[Tinyos Core WG] Unit of time in TOS2

[David Gay]

On 10/20/06, Philip Levis <pal at cs.stanford.edu> wrote:
> On Oct 20, 2006, at 2:37 PM, Cory Sharp wrote:
>
> > On 10/20/06, Martin Leopold <leopold at diku.dk> wrote:
> > Hi All.
> >
> > Apart from this already making a WikiPedia standard - what is the
> > consensus - change the name or just update the documentation?
> >
> > Looking at the names again it seems that the units aren't the same
> > either. T32kHz implies 1/s and TMilli implies well ~ms. So it might
> > make
> > sense to keep the unit the same too.
> >
> > This is specified in the TEP,  "Note that the precision names are
> > expressed as either frequency or period, whichever is convenient."
> >
> > I'd like for us to keep our eye on the ball -- and that is to clear
> > naming confusion.  As far as I know, no user has ever been confused
> > as a result of period vs frequency naming differences.
> >
> > And what about 32kHz - is it implicitly clear that this is 32768 Hz?
> >
> > Probably.  With the previous comment about clearing confusion,
> > Milli vs Milbi is because milliseconds are common and confusion
> > does in fact happen once or twice a year.  I don't know that 32000
> > Hz is or ever will be prevalent.  Other naming options are T32768Hz
> > or T30p5us, etc.  They all look pretty gross to me.
> >
> > Going too far down this road is where I start to switch from being
> > indifferent on TMilbi to preferring the status quo of TMilli and
> > T32khz.
> >
>
> I dunno. The Milbi thing is neat and all, but I think all it's going
> to do is make readers go "Huh?" Martin's concern (correct me if I'm
> wrong) came mostly from measurement, in particular for scientific
> work. The same issues arise in all other system measurements, e.g.,
> megabytes, gigabytes, etc., yet the community hasn't collapsed.
>
> I think that keeping it as TMilli and T32khz is the right thing to
> do. We should mention milbi in the documentation, TMilbi,
> particularly when we get to 32khz, seems more trouble than it's worth.

One comment: the introduction has a paragraph about accuracy which
explicitly says that the timers may not be super accurate (i.e., that
1/1024s might well be 1/1000s anyway, the 1/32768s is definitely
something else on mica family platforms). So worrying too much about
the names doesn't seem that useful to me...

Which does possibly bring up the question of whether we want to
mandate better accuracy for TMilli... (but probably also a whole can
of worms about drift, crystal accuracy, etc, that we may not care
about...)

David