Pin 1?

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Going to guess that it's the top left. Not quite sure...never seen three corner dots on a single chip before. Atmega64 TQFP

Chris

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Chief Tinkerer

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I would have said top-right myself.

The datasheet says that the pin 1 marker is indicated by a circle in the plastic. From your photo, it looks like the biggest circle in the plastic is top-right.

If you want to increase your confidence factor, pins 22, 53 and 63 are GND. Check with your multimeter they are indeed shorted together before soldering the chip onto the board.

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Quote:

I would have said top-right myself.

The datasheet says that the pin 1 marker is indicated by a circle in the plastic. From your photo, it looks like the biggest circle in the plastic is top-right.

There's three dots, two are the same size. I'd be Cliff's next paycheck that pin 1 is located in the top-left in the picture, at the small dot.

- Dean :twisted:

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frankvh wrote:
I would have said top-right myself.

The datasheet says that the pin 1 marker is indicated by a circle in the plastic. From your photo, it looks like the biggest circle in the plastic is top-right.

If you want to increase your confidence factor, pins 22, 53 and 63 are GND. Check with your multimeter they are indeed shorted together before soldering the chip onto the board.

Ah good idea to check with the multi, I will do that. As for the circles, my camera didn't do them justice, but the top right and bottom left are the exact same. The only different one is the top left which leads me to believe that it's pin 1.

Chief Tinkerer

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Soldered it on and fired it up....AND.....no smoke. Pin 1 is confirmed as top left.

Thanks guys,

Chris

Chief Tinkerer

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The two larger ones are obviously something to do with the plastic moulding process.

Leon Heller G1HSM

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I found out the hard way recently with a LPC1769. Molding marks vs pin 1 mark.

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I can't see the problem with the LPC1769 if the data sheet is checked, they just have a single mark. It is in the bottom left corner, relative to the text, which might be confusing.

Leon Heller G1HSM

Last Edited: Wed. Sep 28, 2011 - 10:44 AM
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Is it just a photographic artefarkt or is the upper left corner cut a wee bit "wider" than the others?

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leon_heller wrote:
I can't see the problem with the LPC1769 if the data sheet is checked, they just have a single mark. It is in the bottom left corner, relative to the text, which might be confusing.

That's just mean. I'd say that >95% of TQFP's have pin one in the upper left relative to the text being viewed "right side up" on the component

Science is not consensus. Science is numbers.

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Quote:
I'd be Cliff's next paycheck
I didn't know that either you or Cliff leaned that way ;)

Regards,
Steve A.

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Yes I spotted that - worried me even more!

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Two thoughts:

    Sometimes there's a bevel or other distinction on the Pin 1 corner, as Johan may have picked up.

    Surely if we are PROPER programmers, we should call it Pin 0.

Cheers,

Joey

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leon_heller wrote:
The two larger ones are obviously something to do with the plastic moulding process.

...obviously

JohanEkdahl wrote:
Is it just a photographic artefarkt or is the upper left corner cut a wee bit "wider" than the others?

Must be the photo. I don't notice any difference when looking at it. The top left corner happens to be pin 1 though (which is also top left relative to the text on the chip).

Chief Tinkerer