Re: Flash retention in uC at higher temps, experience?

On Sun, 15 Jun 2008 02:11:10 GMT, Jonathan Kirwan
<jkirwan@xxxxxxxxxxxxxx> wrote:

On Sat, 14 Jun 2008 08:36:57 -0700, Joerg
<notthisjoergsch@xxxxxxxxxxxxxxxxxxxxx> wrote:

Jonathan Kirwan wrote:
On Fri, 13 Jun 2008 16:23:42 -0700, Joerg
<notthisjoergsch@xxxxxxxxxxxxxxxxxxxxx> wrote:

Jonathan Kirwan wrote:
On Fri, 13 Jun 2008 15:42:27 -0700, Joerg
<notthisjoergsch@xxxxxxxxxxxxxxxxxxxxx> wrote:

Hello All,

After some problems a client saw I was treated to my own dose of what is
likely flash loss: The uC in our mailbox door has become erratic. I
installed it about three months ago and half of the day it receives a
good pelting from the sun. First it began not recognizing some keys,
then it started doing weird stuff like lock cycling. Things it wasn't
meant to ever do. Batteries, contacts and such look ok, reset didn't
help, so that's not it.

TI has an app note about the topic:
http://focus.ti.com/lit/an/slaa392/slaa392.pdf

Figure 1 looks scary above the 80C range. Later they presented another
test with a different bake cycle which makes things look better but who
knows.

What is you experience with respect to flash errors on uC that are
exposed to elevated temperatures as most outdoors applications are?
I only have some small experience here with the MSP430. It seems to
operate at 140C at 3V and 3.3V for the several-hour long tests I've
done. But some bad experiences in storing data into the flash at that
temp and even at 3.3V and higher. But I didn't need the darn thing to
survive all that long, either.
Wow, problems within hours at 140C? Not cool :-(

No. No problems, at all. Just that I didn't run them for more than
about 5 hours at a time. Same one ran for weeks, though, at periodic
elevated temperatures. I was just collecting data from a rotating hot
surface and wanted to just stick the whole contraption there while it
stored a few bits of data into RAM. The battery was the problem.

However, you said "But some bad experiences in storing data into the
flash at that temp and even at 3.3V and higher."

Yes, I did. I gather you want to do that.

I haven't read, for understanding, the data *** you mentioned. I
just downloaded it, though, and thanks for pointing it up. I think it
wasn't around when I looked a few years back and I'm glad that you
pointed it up for me.

Your obvious solution is to move north about a thousand miles. ;)
My wife would absolutely not do that.

Oregon is absolutely beautiful! I've got pileated woodpeckers, 4
kinds of squirrels including a flying squirrel (nocturnal), peafowl,
chickens, guinea hens, turkeys and so on -- tall 60-80 year old firs,
two kinds of ferns, rhododendrons that bloom in succession around the
place, and it looks like a lush rain-forest national forest when you
walk the paths on the property. Lots of acres, 5000 sq ft home, 1/4
mile driveway to the house, view of the mountains, 5 minutes to a
hospital and 20 minutes to the PDX international airport, a 17 mile
well-maintained walking and horse trail that goes from 1/2 mile away
from my home to the Willamette River in Portland, and it cost me $330k
in 2002. Prices are still low, too. Next door has been on the block
for 2 years, is a million dollar home (tax appraisal price) with about
4500 sq ft and 5 acres, and is being offered at $599k now. I'm told
they'd accept under $500k. Neighbors are wonderful, too.

That sure sounds mouth-watering. But my wife likes places where there is
no winter (and now ours get colder every year ...) and I'd have a wee
problem with the property tax rates up there. 2% or more is IMHO
confiscatory. Oh, and I like proposition 13 (prop tax increase cap) in
California because I do not trust politicians enough to toss them the
keys to my bank account.

My place is appraised at $850k (down there, I know that is just a
shack but up here it's 5000 sq ft of quality, showy home and lots of
acres of prime hilltop land) and my property taxes are $4400/year.
Which is kind of high, I admit. It's the income taxes you'll probably
hate. It's a graduated rate, but I think the top rate (which applies
to most engineers, without even asking) is 9%. However, no sales tax.

3' of fantastic soils, 45" of rain a year nice and evenly distributed
all year 'round in a constant drizzle, and everything grows where you
throw the seed, no digging needed. What could be better? ;)

Ah, you shouldn't have written "drizzle", my wife would hate that kind
of weather.

I did that on purpose. I didn't want to make it seem too inviting.
Actually, I've come to appreciate the constant press of low clouds
overhead and the slippery feel of moist moss as you carefully walk
across your one year old, rotting wooden deck.

Jon
Ah, then you might consider moving down here, Jeorg! (and Jon would
no doubt KNOW that he was in hades... ;-) )

Today, it is only going to be about 115, but it is still early in the
summer. I have a view that is panoramic, going all the way from Palm
Springs to the south (I have a ridge to my direct south that blocks
the view somewhat) to Mount San Jacinto across the Banning Pass (and a
thousand wind turbines) to Mount San Gorgonio. In winter, it only
rarely hits freezing, and I can swim in my solar heated pool from
March to October. I do remember rain, and we actually had some this
year, maybe 2-3" or so during the winter...

Charlie
Edmondson Engineering
www.edmondsonengineering.com
.

Quantcast