Device Recommendation

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I've been using an ATMega128 for a while now & am pretty familiar with it... but have read posts where people speak of it as being pretty out-dated... Is there a newer device that's pretty close to the same as the ATMega128 I could use instead if this is actually the case? I've tried searching through the device descriptions but I can't get a feel for how old or new they are from doing that... So I'm worried I will pick one out that sounds like just what I want, but perhaps is about to go obsolote...

Thanks,
James

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Take a look at ATmega1281 and 2561.

Steve

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Atmel is not too bad when it comes to obsolete devices. I do not remember all AVR types ever made by heart, but I don't think I have ever seen one of the general AVRs going obsolete without a reasonable replacement.

It is more the other way around. Atmel is IMHO bad when it comes to new devices. They might be announced, but availability is bad.

If the ATMega128 has what you need, and you get them at a good price, why not stick with it? If you want to change, check distributors if the new one is available in quantity.

Stealing Proteus doesn't make you an engineer.

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I've found that M1281 in reasonable quantities will be cheaper than M128, with some more and nice features (three 16bit timers more, and double amount of RAM, IIRC). But M128 is far from being 'obsoleted', IMHO.

Guillem.
"Common sense is the least common of the senses" Anonymous.

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I just looked it up (should have done it earlier).

The mega128 is no longer recommended for new design, but still available from distributors. The successor is the mega128A. However, that one is not available from distributors (typical Atmel :-().

Since the 128A is not available, I wouldn't plan for it at all. I would stick with the 128, because one can still buy it, or I'd move to some other available chip. The key is availability, not what Atmel announces.

Stealing Proteus doesn't make you an engineer.

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I guess the most modern step up from the 128 might actually be the ATXmega128A1 in fact?

Same kind of price but LOTS more goodies.

(when they work that is! ;-))

Cliff

PS There is a bit more of a learning curve than a 1280 and you may need a new programmer.

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Quote:

I guess the most modern step up from the 128 might actually be the ATXmega128A1 in fact?

Most modern, perhaps, and more goodies, certainly.

However, the pinouts are vastly different and wouldn't be a drop-in or even a minor board tweak.

On the other hand with perhaps a few tweaks here and there (ISP pins for one), any of the following families use the same footprint and basic pin layout:

-- Vcc's line up
-- Gnd's line up
-- Aref lines up
-- ADC pins line up
-- XTALn pins line up

==> Mega64/128 family; A or not
==> Megannn1 family (the '1281 and '2561 mentioned above)
==> AT90USBnnn6/7
==> Mega169/329 family
==> Mega165/325 family

Similar can be done with 100-pin centipedes IIRC (but check for sure): '1280, '3290, '3250.

Cliff, as the model you mentioned is 100 pin and OP is talking 64 pin, isn't that kind of apples and oranges? I might as well then recommend a 48-pin (or whatever) SAM7 or something.

Lee

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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I didn't see him say anything about needing a pin-equivalent device? But I agree that Xmega is a vastly different device - just that in terms of 128K flash AVRs it maybe represents the current pinnacle.

The difference between using an Xmega and a SAM7 is that you can almost certainly use the same compiler as you've been using previously (maybe updating to the latest version). If you are lucky enough to own AVRISPmkII or JTAGICEmkII you may not even need to buy new programmer/debugger electronics either (you most definitely would if you moved to ARM)

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Cliff, many ARM's have some sort of HW coded bootloader, so no need for programmers. At least for the few I know of (AT91SAM7S/X, STM32). GNU compiler for ARM's is a well stablished technology that is quite madure and can compete (in code optimization as an example) to many commercial compilers.

Anyway, if one is used to M128, one probably will find many differences when jumping to any ARM, while switching to M1281 is pretty straight forward. Even Xmega's are more similar to AVR than to ARM, but many goodies are more or less similar (DMA, pointer based peripherals, advanced HW support, many similarities or similar approaches can be found between Xmegas and AT91SAM peripherals).

Guillem.
"Common sense is the least common of the senses" Anonymous.

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The AT90CAN128 family is fully pin compatible with the mega128, except for pin 1 PEN which became "do not connect". It is more expensive, so unless you need CAN its not worth using. Like the mega1281 (where pin 1 became OC0B-PG5) its special function register addresses were reorganized and the timer0 and timer2 names were swapped from what the mega128 used. Both of these had their special function register naming conventions updated to the newer generation scheme and some bits moved to other registers, so they are not 100 % source code compatible with the mega128.

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Hey, thanks a lot for all the suggestions everyone... I'm starting a brand new design & just wanted to use something with lots of features, RAM, & similar physical size to the M128... I'll read up on all of your suggestions... Thanks!

- James

p.s. So would the ATXMega128A1 be very different to figure out... programming-wise? I may want to go with the ATMega1281 if so...

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If you want familiarity then stick with the 1281 - the X128A1 is going to be QUITE different in the way the registers/bits are laid out.

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clawson wrote:
If you want familiarity then stick with the 1281 - the X128A1 is going to be QUITE different in the way the registers/bits are laid out.

It is true that the X128A1 is quite a bit different, but after working with this chip for a couple of weeks now I would highly recommend it. I worked with the M128 for several years now. The M1281 is a great way to go if you need a drop-in replacement for M128 with more ram and some more interrupt features. If you want a fresh new chip with lots of really cool features, then the X128A1 is a great next step forward. If you are developing code in C, it will not take you long at all to get up and running assuming you have a programmer that will work on your development platform. I have a fair sized application that I am porting from M128 to X128A1 right now and and pretty close to getting it done in a couple weeks of evening/weekend work. Haven't done too much with the analog portion yet other than playing with DAC for audio output, but looks like the main thing there is to remember to put some gain on your DAC output buffers so you can use the 1V internal reference and keep it linear due to silicon bugs for AREF larger than 2.4V. Also the ALE signal for external memory is inverted from what the datasheet shows.

If you look closely at all the features of the X128A1, you will see that there really isn't anything quite like it (even ARM solutions) and contrary to what some here will say, you can buy it from several vendors right now. I have puchased >100 from two vendors already.