there are any atmel employees reading this, can you post a link to how I can get my other jtagicemkii refurbed? Tech support says return it to from whence it was bought. Ha. They'll just exchange it. If its disposable, then send me a new one how bout?

Imagecraft compiler user

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Check this link to see if you have the same type of problem.

https://www.avrfreaks.net/index.p...

Regards
Dez Ellis

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Thanks Dez, I was suspecting one of those 3 chips mentioned in the above thread but Michael seems to have narrowed it down the MAX3379EEUD. So it could be the same problem here as JTAG still works.

John Samperi

Ampertronics Pty. Ltd.

www.ampertronics.com.au

* Electronic Design * Custom Products * Contract Assembly

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Well I think I got it licked! :)

After some more testing and 1 burned finger (excessive current making a resistor hot :( ) I decided to remove the SP720ABG TVS array which is just behind the flex lead connector.

As suspected there was a dead short between pin 3 (the nSRST pin circuit) and pin 16 V+. After removing the chip the JTAG sprung back to life with a M64 reading the signature. Plugged in another board with a M88 and was able to program a 6K hex file into the chip.

Just ordered 3 chips from my friendly Farnell shop and they should be here Tuesday or Wednesday. I will not tempt whatever one is not supposed to tempt until I have static protection back on. As to why it happened I'm not sure. Happy enough I did not have to replace smaller spacing chips, I have some on order from Maxim and hope I never have to use them.

John Samperi

Ampertronics Pty. Ltd.

www.ampertronics.com.au

* Electronic Design * Custom Products * Contract Assembly

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Well, congratulations John! Make a flesh sacrifice to the fire gods, and all is again well. Even with that unseasonal attitude recently expressed by your evil twin brother.

I still haven't heard from your pilot about your jet stopping by to pick me up for the beer guzzle in Melbourne. Not much time left, you know.

Chuck Baird

"I wish I were dumber so I could be more certain about my opinions. It looks fun." -- Scott Adams

http://www.cbaird.org

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Quote:
Even with that unseasonal attitude
So you think it must have been a punishment for not believing in an unhealthy older person (I'd like to see his cholesterol levels) wearing a suit sponsored by Coca Cola. :lol:

As a kid he never brought me any presents, it was always the "dead" on the 1st or 2nd of November (can't remember) leaving me presents during the night. For kids up northern Italy it was an ugly old witch (probably his wife?? ) on the 6th of January.

John Samperi

Ampertronics Pty. Ltd.

www.ampertronics.com.au

* Electronic Design * Custom Products * Contract Assembly

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OK new chip back in and it all seems well.

It's a bit a bugger when the debugger is buggered up. :lol:

John Samperi

Ampertronics Pty. Ltd.

www.ampertronics.com.au

* Electronic Design * Custom Products * Contract Assembly

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js wrote:
I guess there is no point reading past this unless you have a solution. But it's a free forum. :?

It seems I have lost nSRST (pin 6 of the JTAG header) therefore no ISP, PDI or DW functionality anymore :evil: JTAG seems to work as it doesn't use that line unless the JTD bit has been written to and the target cannot be reset for debugging/programming.

I have traced the signal to the SPST switch (top MAX312) and the nSRST switch input is idling at a suspicious 2.8V jumping briefly to 5V when trying to connect. The nSRST pin does not budge, it should go low when attempting ISP.

Does anyone know where the switch input is coming from? Is there (hopefully) a level shifter chip that might have blown up? If the actual M128 pin is blown then it will be pretty much beyound repair. :( :(

Hey John,

I checked the signals and I have quite the same problem as you wrote there. The reset is not going to 0V but arrround 2.5V. It can't initiate the communication. I am not so good in electronics. I read the rest of this topic and I am not sure what to do.

This is a damaged JTAG issue? What could cause this? How to solve it, replace a chip in the JTAG by a MAX3379EEUD?

Many thanks!

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If you pull the chip out it should just work. However if it all works again replace the chip ASAP and before you use it as it protects the rest of the inputs.

John Samperi

Ampertronics Pty. Ltd.

www.ampertronics.com.au

* Electronic Design * Custom Products * Contract Assembly

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Great, I will test it. But I have a new version JTAG ICE MKII and poeple say that only the old version is vulnerable. Is your JTAG first or second version?

js wrote:
If you pull the chip out it should just work. However if it all works again replace the chip ASAP and before you use it as it protects the rest of the inputs.

To make sure I do not break the whole thing:
I am confused because you said to replace the chip by another before I use the JTAG. How to know if it works if I don't use the JTAG? Do you mean test it (exemple: by entering a debug session) only once and then replace the chip?

Thanks! I can't believe that I'm on something!!!

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John,

Just wanted to let you know. I can still use the debug wire on a M168. The JTAG uses the reset line to communicates with the device. Isn't it contradictory with the burned MAX chip?

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Yes as both use the reset pin but maybe it's low enough to work on one but not the other.

The chip is only doing zap protection so it can be taken off and it should still work. However you no longer have zap protection with that chip out, so be very, very careful during testing.

You could also have other driver chips dead of course.

John Samperi

Ampertronics Pty. Ltd.

www.ampertronics.com.au

* Electronic Design * Custom Products * Contract Assembly

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Thanks,

I'll try that. Were your damaged JTAG a new or a old version?

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A version with B0xxx. I purchased it from another member so it was used but had worked well for about a year.

John Samperi

Ampertronics Pty. Ltd.

www.ampertronics.com.au

* Electronic Design * Custom Products * Contract Assembly

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John,

I removed the the tree MAXIM chips near the connector. One after the other stating with the MAX3392, then the MAX3391 and finaly the MAX3379. It still doesn't work but DW still works... I am really sutck and I need some advancement... So I ordered a brand new JTAG ICE MKII from Arrow, in special right now at 149USD and a bunch of new MEGA644. If it doesn't work after that, I'd better find a new job (kidding but still)...

Any other clues?

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Quote:
I removed the the tree MAXIM chips
Nooooo :shock: the only one I meant is the SP720ABG TVS. See above https://www.avrfreaks.net/index.p...

John Samperi

Ampertronics Pty. Ltd.

www.ampertronics.com.au

* Electronic Design * Custom Products * Contract Assembly

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:( OH!!

Ok, I was carrefull when removing the MAX chip, I put it back and removed the PS chip. It works now...

I am so happy!

John, thank you!
:lol:

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Quote:
I am so happy!
:-) replace the TVS chip ASAP or you will be very sad again.

John Samperi

Ampertronics Pty. Ltd.

www.ampertronics.com.au

* Electronic Design * Custom Products * Contract Assembly

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I'll do it. Thanks again.

I know where the problem comes from. A bad ground burned the chip. I willbe more carefull on my set ups.

Thanks again