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

On Sat, 14 Jun 2008 08:36:57 -0700, Joerg
<notthisjoergsch@[EMAIL PROTECTED]
> wrote:

>Jonathan Kirwan wrote:
>> On Fri, 13 Jun 2008 16:23:42 -0700, Joerg
>> <notthisjoergsch@[EMAIL PROTECTED]
> wrote:
>> 
>>> Jonathan Kirwan wrote:
>>>> On Fri, 13 Jun 2008 15:42:27 -0700, Joerg
>>>> <notthisjoergsch@[EMAIL PROTECTED]
> 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 sheet 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 air****t, a 17 mile
>> well-maintained walking and horse trail that goes from 1/2 mile away
>> from my home to the Willamette River in ****tland, 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