I recently had a question marked as off topic about what the smallest microcontrollers are. I get that people are probably looking at it as "a shopping or buying recommendation". However, this (and numerous other questions like it) get plenty of votes and views, so they are clearly serving a need and are pretty well received. So this got me to thinking...

I didn't really mean to ask about a specific recommendation, as in "buy XYZ part from ABC company for your application". I can look up datasheets just fine, if I know what type of thing I'm looking for. I wanted to have some idea of what the approximate state of the art is, and any important issues that one needs to be aware of related to that. A perfect answer may be something like "the smallest microcontrollers use bare die packaging but need to be wire-bonded, here are some examples... slightly larger parts are available in WLCSP BGA and tend to be around 2 x 2 mm but have small pitch which requires microvias... etc etc". Specific parts are only in there as examples. Whether this came across as a "shopping recommendation" it certainly wasn't intended in that spirit.

Examples of very informative answers which are not recommending a specific part in response to a question worded as a buying recommendation question:

What are the cheapest microcontrollers? "If you want rather more than 1000 then people like Microchip have special untested supply lines where you are responsible for ensuring devices are in spec and you get accordingly low prices. "

What are some smallest, cheapest microcontrollers with USB built in? "V-USB project provides needed software for bitbanged USB and is available under GPLv2 or commercial licenses."

Which low power microcontroller for short active periods at long intervals? "I found that it was best to have 2 batteries in series to squeeze every last mAHr out of the batteries."

The meta question then is: How to ask good (useful) questions of this type? Can we reconsider whether they are on-topic, and in what cases could they be on topic?

  • \$\begingroup\$ You can think of EE.SE like a library of questions, the questions last forever and are searchable by google. Because of this sites on SE are designed to give specific answers to specific questions. If you poke around the help center you can find the guidelines on questions and answers. These guidelines are put in place to not only serve people who what their questions answered but to preserve EE.SE as a reputable source of knowledge on the internet. There are plenty of other sites\fourms out there on the internet where you can discuss things if you desire. \$\endgroup\$
    – Voltage Spike Mod
    Aug 8, 2016 at 18:56
  • \$\begingroup\$ @laptop2d: You don't think the answers to the questions I gave as examples are valuable? Now, the example questions may be pretty weak, and answering them directly with "part X" wouldn't be valuable, but what people did answer is gold. I think there is an element of serendipity, the second question the asker almost certainly didn't know enough to ask "how do I do USB on a microcontroller that doesn't have hardware support for it?" - but the answerer did answer that, because it was relevant, even though it wasn't the question. \$\endgroup\$
    – Alex I
    Aug 9, 2016 at 16:37
  • \$\begingroup\$ Its not that they don't contain useful information, but not in the context of EE.SE and the guidelines the community and SE has decided upon here: electronics.stackexchange.com/help/on-topic and here: electronics.stackexchange.com/help/how-to-ask When I come to EE.SE, I check my own ways of doing things at the door and try and do what is best for the community and EE.SE. I also try to look into the reasons of why they do things they way they do, and it makes sense. It makes more sense the more you read up on how SE and EE.SE function. \$\endgroup\$
    – Voltage Spike Mod
    Aug 9, 2016 at 17:30
  • \$\begingroup\$ I think this blog post by Jeff Atwood adresses your question well. Its main point is that the problem with shopping questions is that they are outdated very fast, one should instead ask what qualities/specs etc. to look out for. \$\endgroup\$
    – caconyrn
    Aug 14, 2016 at 19:12

1 Answer 1


Those, simply, are not valuable questions. The answer can change at a moments notice, and due diligence on the part of the asker can make these better questions with a few hours work on their own.

"There are thousands of parts available, which is best for me?" -- which is what all three of your example questions boil down to -- really doesn't help you, and really doesn't help the community. First, you will get all sorts of opinion-based answers which reduce, in many cases to religion. Next, the whole scenario can change in a flash with a new release. Further, as any engineer will tell you, there are thousands of ways to skin a cat. Thousands of the parts you're trying to narrow down from will serve your purpose just fine, and you don't provide enough context to allow a serious responder to address the answer in your specific context.

Put the effort into reducing your own data set. Then, if you're still stuck, say something along the lines of:

I'm working on project X, and I have specific needs. I'm considering parts A,B, and C, for these specific reasons. I'm leaning toward B, because of these details in my specific scenario. Does anybody with more experience see something I'm not considering which might influence my choice?

That still might not be the best question, but at least it supports directed discussion that the asker and the community can both benefit from.

  • \$\begingroup\$ that makes sense, but you are ignoring all the examples I gave. I think the examples show pretty well that people give really useful answers that don't consist of "use part X", even if the question is worded as "which part should I use?". I think in many of those cases, if the asker had really thought about it, they would ask not "which part" but some other issue related to that... which is what the answers address, even if the question didn't ask it. \$\endgroup\$
    – Alex I
    Aug 9, 2016 at 16:34
  • 2
    \$\begingroup\$ @AlexI -with respect, I don't think I ignored anything. To use one example, the answers for the low-power microcontroller from 2012 are fairly obsolete. Even the day they were posted, there were probably 15 or more answers which were just as suitable. There was some interesting talk about energy scavenging, but that was fortuitous. It would have certainly shown up in a question that asked the right question. The fact that the question and good answers don't quite align make it a tough hit on a search. The right approach is either to close, or to edit the question to make it better. \$\endgroup\$ Aug 9, 2016 at 16:49

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