What is the difference between Atmega's?

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Hi all,

I've been messing around with Atmegas for a while now and I'm loving it! One thing that keeps popping into my head though is 'What's the difference between these chips'.

When looking through the range of Atmega's on the Atmel site I'm seeing loads of different chips and when reading the data sheets I'm seeing a lot of the same info.

Is the core CPU in each of the Atmega range based on the same design, each with a different set of peripherals and memory/storage options, or is there more to it than that?

Thanks

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Yes. :wink:

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Just walk into a BMW shop. Each and every car there will carry the BMW brand. But some might just fulfill the basic needs of someone who needs a car driving from A to B without getting wet (ok, you wouldn't actually need a BMW for that...). Others might need navigation, electric windows, a bar at the rear seats, 250 HP, a sports package, and so on. This - plus the different price tags - serves to address different needs and wallets of the potential buyer.

Einstein was right: "Two things are unlimited: the universe and the human stupidity. But i'm not quite sure about the former..."

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Quote:

Is the core CPU in each of the Atmega range based on the same design

Close. There may be subtle differences like a "big one" has ELPM whereas small ones only have LPM but otherwise, on the whole. As the product selector on atmel.com shows it's the peripherals around the CPU that differ from one model to the next. Of course there's also things like power considerations. Some chips are "Picopower" some aren't. And you can get "megas" in anything from 28 to 100 pin packages - the big ones having more on board than the small ones.

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Have you been here?
http://www.atmel.com/products/se...
or here?
http://www.atmel.com/products/mi...
(find Atmel Flash Microcontroller Product Portfolio )

You can put lipstick on a pig, but it is still a pig.

I've never met a pig I didn't like, as long as you have some salt and pepper.

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Wow you guys are quick, I had only read a few other posts lol.

Thanks for the responses, I thought that's how it worked (like the BMW example BTW lol). I bought a few 'p' chips, the 644p and 1284p, that got me reading about picopower so I'm glad that was brought up. Now .... Time to read up on what ELPM and LPM is :p

I had noticed the focus around the peripherals and it was the lack of info on the 'core' that made me wonder. I can see why though, even in the silly projects I've been doing to learn about mcu's/electronics I have found myself regularly thinking things like 'I need more I/O's' or 'A second UART would be handy'.

Thanks again :)

Edit: Thanks for those links, I'll have a good read. There is a good chance I've been there. I feel like I've read the entire internet and still know very little lol. Getting there though.

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Quote:

time to read up on what ELPM and LPM is :p

www.atmel.com/images/doc0856.pdf‎

Also note that in the "features" page of each AVR datasheet it says something like "133 powerful opcodes" yet some will say something like "136 powerful opcodes".

(Both are actually a lie - there's only about 60-70 opcdes as some of the 130-136 are synonyms)

But that will show which ones have those few extra opcodes like ELPM.

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And I was going to be snarky and say, "One of its feet are both the same."

If you don't know my whole story, keep your mouth shut.

If you know my whole story, you're an accomplice. Keep your mouth shut. 

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Quote:

... it was the lack of info on the 'core' ...

??? Maybe I'm just too close to things. How much more information on the "core" was there in x51 or Moto 68xx datasheets?

In the datasheet for the AVR model, there is a more or less detailed block diagram. Yes, one big chink is "ALU".

When the instruction carried out might affect an I/O register (peripheral subsystem) there is information on that in the various sections.

For each instruction, there is an entry in the "AVR Instruction Set" document as well as general descriptions of e.g. comparison operators.

What part is missing?

You can put lipstick on a pig, but it is still a pig.

I've never met a pig I didn't like, as long as you have some salt and pepper.

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Oh, yes, there is a whole chapter in the datasheets on "AVR CPU Core". Architecture, pipelining, GP registers, status register, ...

You can put lipstick on a pig, but it is still a pig.

I've never met a pig I didn't like, as long as you have some salt and pepper.

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8buttons wrote:
One thing that keeps popping into my head though is 'What's the difference between these chips'.

And just to confuse things even more, is this

[" Atmel will be launching six new 4k to 16k Flash devices in the AVR® Mega MCU family in the second quarter 2014 ...The new AVR MCUs will be manufactured using advanced 130-nm CMOS technology "]

I cannot find any hard info, on if these 'new' Mega's run as fast as xMega's (or faster?) or if they have Wide, or Narrow supply Voltage support ?

(Atmel has been poor at supporting wide Vcc, so poor that the upcoming new small USB parts, seem unable to power from VBUS ?! )

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From the same press release:

Quote:
Fosters Compelling Ideas From AVR Loyalists to Bring Imagination to Reality

...whatever that means. As a fan-boy, is that me?

Quote:
"With over 200,000 loyalists in our AVR Freaks community ..."

I think that has been questioned before.

Anyway, "130-nm"--what is the current feature size of AVR "A"? I forget.

You can put lipstick on a pig, but it is still a pig.

I've never met a pig I didn't like, as long as you have some salt and pepper.

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Quote:

I think that has been questioned before.


There's supposed to be well beyond 100,000 Arduino users - I guess they are "AVR Loyalists" too? (even though some may never have even heard of Atmel/AVR ;-))

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Quote:

There's supposed to be well beyond 100,000 Arduino users - I guess they are "AVR Loyalists" too? (even though some may never have even heard of Atmel/AVR Wink)

Let me quote the complete sentence:
http://ir.atmel.com/releasedetai...
Quote:
Reza Kazerounian, Senior Vice President and General Manager, Microcontroller Business Unit, Atmel Corporation. "With over 200,000 loyalists in our AVR Freaks community and 1.2 million Arduino development boards in the Maker community, our AVRs have definitely made a significant impact in today's Maker and hobbyist circles. With over 65,000 active users in our Studio 6 integrated development environment, we are making it easier for all designers to access our tools."

Unfortunately, the Web site tools don't let me get a count of the "Memberlist". And we all know that a sizable chunk of the "members" have no posts or very few posts.

You can put lipstick on a pig, but it is still a pig.

I've never met a pig I didn't like, as long as you have some salt and pepper.

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Philosophical question: do you have to have posted to be a "member of the community"? Do "lurkers" count?

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Quote:

Reza Kazerounian, Senior Vice President and General Manager, Microcontroller Business Unit, Atmel Corporation. "With over 200,000 loyalists in our AVR Freaks community [...]

[imaginary whispering he continued] "..we still don't think it has been important enough to give AVRfreaks the facelift it deserves for half a decade."

Marketing in a nutshell. Slgithy worse than lawyers. On par with journalists. Slightly better than politicians.

Reza knows he is b-sh*tting here, and that there are no way near 200K ative 'freaks. He rubs his ego with it, Then pseudo-journalists printing press-releases verbatim as if they where journalistic work thrive on it, publishers letting all this go on because having journalists actually do journalism would lower the profit, readers (yup - that's you and me) accepting this because they like their tech publications for free and nothing in return.

As of January 15, 2018, Site fix-up work has begun! Now do your part and report any bugs or deficiencies here

No guarantees, but if we don't report problems they won't get much of  a chance to be fixed! Details/discussions at link given just above.

 

"Some questions have no answers."[C Baird] "There comes a point where the spoon-feeding has to stop and the independent thinking has to start." [C Lawson] "There are always ways to disagree, without being disagreeable."[E Weddington] "Words represent concepts. Use the wrong words, communicate the wrong concept." [J Morin] "Persistence only goes so far if you set yourself up for failure." [Kartman]

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Quote:
With over 200,000 loyalists

199,999.

No RSTDISBL, no fun!

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Quote:

199,999.

LOL, coffe-through-nose and all that!

As of January 15, 2018, Site fix-up work has begun! Now do your part and report any bugs or deficiencies here

No guarantees, but if we don't report problems they won't get much of  a chance to be fixed! Details/discussions at link given just above.

 

"Some questions have no answers."[C Baird] "There comes a point where the spoon-feeding has to stop and the independent thinking has to start." [C Lawson] "There are always ways to disagree, without being disagreeable."[E Weddington] "Words represent concepts. Use the wrong words, communicate the wrong concept." [J Morin] "Persistence only goes so far if you set yourself up for failure." [Kartman]

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Quote:

Philosophical question: do you have to have posted to be a "member of the community"? Do "lurkers" count?


Well, remember that the quote used the word "loyalists".

Let's do some backwards arithmetic. Cliff has 68118 posts which is 6.16% of the total posts. That would be 1,105,800 total posts; call that 1.1 million.

The top 50 loyalists -- err, 'Freaks -- in post count have 414,407 posts. 37.5% of the total.

Number 50 has about 3000 posts. I'd guess the next page might average 1000? So 100 of 200,000 have about 1/2 the total posts.

That leaves 600,000 posts for the other 200,000 AVR Freaks loyalists, or an average of 3 posts each. Is that, by any definition, a loyalist?

Quote:

Quote:

199,999.

LOL, coffe-through-nose and all that!


I guess HWMNBN could be called an AVR loyalist. What about Leon? :twisted:

You can put lipstick on a pig, but it is still a pig.

I've never met a pig I didn't like, as long as you have some salt and pepper.