Mega1284A Bricked.

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OK, not my week.

Mega1284A not responding to ISP at all. AVRISPII, STK500, Studio 4.18 SP3.

No I haven't changed any of the fuses. Only power, SPI and two port pins connected to more than just tracks (all correctly). No shorts.

Internal oscillator running as a 1 MHz square wave on the xtal out pin, but it is only about 10mV.

I'm not used to running AVRS on the internal oscillator, is this very low level normal, or is it a clue that soomething internal is dragging the oscillator down?

I suspect I may have bricked this one, possibly by a static zap (that would be the third or fourth time in nearly 40 years playing with cmos).

Cheers,

Joey

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You only get a clock output if you use the CKOUT fuse.
The virgin m1284 does not come with CKOUT fuse.

If you can see a 10mV signal, it is probably just your bad decoupling.

OTOH, you have a STK500. Use it. Set voltage levels. Read voltage levels. Even use HVPP if you need to.

However, if you have never changed fuses, you can never brick your AVR without the aid of smoke.

David.

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No man can accuse me of bad decoupling and live! :-)

I have truckloads of caps everywhere and there's nothing on the supply lines, I wonder if the feed through suggests something internal is awry.

Quote:
Even use HVPP if you need to.

Now there's a scary thought. dozens of flying leads randomly tacked to my beautiful pcb :( I suppose it's one way to spend an evening.

Cheers,

Joey

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Ah-ha. If the mega1284 is SMD on an external board, I would never consider HVPP. If it is DIP, you simply install in the STK500 socket.

If you are seriously suspicious of smoke or high voltages, other components suffer too.

Only you know what is practical. A new pcb + a new AVR is often the simplest choice.

David.

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Quote:

A new pcb + a new AVR is often the simplest choice.

Not with a TQFP64 and three other smds already in place :(

I suspect it must have got bricked some time ago. It will be a challenge to get it off without lifting any tracks, but do I wait for a direct replacement or pop in a Mega16 already in stock which will do the job, but won't give room for improvements?

Cheers,

Joey

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Quote:

It will be a challenge to get it off without lifting any tracks

This is why God invented paint stripper guns. Blast the chip with some hot air for a while until the solder looks "moist" then bang edge of PCB on table - chip falls off. (maybe the others too - but you can put them back afterwards).

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If you have never programmed fuses on the mega1284 then you cannot do anything serious. Anyway, the mega1284 does not even have a RSTDISL fuse.

So if you are seriously considering a 'bad voltage' accident, all your other chips are suspect too!

A whole new pcb is probably cheaper than your time and aggravation.

A bad soldered joint, track, short ... are all more likely than a bad chip from the factory. Get out that magnifying glass.

David.

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Try setting the isp frequency on AVRISP II to the lowest... 62.5K?
Can you read the signature?
Try setting the clkout fuse bit... do you see 1Mhz on the port pin?
You didn't say what makes you think it's bricked. Can't read the ID sig ?

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If it's zapped .... it's game over.
If it's a bad fusesetting ... why not give it a 1MHz 5V square wave (created by another AVR) and inject that into Xtal1-pin ? No need to remove the existing crystal or caps: it's a kind of brutal overruling ;)

A GIF is worth a thousend words   They are called Rosa, Sylvia, Tessa and Tina, You can find them https://www.linuxmint.com/

Dragon broken ? http://aplomb.nl/TechStuff/Dragon/Dragon.html for how-to-fix tips

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clawson wrote:
This is why God invented paint stripper guns.
And Chip Quik :)

"Dare to be naïve." - Buckminster Fuller

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One Idea I've come across is making a copper or brass square to fit round the chip and heat all the pins at the same time.

Cheers,

Joey

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If you suspect the chip is dead and want to replace you probably don't care if you destroy it removing it. So use some sort of tool to cut the leads off the chip right next to the chip. Fine cutting pliers, a Dremel cut off wheel (CAREFULL!!!!) a razor saw, or an xacto knife or saw. Then you can get the chip body off leaving just the leads which you can no unsolder with a solder sucker. Better destroy the chip than the board if you're sure the chip is fried anyway.

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As my kindly supplier has already put a replacement in the mail FOC, it will be the Dremel option.

Or I could mill it off ;-)

Cheers,

Joey

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And its arrived, in a waffle, in a big anti-static bag, in a bundle of brown paper, in a box at least two feet long.

A small anti-stat envelope in a jiffy bag (or even a normal envelope and a bit of cardboard) would have been fine.

No wonder the pklanet is going to the dogs...

Cheers,

Joey

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joeyAVR wrote:
As my kindly supplier has already put a replacement in the mail FOC, it will be the Dremel option.

Or I could mill it off ;-)


A CNC mill with a fine tip cutter would do it with surgical precision. :D

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I'm not sure I should admit this - I waved a turbo-flame lighter at it for a while, then banged the board and the chip and an smt cap fell off.

Popped on the replacement and it worked first time.

Cheers,

Joey

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joeyAVR wrote:
I'm not sure I should admit this - I waved a turbo-flame lighter at it for a while, then banged the board and the chip and an smt cap fell off.
Popped on the replacement and it worked first time.
Hot air rework gun would have done the same thing. At least you only lost one cap, not bad!

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Just out of curiosity, how long is "a while"?

Science is not consensus. Science is numbers.

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About 5 seconds, guesstimated. Took a couple of tries as I refilled the lighter and the first time it flared a big soft yellow flame that engulfed a quarter of the board =:-o

The turboflame is my tool of choice for stripping old boards, it's great for getting caps and resistors off single sided boards quickly and in bulk. It has enough guts to get headers etc. off multilayer boards without starting a big fire ;-)

Cheers,

Joey