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Author Topic: Whats The Difference Between The ATMEGA328-PU and the ATMEGA328P-PU ????  (Read 2516 times)
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hello & Good-Day to you all !!

I am looking to buy 5 microcontrollers but want the ATMEGA328 but there are two types and i can find any difference in the data sheets about them, please could anyone help me find out the difference ?

There is Either the:

ATMEGA328 PU                     OR:


and i am really struggling to find the list of differences as i did find a webpage that details all the differences (i think there was 4 or 5 differences but cant remember it was so long ago & didnt bookmark the page! )

Please could any of you legendary Arduino Guru's help me with this ???

Many many thanks in advance for any help given !

Si Vis Pacem, Para bellum
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New true random number library available at:

Current version 1.0.1

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Author of "Arduino for Teens". Available for Design & Build services. Now with Unlimited Eagle board sizes!
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Signature Bytes are different

ATmega328   0x1E 0x95 0x14
ATmega328P 0x1E 0x95 0x0F

328P has some subtle feature differences that most users will not notice.

You can copy a portion of avrdude.conf & make a new part for the 328's, and do the same in boards.txt.

Designing & building electrical circuits for over 25 years. Check out the ATMega1284P based Bobuino and other '328P & '1284P creations & offerings at
Arduino for Teens available at

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