How do you select the right processor?

Hi Ghamble,

I don't believe in choosing the 'right' component, but the solution should be a near optimum. I for once, are very pleased with the range of products of Microchip and stick with those devices as my knowlegde base is ten times more valuable than let's say the price of processor X from company Y.  So far, Microchip did not dissapoint me and i love their support and easy parts acces. Sometimes i get sampels for free, also demo boards and lot's of products are available at Farnell. Maybe more important is the wide spread knowlegde database on PICmicro around the globe and people who are willing to share their knowlegde. This is not possible in an corporate invironment, because of competition aspects.

Best regards,

Enrico Migchels

Power Supply Design Engineer

Heliox B.V.

Best - The Netherlands

www.heliox.nl

Hi all,

I'm new to the group, but not new to processors or processor selection.  My experience has been as the hardware guy that has to "implement" the processor that gets chosen...usually by committee, and then support it in production!  I think I like Ghamble's idea of a "wiki" document, and so I'd like to try and summarize Michaels (obviously very knowledgeable) comments above:

1) Make a list of "must haves"...this list should be complete enough to tell you if any particular processor is suitable.

2) Consider the cost...of the project and of prospective processors with respect to it.

3) Look at the intended life span of the product...will the selected processor be available that long?

4) Try not to plan to change parts between development and manufacture...It's just asking for surprises.

Personally my preference is to place significant emphasis on the life span issues, as I've had several designs "bitten" by discontinued processors.  It is quite common in electronics that a particular part gets discontinued, but in the case of a processor it can be a product killer...and very disappointing.

I have converted this "summary" and expanded the commentary some in the "documents" section, here:

http://www.element-14.com/community/docs/DOC-21182

I think that is what someone suggested...:-)

-Dave

I agree with what has been said.

I would add is that the culture and history has a major

influence regarding what is "right".

If a lab uses a uC from a given vendor they will tend to stay

with that vendor and toolchain if posssible.  You can burn

a lot of engineering time learning new toolchains.

Hi Everyone,

Thanks, but please remember: I only summarized Michael's response. This is not "my" document...I've gone ahead and tried to incorporate Dan's suggestion because I think he's right, tools are pretty important.  But I'd like to suggest that rather than me paraphrase what they say, a better way is if Dan and Michael add to the document themselves...

Maybe it's more like a bunch of chefs "cooking up" a recipe than a doctor curing cancer.  I can help write down "Michael's recipe", but there's some other "ingredients" Dan might use a little more or less of, or he might even mix things up differently...there's really not one right way, and Michael and Dan can each communicate their own way of doing it much better than I can tell you how they do it...

In fact, perhaps what's needed here is just to encourage Everyone to go ahead and feel free to pitch in and edit too.  If you see some "ingredients" of selecting a processor we maybe haven't sprinkled in yet, just toss 'em on in the "pot"!  That's the "wiki" part.  I'll trust Ghamble to correct me if I'm mistaken here, but everyone at E-14 gets  an edit button for this document when they're logged in...right?

So please, don't worry in the least about "my" document or "his" recipe, just keep throwing stuff in to suit your own taste (perhaps being careful we don't make it too "salty" )  If it doesn't "taste right" afterward, things can easily be taken back out of the "mix" again...I guess maybe the analogy actually falls apart there.  But, when a bunch of cooks all agree on "add a pinch of this" or "it's done when it looks like thus-and-so" it's usually a pretty safe bet folks will like what ends up on their plate...

Hey Dave,

Yeah, I like your document. But sometimes also engineers' experience is also included in the checklist, and also whether we have already say a programmer or debugger from a certain manufacturer.

-Erya-