Funny, Pascal, I'm not trying to justify myself, when I started out in
this industry there really was nobody with any experience to give
guidance. Sometimes I wish there had been, but then other times I'm glad
there wasn't. Now there are lots of places to go for help and advice so
to ignore it without consideration would be silly.

Yep, my responses are terse at times, and it takes an awful lot to
offend me. There are reasons why they might come across that way, but
they are always meant to try to push people along the route that my
experience suggests would be most productive. Luckily everybody has had
different experiences, which gives most posters plenty of choices to
select from.

Al

Hello!

> I don't necessarily use polling because I think it is easier as a first
> run, especially if I plan to ultimately use interrupts, that is just a
> waste of effort. [...] For example when Ti first took over Chipcon [...]

You don't have to justify yourself for using polling like if you
were caught with your hand in a box of biscuits. The fact is that you
(even you!!!) sometimes use this technique. And so do I.
And I don't consider it as a waste of effort, it's simply no effort at
all. Just a matter of calling a function written once and only once
for a given processor family, therefore good enough for experiments.

Anyway, you also started like this (when you "didn't know better").
I also started like this, and most programmers do. After all, I guess
most programmers learn how to make a loop before they learn how to deal
with interrupts.

> I don't post here for the applause, if I did I'd have left the
> group long ago, since most responses i get, usually off line, are
> aggressive and rude.

Without any intention to offend you at all, but with the tonality of some of your
replies or comments, I'm not surprised that some may feel hurt. This of course
does not justify to be rude or aggressive, but it can explain it. That said, you're
not alone in this case.

Pascal

Actually I thought my reply was on the lines of "why would you do this,
do you understand the dangers of it".

If you don't understand what you're doing then it is wise to avoid as
many pitfalls as you can, once you do understand then the dangers are
not great. When I was young and dumb I used polling because I didn't
know better, even though I understood the use of interrupts then. Now I
understand the difference between when it is safe to use it and when it
isn't. Sometimes there is simply no choice, such as with the early PIC
parts, which had no interrupts, but, even then there were ways to
protect against the failed condition. From his various posts the OP
doesn't, or didn't get it.

I don't necessarily use polling because I think it is easier as a first
run, especially if I plan to ultimately use interrupts, that is just a
waste of effort. I generally use it if I am trying a new function and am
not 100% clear about how a device might operate. For example when Ti
first took over Chipcon there was virtually no information available on
the CC1100. most of the Chipcon guys seemed to have left adnw ere not
disposed towards supporting Ti, and Ti themselves were pretty clueless
at the time. the amount of information available was minimal, sometimes
acontradictory, and always incomplete. Add to that the number of errata
associated with these early parts and life was going to be fun. So in
this case I developed my first run code using some polled loops and some
interrupts, this was done to allow me to develop a more complete
understanding of what was going on under the covers. Polling was used
more as a debugging tool.

It is not 'my method' vs 'your method'. I didn't invent any of these,
but I do know how to determine which of many methods is likely to be
safer, by analysing various failure modes, and who ever mentioned being
thanked? I don't post here for the applause, if I did I'd have left the
group long ago, since most responses i get, usually off line, are
aggressive and rude. I post here because I've enjoyed doing this since I
was 9 years old, over 50 years ago, and I still enjoy it, and would like
to pass on some of what I've learned over the years in the hope that it
might increase somebody elses enjoyment.

Al

Hello!

> I thought that the reason people posted questions here was to get advise
> from those with more experience then they have.

Indeed. There are many ways to reply:
- The "Your method is dumb, mine is smart" reply. Do what I say, I know what's good
for you, I know you'll thank me later etc...
- The straight to the point reply,

I notice that you allow yourself what you would like to ban for others:

> I didn't say I never used polling, but generally I keep it to the
> scenario you describe, ie developing a first run at a function.

What tells you that the original poster doesn't want a first run of some
experiment? I remember having used this method the first time I had to deal
with I2C, one eye on the debugger and the other on the oscilloscope, and I
also use polling for a first run because I think it's simpler to get something
working in an early development stage. And apparently you do also think it's
simpler, otherwise you wouldn't bother using polling at all, would you?
And if you know how to do, why not replying straight with warnings dictated
by your long experience?

Pascal

Okay gentlemen here is my further question please. If you interface the MSP430F5529 with an EEPEOM in interrupt mode how do you detect the acknowledge bit generated with EEPROM please?

Thanks,

John.

The needs of the many, outweigh the needs of the few,

.

.

.

Or the one

Sometimes you might actually have to shave off that 15uS, in which case
the 3 hours is worth it. Sometimes it may not be necessary, but if you
are selling 100k units and that 15uS saves a 0.1% on mean energy
consumption then it might also be worth it. At other times the energy
you burn in doing it outweighs any benefits, which was the point Paul
was making, and I agree, but, as with pauls comment on LEDs and Solar
panels.

LEDs are claimed to save 80% over incandescents, but in practice you can
reduce that to close to 95% very simply. Solar panels without energy
storage are only worth so much, but combine solar and wind, using
something like a compact VAWT, and you've opened up a whole new can of
worms that could redefine energy distribution for the next genration.
Let's face it the $10b or so in lost energy each year simply moving that
energy from the place it is generated to the place it is consumed is a
ludicrous outdated concept.

Sorry, whole new topic here, my apologies, but, if you haven't guessed
by now energy consumption is kind of a passion!.

Al

How do you measure ROI?

I spent 3 hours once shaving off 15 uS.

Was it worth it?

In my particular case, NO!!, but in a further combined team effort, YES.

> > Many designs do not care for power consumption. The fact the MSP430 is
> "designed for ULP" means nothing when it is acting as a USB peripheral
> with 500mA at its disposal.
> To me it does mean something. Even if I didn't have to use low power I
> would if I could. I once calculated that if the CPU in your PC used the
> same pricipals of low power operation as the MSP and other similar micros
> that the energy reduction globally would be equivalent to removing
> something like 16m vehicle from the road. I have 14 grandchildren, and I
> fear for their future

This only applies if the energy you save from device deployment is more than
the energy required to make that saving during development. For many
low-volume products, the extra engineering required to save more energy is
not recouped over the lifetime of the deployed devices. I have no idea how
you energy-reduce Windows, but at least Apple is having a bash with OS X.

But you know this. Case in point: LED bulbs and solar panels.

--
Paul Curtis, Rowley Associates Ltd http://www.rowley.co.uk
SolderCore Development Platform http://www.soldercore.com

Beginning Microcontrollers with the MSP430