
Why is my processor consuming more power than its datasheet suggests? - segfaultbuserr
https://www.analog.com/en/analog-dialogue/raqs/raq-issue-146.html
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flyinglizard
Reminds me of the development of a battery powered medical device I did about
7 years ago. We selected an esoteric Freescale microcontroller for that
project (which was successfully used in such applications before), but for the
life of me I couldn't get the power consumption in deep sleep to come anywhere
near the spec (few microamps IIRC).

Eventually, after scanning the datasheet forward and backward again and again,
I had this idea which turned out to be the right answer: microcontrollers
usually come in several package configurations, each with a different number
of pins. Freescale used the same silicon die in all of the variants of that
microcontroller, and left unrouted pins floating internally. I had to write to
registers which, on paper, didn't even exist on this processor variant to put
all I/Os in a defined state. The power consumption then came within the spec.

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beatgammit
We had a similar issue, but with date corruption instead of just excess power
usage. Always tie every input to something, don't just leave them unused.

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kazinator
TL;DR: if you don't treat unused pins according to the datasheet
recommendations, then all bets are off.

This is even true with lowly things like op-amps. If you have a dual op-amp
IC, and you use only one op-amp, you should do something appropriate with the
pins of the unused one.

[http://www.ti.com/lit/an/sboa204a/sboa204a.pdf](http://www.ti.com/lit/an/sboa204a/sboa204a.pdf)

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persistent
The Analog Dialog is a treasury of good advice going back decades. Really
worth your time if you have any interest at all in electronics.

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cr0sh
Better question - where did they get a datasheet?

Ok - I haven't read the article - maybe they're talking about some processor
where the manufacturer actually provides a datasheet. Most companies do. I
think even AMD does; I know you can get datasheets for the ARM
implementations, and most other embedded processors...

...but has anyone found any recent Intel processor datasheets (ok, maybe at
this point they'd be several volume databook libraries - but you know what I
mean)?

The last time I tried to find something recent from Intel, the most recent
datasheet of any kind I could find (one that listed technical stuff like
registers, pins, opcodes, etc - not just some basic figures and marketing
junk), I think the latest I found was for the Core2 Duo/Quad series - then
nothing after that?

Is there some secret trick to getting these? All I could figure at the time
was that you had to be part of some program or something, maybe with an NDA -
or an actual motherboard manufacturer or something? But then again, how would
you write a compiler without the information about opcodes and such?

Now honestly - I don't need such datasheets. But I wanted to look at something
"cutting edge" or relatively new (and really, the Core2 datasheet was good
enough for this) - and compare it with old datasheets for like the 6809 or
6502 or Z-80, old-school 8-bit processors (the ones I grew up with) - just to
see how things have changed (or haven't) and how "insane" things have gotten.

More like a lark for a laugh kind of thing that anything else.

It just struck me that I couldn't easily find them for recent Intel stuff...at
least, not easily on the web (but again, maybe I wasn't looking in the right
area, or there are other reasons at play).

~~~
anonymfus
_> Ok - I haven't read the article - maybe they're talking about some
processor where the manufacturer actually provides a datasheet._

You don't ever need to read the article, URI is enough to know the
manufacturer.

 _> The last time I tried to find something recent from Intel, the most recent
datasheet of any kind I could find (one that listed technical stuff like
registers, pins, opcodes, etc - not just some basic figures and marketing
junk), I think the latest I found was for the Core2 Duo/Quad series - then
nothing after that_

That was the last generation supported by non-Intel chipsets. It is not a
coincidence.

