Arduino Forum

Using Arduino => Installation & Troubleshooting => Topic started by: Remittub on Jan 23, 2013, 11:18 am

Title: Chip reversal !!!
Post by: Remittub on Jan 23, 2013, 11:18 am
I'm ashamed to say that I have just fitted an ATMega328 to my Arduino Uno, but got the orientation wrong !!!!   (What a twit !! - I am now marking the pin 1 end with a blob of Tipp-ex on both chips  and board to hopefully prevent this happening again.   Have a damaged either the ATMega or the Arduino ??
Appreciate  any help  on this embarressing issue !!! :0 :smiley-roll-sweat: :smiley-roll:
Title: Re: Chip reversal !!!
Post by: Leon Heller on Jan 23, 2013, 11:28 am
Does it work?
Title: Re: Chip reversal !!!
Post by: Remittub on Jan 23, 2013, 12:16 pm
Yes, I   think it does, but haven't done too much testing yet ! (I move the chip to another board to use it) Thought that I should seek the advice of others first about whether I've done any damage (more worried about the Arduino obviously  - I can afford to lose an ATMega chip !)
Title: Re: Chip reversal !!!
Post by: Grumpy_Mike on Jan 23, 2013, 01:17 pm
Yes done it myself, it happens to us all.

No damage noticed but I won't go building it into a life support system.
Title: Re: Chip reversal !!!
Post by: Remittub on Jan 23, 2013, 01:48 pm

Yes done it myself, it happens to us all.

No damage noticed but I won't go building it into a life support system.


... so are you saying that I can carry on and use both without endangering anything ?? 
(Don't worry - I wouldn't trust my coding to anything vaguely important !!)

Thanks for your help, by the way - much appreciated !
Title: Re: Chip reversal !!!
Post by: Grumpy_Mike on Jan 23, 2013, 02:17 pm
Quote
so are you saying that I can carry on and use both without endangering anything ?

Yes indeed that is what I am saying.
Title: Re: Chip reversal !!!
Post by: CrossRoads on Jan 23, 2013, 04:01 pm
Look at the pinout for a '328,
When the DIP part is installed backwards, VCC/GND from pins 7/8 and up at Aref/GND at pins 21/22,
and Aref/Gnd end up at pins 7/8.
Avcc ends at PD4, and PD4 ends with  Avcc.
I think that's what save the part from being damaged.  Vcc and Avcc are not shorted out, Gnd is still at Gnd.
The bootloader/sketch are not started because the oscillator is not hooked up.
I've done this myself also (and have now marked my boards as well) and have not seen any damage occur - the chip does not get warm even, which is usually a good sign of excess current being drawn.
Title: Re: Chip reversal !!!
Post by: Remittub on Jan 23, 2013, 10:44 pm
That's great  !!  Thank you all for helping me out with your advice !  :)
Title: Re: Chip reversal !!!
Post by: eried on Jan 23, 2013, 10:51 pm
It is not only the dot, the chip has an indentation too :D
(http://forum.allaboutcircuits.com/image_cache/httpi97.photobucket.comalbumsl229dmc0162chip.jpg)

For me is easier to identify on low light using that shape :P
Title: Re: Chip reversal !!!
Post by: larryd on Jan 23, 2013, 11:48 pm
Helps to paint a large white large dot near pin one of the chip and the PCB.
Title: Re: Chip reversal !!!
Post by: Coding Badly on Jan 23, 2013, 11:55 pm

Finger nail polish is good for that.  I use a bright lime green color.  (Also works well on gun sites.)
Title: Re: Chip reversal !!!
Post by: stonent on Jan 24, 2013, 04:43 am
My board has the notch silkscreened on it, as well as the socket has a notch, as well as the chip having a notch.
Title: Re: Chip reversal !!!
Post by: retrolefty on Jan 24, 2013, 04:45 am

My board has the notch silkscreened on it, as well as the socket has a notch, as well as the chip having a notch.



Some need more of a hint then that I guess.  ;)

Lefty
Title: Re: Chip reversal !!!
Post by: Grumpy_Mike on Jan 24, 2013, 10:07 am
I use that liquid paper correcting fluid to mark the ends of plugs and sockets. I also put a dab by pin one when I have burnt a boot loader into a 328 chip.
Title: Re: Chip reversal !!!
Post by: dannable on Jan 24, 2013, 10:37 am
One of my 'knock off' boards has the socket, and therefore the notch, the wrong way round!
Title: Re: Chip reversal !!!
Post by: retrolefty on Jan 24, 2013, 04:20 pm

One of my 'knock off' boards has the socket, and therefore the notch, the wrong way round!


Wow, that's worst then the Asian E-bay seller the has leds with the reversed polarity option.  :D

Lefty
Title: Re: Chip reversal !!!
Post by: stonent on Jan 24, 2013, 05:20 pm

One of my 'knock off' boards has the socket, and therefore the notch, the wrong way round!


(http://i.imgur.com/jWotRUb.jpg)

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