Difference between ATmega328, 328P and 328PU

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I got some chips in from Digi-Key, which were giving me the wrong signature byte. Here's what avrdude said about them:

avrdude: Device signature = 0x1e9514 
    avrdude: Expected signature for ATMEGA328P is 1E 95 0F 
    Double check chip, or use -F to override this check. 

I sent a query about this to Digi-key. Their response is confusing me a bit, hoping someone could clarify.

The order was for 4 ATMega328p processors - Digi-key part #ATMEGA328-PU-ND.

The response from Digi-key was

"The ATMEGA328-PU-ND is NOT a ATMEGA328P it's a ATMEGA328 so the signature should NOT
match"

Aside from the fact that what I ordered was a 328p and they seem to be telling me they sent a 328, I can't find a definitive statement of what the difference between -P and -PU is. Clarification would be welcome.

Thanks

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Not -P but just P. ATMega328 and ATMEGA328P are almost same chips but manufactured with different tecnological processes. The suffix (-P, -PU etc.) shows just a package related information which is clearly described in RTFM.

Warning: Grumpy Old Chuff. Reading this post may severely damage your mental health.

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328P is not the same as 328-PU. The P in the first case indicates picopower. The P in the second case indicates the package (PDIP). If you wanted the picopower chip in a PDIP package, you should have gotten ATMEGA328P-PU.

Regards,
Steve A.

The Board helps those that help themselves.

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I think you'll find the differences are just in the silicon and affect the power consumption. In terms for functionality and pin compatibility (and programming) there is no difference.

--greg
Still learning, don't shout at me, educate me.
Starting the fire is easy; the hardest part is learning how to keep the flame!

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Koshchi wrote:
328P is not the same as 328-PU. The P in the first case indicates picopower. The P in the second case indicates the package (PDIP). If you wanted the picopower chip in a PDIP package, you should have gotten ATMEGA328P-PU.

So the signature bytes will be different then?

Thanks

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Quote:
In terms for functionality and pin compatibility (and programming) there is no difference.
Not quite true. There are a couple of differences that could be important when using the picopower functionality. For one, the BOD disable is not available on the non-P part.
Quote:
So the signature bytes will be different then?
Yes, they are different chips.

Regards,
Steve A.

The Board helps those that help themselves.

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Quote:
There are a couple of differences that could be important when using the picopower functionality.
Granted.
Very, very similar, though not identical, then ;)

--greg
Still learning, don't shout at me, educate me.
Starting the fire is easy; the hardest part is learning how to keep the flame!

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I got caught out by this at first, confusing the PU with picopower. IIRC the part of TFM (or datasheet) you need to refer to is Ordering Information. :wink:

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Koshchi wrote:
Quote:
So the signature bytes will be different then?
Yes, they are different chips.

Bummer, doesn't look like avrdude supports 328. Guess I'll have to do some reading to add it to my config file.

Thanks

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Quote:
Guess I'll have to do some reading to add it to my config file.
It's trivial. Just copy the existing 328x entry, and paste it after that section, then replace the sig bytes. Done.

--greg
Still learning, don't shout at me, educate me.
Starting the fire is easy; the hardest part is learning how to keep the flame!

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Great, easy is good, avrdude sees them now.

Thanks