Could I have fried the atmega?

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Re: Could I have fried the atmega?

Postby Beamtreetaker » Sun Apr 13, 2008 11:50 pm

Funnily (okay, more or less) now the USB detection works again but I get those blocks on my screen again with the further effect that none of megadrums functions will work (apart from usb detection like I said), not even the bootloader.
It's really strange: The last days I got either the Megadrum functions and no USB, or I get USB but no other functions. Could this help finding a reasonable diagnosis?
I did not yet try the atmega resistor solution but will do this as soon as possible (had to compensate some missing sleep yesterday.....).
Also - maybe this is a very stupid question: How can I assure there's no shorts on my board? Is there a certain way to check this efficienctly? Perhaps checking all pins on incorrect conduction with all its imediate neighbours?? Need some advice here.
The same for checking bad soldering points: I spent some hours checking my board for bad lines, but everything I tested seemed correct and after dozens of tested pin combinations you start to question this approach. It's like finding the f**n' needle in the haystack...... How would you proceed?

I really already built up a strong relationship to my megadrum and don't want to let him down! :lol: :lol:
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Re: Could I have fried the atmega?

Postby Synthex » Mon Apr 14, 2008 8:56 am

Beamtreetaker wrote:The last days I got either the Megadrum functions and no USB, or I get USB but no other functions. Could this help finding a reasonable diagnosis?

Not really ... ;) ... What did you make meanwhile ? What changes ?

Beamtreetaker wrote:maybe this is a very stupid question: How can I assure there's no shorts on my board? Is there a certain way to check this efficienctly? Perhaps checking all pins on incorrect conduction with all its imediate neighbours?

Yes, check all pins, all nets, ... check power for all ICs, ... Test the PCB on a not conductive surface (paper, ...), ...

Beamtreetaker wrote:I really already built up a strong relationship to my megadrum and don't want to let him down! :lol: :lol:

I know that !!! :D
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Re: Could I have fried the atmega?

Postby dmitri » Mon Apr 14, 2008 9:06 am

I check for short circuits with a magnifying glass. If there is a thick short circuit, I resolder that place. I it is thin, I just break it with a scalpel or a sharp knife.
Also, try resitting all your ICs, i.e. taking them out of their sockets and then firmly resitting them again.
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Re: Could I have fried the atmega?

Postby Synthex » Mon Apr 14, 2008 9:12 am

And remember that the static electricity is dangerous for your components !!!!!
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Re: Could I have fried the atmega?

Postby Beamtreetaker » Mon Apr 14, 2008 2:36 pm

Synthex wrote:Not really ... ;) ... What did you make meanwhile ? What changes ?

Nothing but plugging out and in the usb connector.

dmitri wrote:Are the pins 6,7,8 and 9 of Atmega32 pulled to +5V over 10k-47k resistors?

Yes I did that now but still no change: One line of black blocks, no bootloader entering possible, no midi led, no midi events sent, just recognition of megadrum on my pc. :cry:

Should I really now try using the 12 Mhz USB crystal for the Atmega for testing purposes as Synthex said in the other 'problem-thread'?

Edit: Did one more round of cleaning with this stuff (http://produkt.conrad.de/45973183/kontakt-lr-400-ml.htm) and now megadrum works again, but no USB.... :| it's so weird!
Last edited by Beamtreetaker on Mon Apr 14, 2008 3:47 pm, edited 1 time in total.
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Re: Could I have fried the atmega?

Postby dmitri » Mon Apr 14, 2008 3:44 pm

If electrically everything is right, than it means you have lost both MegaDrum firmware and a bootloader. Make "ISP Programming cable" and write firmware using PonyProg.
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Re: Could I have fried the atmega?

Postby Synthex » Mon Apr 14, 2008 4:05 pm

Beamtreetaker wrote:Should I really now try using the 12 Mhz USB crystal for the Atmega for testing purposes as Synthex said in the other 'problem-thread'?

You need a 20 MHz crystal for the Atmega.

Beamtreetaker wrote: Did one more round of cleaning with this stuff (http://produkt.conrad.de/45973183/kontakt-lr-400-ml.htm) and now megadrum works again, but no USB.... :| it's so weird!

Strange ... could you send a photo or a scan of you bottom side ?
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Re: Could I have fried the atmega?

Postby Beamtreetaker » Mon Apr 14, 2008 4:56 pm

Hmmm, I think I can exlude it's the crystal now, because both seem to be working... just not at the same time.

I did shoot two macro photos of the bottom side of my pcb. Wow, this is really a good diagnosis tool as I see some really bad spots that I hardly did see with the eye.
Here they are: http://rapidshare.com/files/107457792/pcb_btm.rar

On the photo some parts look really scary and I think about resoldering them (although multí-meter checking {resistance} seemed okay so far)
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Re: Could I have fried the atmega?

Postby dmitri » Mon Apr 14, 2008 5:44 pm

The soldering itself seems alright to me, at least it is much better than mine. One note though: cut excessive leads shorter than you did in some places.
Since you're in some kind of dead end at the moment, I again recommend you to make an ISP cable and try to program Atmega using this cable.
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Re: Could I have fried the atmega?

Postby Beamtreetaker » Mon Apr 14, 2008 6:24 pm

Synthex, could you please provide me a high resolution image of the pcb layout, as this one (http://www.megadrum.info/forums/download/file.php?id=409) is a bit difficult to interpret at some points. I need the exact runs of the lines so I can debug my board sufficiently.

Also, I don't think the firmware is defect on my megadrum because, as I wrote, now atmega is functioning fine again (but still no usb detection).

Edit: Some more details to confuse you: USB detection WORKS if I enter the bootloader (which also works again now). When I then unplug USB and plug it in again (without bootloader) USB won't work ( = windows says device not detected)........... :?:
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