DebugWire and JTAG Debugging: AVR Dragon vs JTAGICE MkII

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Apart from 32K flash limit, What else if different between AVR Dragon and JTAGICE MkII when debugging?, Is in both, AVR Dragon and JTAGICE MkII, the program running at the target device?

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Iirc the Dragon also will not do PDI, which is on the Xmega. The Dragon is a great value for starting out with.

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Quote:
Is in both, AVR Dragon and JTAGICE MkII, the program running at the target device?
Yes. Dragon is a bit more delicate, in spite of the name, :? than the JTAG Mk2.

The Dragon has also a small development area where you can plug in a chip and run your code. The JTAGICE MkII needs a separate target board for development.

John Samperi

Ampertronics Pty. Ltd.

www.ampertronics.com.au

* Electronic Design * Custom Products * Contract Assembly

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Thank you for your replies.

So, May I consider both equivalent when doing JTAG and DebugWIRE debugging if used with less than 32K flash devices? If this is true then I am going to consider Dragon since it can additionally do Parallel and high voltage programming which could be very useful in recovering a microcontroller if some configuration bit go wrong. A protection box, a ZIP socket and some headers soldering will be required to make it more robust.

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Yep, the Dragon is nice most of the times unless it goes into tantrums.

But if the special is still happening on the JTAG Mk2 at half price, it is a good buy.

John Samperi

Ampertronics Pty. Ltd.

www.ampertronics.com.au

* Electronic Design * Custom Products * Contract Assembly

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John, thank you again for your advice.

js wrote:
unless it goes into tantrums.

What do you mean? What kind of tantrums?

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HA...but you have to experience them. :) If it's of any consolation the JTAG Mk2 can also do tantrums.

Maybe the newer version of the Dragon is a bit better. Make sure that your USB connector supplies enough current or better still feed the Dragon from a powered USB Hub.

John Samperi

Ampertronics Pty. Ltd.

www.ampertronics.com.au

* Electronic Design * Custom Products * Contract Assembly

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I don't think the USB boost converter is an issue when using the Dragon with externally powered boards, apart from not touching it during operation. The failures I've read about don't say how it was used or to how big a device.

I've used it extensively with the Raven MCUs and wore out the flash on a BC100 644p, but I've only used the onboard socket for high voltage programming of bricked tiny85s. When I ordered it a year ago I got a ZIF socket for big MCUs, but I won't be using that until I see some reports of routine use with onboard megas.

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> What do you mean? What kind of tantrums?

I'd put it this way: when you need cheap Debugwire, the Dragon rocks... but buy the Dragon as your SECOND AVR programming device. Don't ever put yourself in a position where a Dragon is your one and only means of flashing an AVR for routine daily programming, because you'll either fry it or be frustrated & miserable on a regular basis.

Basically, the Dragon has three design fla^h^h^h compromises made in the name of value engineering that are generally tolerable for a device that gets pulled out for special occasions (debugwire, high-voltage resurrection of a comatose fuse-scrambled AVR, etc), but are fairly serious for a device you depend on daily.

1. USB-powered. More often than not, it seems like there are lots of devices that are "USB-powered" where the engineers screamed that 500mA was suicidal, and management said "It'll be good enough for 98% of our users, and will save us the $3 or so a brick costs to buy, ship, and sort by country". First-gen Dragons have a particularly nasty outright flaw whereby attempting to do high-voltage programming from a PC (or especially a laptop) USB port instead of from a powered hub can (and eventually will) fry parts on the Dragon. Search AVRfreaks for "Dragon-Slayer", and you'll see this is the #1 cause of Dragon death.

2. Most decent AVR programmers practice "Safer Programming" and buffer themselves from the devices they're having intimate relations with. Not so with the Dragon -- it likes it raw & nasty. As in real life, this causes it to come down with everything from transitory ailments that go away when you disconnect it and leave it alone for a while all the way to maladies that will kill it outright.

Specifically, nearly everyone with a Dragon and some other programmer has seen situations where the Dragon couldn't reliably program the target -- or even read the chip's id -- but their other programmer yawned, flashed it, and metaphorically asked what the big deal was. The Dragon is finicky about things buffered programmers don't even notice. In a well-equipped corporate development lab staffed by real engineers, those problems rarely happen. In your bedroom working on hobby projects, they most certainly will.

3. The Dragon is kind of like a cat -- there are certain places it simply does NOT like to be touched... except instead of just giving you a nasty scratch (shock) that will heal, it'll kill itself instead if you touch it wrongly at a particularly inappropriate time. IMHO, there's no excuse. It's understandable that Atmel wanted to save the case costs to keep it more affordable. It's unforgivable that they didn't do a better job of designing its paper carton to BE the Dragon's de-facto enclosure. A little origami, some dotted lines, maybe the inclusion of a single-edged razor blade to make cutting it easier. The point is, this is another major cause of DragonDeath.

In summary, if you own a Dragon as your SECOND programming device, you'll love it and be glad you have it when the need arises. If you buy one to be your one & only programmer, you'll regret it. And right now, for a little more than you'd spend for a Dragon and AVRISPmkII if you factor in two overnight shipping charges, you can buy a JTAGICE2 and enjoy the best of all possible worlds.

There's no place like ~/

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miamicanes wrote:
In summary, if you own a Dragon as your SECOND programming device, you'll love it and be glad you have it when the need arises. If you buy one to be your one & only programmer, you'll regret it. And right now, for a little more than you'd spend for a Dragon and AVRISPmkII if you factor in two overnight shipping charges, you can buy a JTAGICE2 and enjoy the best of all possible worlds.
Thank you for your detailed answer.

In fact, I am an amateur and probably will not program AVRs on a daily base. Probably 10 days per year. I will reconsider my decision.

Since I live outside USA I will end paying for a Dragon (shipping to my country + customs services + taxes) what you could pay for a JTAGICE2 inside USA.

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If you are livin in Europe, you can order it over here with good warranties, without customs hassle and fast delivery.

Guillem.
"Common sense is the least common of the senses" Anonymous.

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Here is a thread that talks about the new Dragon PCB, and has some links to a few DIY upgrades.
https://www.avrfreaks.net/index.php?name=PNphpBB2&file=viewtopic&t=79959

--- bill