Experiences with Mega328PB?

[Wojta]

Hey all,
Im building a weather station so I was recently looking at AVR chips that could be used. As a bit of arduino guy my eye obviously landed on the mega328P, Im pretty used to it so I was pretty stuck to getting that one.
However then I realized Atmel (Microchip to be exact) made a new version, the Mega 328PB. I thought it could be pretty nice to get my hands on a "new technology", some of the features are awsome to have but I have no idea how different is it from the standard 328P (not featurewise but programingwise, in C). Does anyone have a experience with that chip? Is it even worth it getting it? Im a bit scared it could introduce some bugs but as I read only rev. A had something wrong I think. Also I have these chips available in two types, ATMEGA328PB-AN and ATMEGA328PB-AU, I wasnt able to spot a difference, do you know of any?

Thanks,
have a great day!

[fmaimon]

All the differences are highlighted in this AN: http://www.atmel.com/Images/Atmel-42559-Differences-between-ATmega328P-and-ATmega328PB_ApplicationNote_AT15007.pdf

If you are interested only in code execution only, this note from the AN summarizes it well: "Code compiled for ATmega328 variants are compatible and can be executed in the ATmega328PB device. Whereas, reverse code compatibility is not guaranteed."

Regarding the AU vs AN difference, it is explained in the datasheet in the "Ordering Information" page.

[Wojta]

Yeah, thanks, just me being blind. Still I dont get the table with the different types. Is it that one of them is pb-free and the other one is not? Its obvious I guess but I just dont see it... 


Whoops, see it. The temperatures, right?

[FreddyVictor]

Also I have these chips available in two types, ATMEGA328PB-AN and ATMEGA328PB-AU, I wasnt able to spot a difference, do you know of any?

it's actually pretty obvious when you look at them: http://uk.farnell.com/w/c/semiconductors-ics/microcontrollers-mcu/8-bit-microcontrollers-mcu/prl/results?st=atmega328pb

[Wojta]

Also I have these chips available in two types, ATMEGA328PB-AN and ATMEGA328PB-AU, I wasnt able to spot a difference, do you know of any?

it's actually pretty obvious when you look at them: http://uk.farnell.com/w/c/semiconductors-ics/microcontrollers-mcu/8-bit-microcontrollers-mcu/prl/results?st=atmega328pb

Not that obvious, the chips shown on that page are AU and MU, Im looking for a difference between AN and AU. Maybe Im just not getting the markings, If so, sorry...

[Bruce Abbott]

Clock Failure Detection and Switching Mechanism is a new feature introduced in ATmega328PB. This
digital logic detects the failure of the Low power crystal oscillator, Full swing crystal oscillator, and external
clocks...

Full Swing Oscillator
Clock source options of the ATmega328 variants include full swing crystal oscillator, which can be
selected by configuring the flash fuse. However, in the new ATmega328PB, the full swing crystal oscillator
is removed.

[igendel]

Full Swing Oscillator
Clock source options of the ATmega328 variants include full swing crystal oscillator, which can be
selected by configuring the flash fuse. However, in the new ATmega328PB, the full swing crystal oscillator
is removed.

Yes, I almost lost a project/client because I was unaware of this "feature"...

[Wojta]

Thanks for pointing that out. Im pretty sure that would stop me for a while 

[Wojta]

I read a bit about the oscillator options and low power is the "closest" to the full swing right? Maybe Im saying it wrong. I mean the same crystal circuit still applies , but the max frequency it can run on that is 16Mhz, not 20. Am I correct or mistaken again?



Thanks for your patience with me guys 

[igendel]

I mean the same crystal circuit still applies , but the max frequency it can run on that is 16Mhz, not 20. Am I correct or mistaken again?

My design (with a regular 16-MHz HC49 crystal) failed, that's how I learned about this issue in the first place. But maybe crystals with different/high quality specs will work.

[L1L1]

As part of an IoT project, I paired a 16Mhz crystal with an Atmega328PB and it works just fine.

FYI, it's an Abracon ABM3-16.000MHZ-B2-T.

It's true that the signal on the atmega's clock pins is rather weak but it seems to be enough nevertheless.

Here's a write-up with more details: http://omzlo.com/articles/using-an-external-crystal-on-the-atmega328pb

[Wojta]

Lovely, thank you.

[colorado.rob]

I've been using the inexpensive Epson TSX-3225 16MHz 9pF crystals with my 328PB parts with good success.  They're about 30% less than the Abracon part.

[L1L1]

I've been using the inexpensive Epson TSX-3225 16MHz 9pF crystals with my 328PB parts with good success.  They're about 30% less than the Abracon part.

I tried those as well with a 328PB. While I had no trouble soldering them with hot air, I got a lot of failures once I moved to a reflow oven. Not sure why.

The Abracon part is easier to handle. In fact you can even solder it with a regular iron.

[colorado.rob]

I tried those as well with a 328PB. While I had no trouble soldering them with hot air, I got a lot of failures once I moved to a reflow oven. Not sure why.

That's really odd.  I have a reflow over and hot-air rework station.  Almost all boards done these days with reflow (cheap T962) by me and by my board manufacturer.  I can't say I have ever seen a crystal failure.

What you say really doesn't make sense to me since reflow is easier on the crystal than hot air since you have a well-regulated temp profile.