Damaged AVR's

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I am pretty new to AVR's and electronics in general. I only recently learned how to solder on youtube.

In my ignorance, I have miss-wired chips, done poor soldering jobs etc and after I do this, sometimes the micro controller stops working. I have two in a box but I also threw away two before I decided to start saving them. Last night I was soldering the pins on a atmel butterfly and some how a little solder ball landed right between the mcu and a little capacitor, connecting 3 pins to each other and the cap. Of course, I powered it up before I noticed the problem and it didn't work work. I removed the battery and then the ball with a small tug of some some tweezers, and nothing!

Up till now I have assumed that microcontrollers are delicate things and can die if you do something wrong. But, while reading through this forum I came across this post

Quote:

david.prentice - Jun 06, 2010 - 06:28 AM
Post subject: RE: Re: RE: AVR damaged? How about a photograph of the kitchen table, AVR, clothes pegs and crystal?

As a general rule, AVRs work just fine until you emit smoke from them.

If you have not seen or smelled any smoke, the AVR is fine. Your wiring is crap.

David.

So I have not seen any smoke yet but I have seen dead micros. Is there any way to bring my butterfly back to life?

Thanks
Hyrum

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The pins on the outside of the package are connected to the die with bonding wires. Over current usually destroys the bonding wire, which you cannot repair. Often only that pin is then unusable, but depending on which pins you shorted, the chip could be completely dead.

So which 3 pins got connected together and to what signal ?

"Debugging is twice as hard as writing the code in the first place. Therefore, if you write the code as cleverly as possible, you are, by definition, not smart enough to debug it"

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thygate wrote:

So which 3 pins got connected together and to what signal ?

I don't have it with me so this crude MS paint edit from a picture I found online is the best I can do right now. Looks like it connected pins 49, 50, 51 (PA1,2,3 or com0,1,2) to VCC.

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It's hard to say if the chip is still okay.
If I power my pcb up for the first time, I start with very little current and low voltage. If the current stays low, I increase to normal voltage.

Most of the times the chip is still okay after some bad soldering or a solder drop. When I started with AVR chips, I threw away what I thought was broken. Now I know that they don't get broken so easily, and that it was probably not broken at all.

Suppose you really had a shortcut, and the chip was getting hot, it could be damaged. But then again, it's hard say from here if it is really broken.

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Kun.io wrote:
It's hard to say if the chip is still okay.
If I power my pcb up for the first time, I start with very little current and low voltage. If the current stays low, I increase to normal voltage.

How do you do that? With some kind of special power supply?

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it's common practice to test new circuitry that way when powering up for the first time or after changes.
A decent lab power supply has a current limiter.

Maybe only those pins are dead, maybe the whole mcu.
Perhaps there is still a short somewhere cause of something else that broke (some sensors that were connected to the adc on those pins)
try measuring the current.

"Debugging is twice as hard as writing the code in the first place. Therefore, if you write the code as cleverly as possible, you are, by definition, not smart enough to debug it"

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thygate wrote:
it's common practice to test new circuitry that way when powering up for the first time or after changes.
A decent lab power supply has a current limiter.

Thanks, I'll get one of those. Up till now I've just plugged it in and if the power LED I have goes dim I quickly unplug it.

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HyrumF wrote:
Kun.io wrote:
It's hard to say if the chip is still okay.
If I power my pcb up for the first time, I start with very little current and low voltage. If the current stays low, I increase to normal voltage.

How do you do that? With some kind of special power supply?


You could connect the MCU board via a 12 Volt incandescent light globe ( or say four 3.5 Volt torch globes in series).
If there is no fault (ie. no excessive current), the light globe probably won't even glow.
If there is a fault, the light globe will glow. As it gets hotter, it's resistance will increase & you will see it get brighter. In doing so, it limits the current into the faulty circuit and you get light from the light globe, rather than smoke from the MCU.
There was a special device called a baretter years ago, which was commonly used for that purpose(amongst other things).
It is really important when you are powering "a new circuit" from your PC's USB port, as a fault can cause a failure in your PC. This is particularly so for Arduino users who
a) run their systems from their PC.
b) fiddle with hardware on shields.

Under no circumstances DO NOT APPLY MORE THAN 3.3 VOLTS to the Butterfly board. You will damage it.

Charles Darwin, Lord Kelvin & Murphy are always lurking about!
Lee -.-
Riddle me this...How did the serpent move around before the fall?

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Good news! It works again!

I came home from work and pulled out my butterfly and it turned right on. I used alcohol to clean the board after soldering. Maybe it hadn't evaporated completely and was causing problems? Last night all I got was a few flickers from the lcd.

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Buy a good jeweler's loupe, (shown in This Thread ),so you can closely scrutinize the PCB(s) after you work on them, BEFORE you power them up.

JC

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What were you soldering to the butterfly?

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Atmel Studio6.2/AS7, DipTrace, Quartus, MPLAB, RSLogix user

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jgmdesign wrote:
What were you soldering to the butterfly?

I was just soldering some headers on it so I could start messing with it.

I ordered a power supply and a loupe.

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It's been a long time since computers blew up and shot fireworks like in movies ;)

Usually if you just short a couple pins, removing the short solves the problem. Of course, it depends what you short them to. I have a tiny board in a 24v system and when I shorted the +5 to the +24, the result was almost impressive. Model railroaders are always looking for ways to make black smoke

I like to take advantage of our high impedance CMOS stuff, and sometimes a bit of resin or something looks like a short.

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