Batteries dieing and memory loss

I am developing with a Dell Axim X5. When it is left on the shelf for more
than two weeks the main battery goes dead, the back-up goes dead, and all
RAM based memory in the device is lost.

I can see my main battery going dead because, from what I understand, is
that Windows is waking up the PDA a few times a day for house keeping. But
when the back-up goes dead and the memory is lost it really sucks. You have
to go and buy a new coin battery and re-install all the software, not to
mention all the information that was lost. Not a very functional back-up
system and a very poor design I might add.

I guess my question is, is this a Dell thing or a Pocket PC thing? Windows
CE? Is there a software patch that will fix this? Is this the same on all
Pocket PCs?

Thanks
Thomas

Chris
Thu Jul 08 12:14:14 CDT 2004

It's a Pocket PC thing. Data is stored in RAM. When power is lost, the RAM
is no longer refreshed, and all data is lost. The "workaround" is to store
the data to persistent media like Flash, but there are other problems
associated with that that make persisting an app very difficult. SOme PPCs
allow you to back up the object store (contacts, etc) to flash, but
generally speaking that's just how embedded devices work.

--
Chris Tacke, eMVP
Co-Founder and Advisory Board Member
www.OpenNETCF.org
---
---
Principal Partner
OpenNETCF Consulting
www.OpenNETCF.com



"Thomas Magma" <somewhere@overtherainbow.com> wrote in message
news:ux8t3zQZEHA.4032@TK2MSFTNGP11.phx.gbl...
> I am developing with a Dell Axim X5. When it is left on the shelf for more
> than two weeks the main battery goes dead, the back-up goes dead, and all
> RAM based memory in the device is lost.
>
> I can see my main battery going dead because, from what I understand, is
> that Windows is waking up the PDA a few times a day for house keeping. But
> when the back-up goes dead and the memory is lost it really sucks. You
have
> to go and buy a new coin battery and re-install all the software, not to
> mention all the information that was lost. Not a very functional back-up
> system and a very poor design I might add.
>
> I guess my question is, is this a Dell thing or a Pocket PC thing? Windows
> CE? Is there a software patch that will fix this? Is this the same on all
> Pocket PCs?
>
> Thanks
> Thomas
>
>
>

somewhere
Thu Jul 08 12:47:33 CDT 2004

Hi Chris

It's not how my 15 year old TI-85 calculator works. When the main
batteries die the device stops functioning but the back-up battery
maintains the RAM for years. Seems like a simple concept to me.

Thomas


Chris Tacke, eMVP wrote:

> It's a Pocket PC thing. Data is stored in RAM. When power is lost, the RAM
> is no longer refreshed, and all data is lost. The "workaround" is to store
> the data to persistent media like Flash, but there are other problems
> associated with that that make persisting an app very difficult. SOme PPCs
> allow you to back up the object store (contacts, etc) to flash, but
> generally speaking that's just how embedded devices work.

Chris
Thu Jul 08 13:01:18 CDT 2004

The architecture is significantly different. Put 64MB DRAM in the TI and
see how long it lasts. My motorycycle gets way better mileage that my
minivan, but I'd hate to take a family vacation on it.

--
Chris Tacke, eMVP
Co-Founder and Advisory Board Member
www.OpenNETCF.org
---
---
Principal Partner
OpenNETCF Consulting
www.OpenNETCF.com



"Thomas Magma" <somewhere@overtherainbow.com> wrote in message
news:OAdqmORZEHA.1508@TK2MSFTNGP09.phx.gbl...
> Hi Chris
>
> It's not how my 15 year old TI-85 calculator works. When the main
> batteries die the device stops functioning but the back-up battery
> maintains the RAM for years. Seems like a simple concept to me.
>
> Thomas
>
>
> Chris Tacke, eMVP wrote:
>
> > It's a Pocket PC thing. Data is stored in RAM. When power is lost, the
RAM
> > is no longer refreshed, and all data is lost. The "workaround" is to
store
> > the data to persistent media like Flash, but there are other problems
> > associated with that that make persisting an app very difficult. SOme
PPCs
> > allow you to back up the object store (contacts, etc) to flash, but
> > generally speaking that's just how embedded devices work.
>
>
>

somewhere
Thu Jul 08 14:03:53 CDT 2004

The Micron MT48H4M16LF 64MB DRAM has a standby refresh current of 100 uA.
The Energizer CR2032 coin battery has a capacity of 220 mA/hr. This should
result in a DRAM memory retention of over 3 months from the coin battery
itself not to mention the 1440 mA/hr main battery.

Are the designers of these devices just getting lazy?


Chris Tacke, eMVP wrote:

> The architecture is significantly different. Put 64MB DRAM in the TI and
> see how long it lasts. My motorycycle gets way better mileage that my
> minivan, but I'd hate to take a family vacation on it.

Chris
Thu Jul 08 14:29:37 CDT 2004

I agree that 2 weeks seems pretty short, and it does seem like something
else seems to have been left on, not just the DRAM. Whether it's a floating
i/o, an amplifier or what it's hard to say and I agree that it probably
should have been looked at closer, but they probably assumed that it would
sit in a powered cradle when not in use. So yes, it's may be laziness,
though I don't know what kind of schedules they were up against either. I
wonder if they try to wake for alarms or anything even whne the main battery
is dead. That would kill the life pretty quickly, even if it went back to
sleep right away.

--
Chris Tacke, eMVP
Co-Founder and Advisory Board Member
www.OpenNETCF.org
---
---
Principal Partner
OpenNETCF Consulting
www.OpenNETCF.com



"Thomas Magma" <somewhere@overtherainbow.com> wrote in message
news:eWy%23Q5RZEHA.2340@TK2MSFTNGP09.phx.gbl...
> The Micron MT48H4M16LF 64MB DRAM has a standby refresh current of 100 uA.
> The Energizer CR2032 coin battery has a capacity of 220 mA/hr. This should
> result in a DRAM memory retention of over 3 months from the coin battery
> itself not to mention the 1440 mA/hr main battery.
>
> Are the designers of these devices just getting lazy?
>
>
> Chris Tacke, eMVP wrote:
>
> > The architecture is significantly different. Put 64MB DRAM in the TI
and
> > see how long it lasts. My motorycycle gets way better mileage that my
> > minivan, but I'd hate to take a family vacation on it.
>
>
>

somewhere
Thu Jul 08 17:03:12 CDT 2004


I read somewhere on another site that once the main battery is dead you
only have about 72 hours before the back-up battery fails. So you are
right to assume that there are other processes involved that is using up
current other than the SDRAM.

I can only hope that these issues will be dealt with sometime in the near
future.

Chris Tacke, eMVP wrote:

> I agree that 2 weeks seems pretty short, and it does seem like something
> else seems to have been left on, not just the DRAM. Whether it's a floating
> i/o, an amplifier or what it's hard to say and I agree that it probably
> should have been looked at closer, but they probably assumed that it would
> sit in a powered cradle when not in use. So yes, it's may be laziness,
> though I don't know what kind of schedules they were up against either. I
> wonder if they try to wake for alarms or anything even whne the main battery
> is dead. That would kill the life pretty quickly, even if it went back to
> sleep right away.

Bruce
Thu Jul 08 18:01:15 CDT 2004

Keep in mind that the PPC also has CPU, which is using minimal power also.
There may also be some other peripherals which need to stay powered to
provide you with certain functionality.

Currently, the requirement for the backup battery is only about 48 hours,
just long enough for you to get back to the office on Monday and plug it in.

I know many of the engineers that you are questioning, both at Microsoft and
the OEMs, let me assure you that they are not lazy and that they take this
very seriously. The OEMs spend considerable amount of time and effort both
optimizing the hardware and software for power consumption. Both Microsoft
and the OEMs are looking at ways to optimize for both power consumption,
features and price, this is a difficult juggling act.

I think that we would all agree that as far a power consumption and
persistent store it isn't quite there yet. I would expect that this will
change in the future.

One of the problems, which is the one that you are experiencing, is that the
PPC has no way to know that you have stopped using it and more importantly
won't be using it for many days or weeks. If it did, then it could go into
a "no longer being used as a PDA" mode and shut down even more, like
presenting your reminders.

--
Bruce Eitman (eMVP)
Senior Engineer

Thomas
Fri Jul 09 09:21:08 CDT 2004

I shouldn't have used the term "lazy". I know what its like to be under the
gun. I just don't think there was enough time dedicated towards memory
retention.

I believe your right about back ground processes of the CPU, the device is
waking up at midnight to do housekeeping which requires at least one
watchdog timer. But to continue to do this and flatten both your main and
your back-up battery is silly. Wouldn't a more logical strategy be to run
the unit normally until the main battery got down to a certain voltage, then
shut off all that housekeeping crap except for the RTC (real time clock) and
dedicate the rest of the main battery to memory retention. Then as a last
resort switch over to the back-up. This should be easy to do since DRAM runs
at 1.8V and the main battery is 3.7V.

> Currently, the requirement for the backup battery is only about 48 hours,
> just long enough for you to get back to the office on Monday and plug it
in.

Where did this requirement come from? It's certainly not a requirement of
our company and our customer base.

Thomas



"Bruce Eitman (eMVP)" <beitmannospam@nospam.neo.rr.com> wrote in message
news:eIyy59TZEHA.644@tk2msftngp13.phx.gbl...
> Keep in mind that the PPC also has CPU, which is using minimal power also.
> There may also be some other peripherals which need to stay powered to
> provide you with certain functionality.
>
> Currently, the requirement for the backup battery is only about 48 hours,
> just long enough for you to get back to the office on Monday and plug it
in.
>
> I know many of the engineers that you are questioning, both at Microsoft
and
> the OEMs, let me assure you that they are not lazy and that they take this
> very seriously. The OEMs spend considerable amount of time and effort
both
> optimizing the hardware and software for power consumption. Both
Microsoft
> and the OEMs are looking at ways to optimize for both power consumption,
> features and price, this is a difficult juggling act.
>
> I think that we would all agree that as far a power consumption and
> persistent store it isn't quite there yet. I would expect that this will
> change in the future.
>
> One of the problems, which is the one that you are experiencing, is that
the
> PPC has no way to know that you have stopped using it and more importantly
> won't be using it for many days or weeks. If it did, then it could go
into
> a "no longer being used as a PDA" mode and shut down even more, like
> presenting your reminders.
>
> --
> Bruce Eitman (eMVP)
> Senior Engineer
>
>
>

Thomas
Fri Jul 09 09:58:09 CDT 2004

Or how about using a programmable RTC (real time clock) to wake up the CPU
when housekeeping duties are required. Typical RTCs have multiple interrupt
pins and draw 0.5 uA or less.

"Thomas Magma" <somewhere@overtherainbow.com> wrote in message
news:%23V7L2$bZEHA.3016@tk2msftngp13.phx.gbl...
> I shouldn't have used the term "lazy". I know what its like to be under
the
> gun. I just don't think there was enough time dedicated towards memory
> retention.
>
> I believe your right about back ground processes of the CPU, the device is
> waking up at midnight to do housekeeping which requires at least one
> watchdog timer. But to continue to do this and flatten both your main and
> your back-up battery is silly. Wouldn't a more logical strategy be to run
> the unit normally until the main battery got down to a certain voltage,
then
> shut off all that housekeeping crap except for the RTC (real time clock)
and
> dedicate the rest of the main battery to memory retention. Then as a last
> resort switch over to the back-up. This should be easy to do since DRAM
runs
> at 1.8V and the main battery is 3.7V.
>
> > Currently, the requirement for the backup battery is only about 48
hours,
> > just long enough for you to get back to the office on Monday and plug it
> in.
>
> Where did this requirement come from? It's certainly not a requirement of
> our company and our customer base.
>
> Thomas
>
>
>
> "Bruce Eitman (eMVP)" <beitmannospam@nospam.neo.rr.com> wrote in message
> news:eIyy59TZEHA.644@tk2msftngp13.phx.gbl...
> > Keep in mind that the PPC also has CPU, which is using minimal power
also.
> > There may also be some other peripherals which need to stay powered to
> > provide you with certain functionality.
> >
> > Currently, the requirement for the backup battery is only about 48
hours,
> > just long enough for you to get back to the office on Monday and plug it
> in.
> >
> > I know many of the engineers that you are questioning, both at Microsoft
> and
> > the OEMs, let me assure you that they are not lazy and that they take
this
> > very seriously. The OEMs spend considerable amount of time and effort
> both
> > optimizing the hardware and software for power consumption. Both
> Microsoft
> > and the OEMs are looking at ways to optimize for both power consumption,
> > features and price, this is a difficult juggling act.
> >
> > I think that we would all agree that as far a power consumption and
> > persistent store it isn't quite there yet. I would expect that this
will
> > change in the future.
> >
> > One of the problems, which is the one that you are experiencing, is that
> the
> > PPC has no way to know that you have stopped using it and more
importantly
> > won't be using it for many days or weeks. If it did, then it could go
> into
> > a "no longer being used as a PDA" mode and shut down even more, like
> > presenting your reminders.
> >
> > --
> > Bruce Eitman (eMVP)
> > Senior Engineer
> >
> >
> >
>
>

Bruce
Fri Jul 09 13:48:18 CDT 2004

I did not take offense, what I wanted you to know is that they do dedicate a
lot of time to power consumption thus memory retention. It is definitely
taken seriously.

I believe that the timer driven stuff does turn off when the backup battery
become the power source. But there is still a lot of drain on the battery
from hardware.

The requirement comes from Microsoft. It is part of the definition of what
a Pocket PC is.

--
Bruce Eitman (eMVP)
Senior Engineer

r_z_aret
Tue Jul 13 17:43:05 CDT 2004

On Thu, 08 Jul 2004 09:59:42 -0700, somewhere@overtherainbow.com
(Thomas Magma) wrote:

>I am developing with a Dell Axim X5. When it is left on the shelf for more
>than two weeks the main battery goes dead, the back-up goes dead, and all
>RAM based memory in the device is lost.

I have an industrial-type device that drains batteries in about 2-3
days. Sure is a bother. The good news is that this one also has a way
to install cab files in non-volatile memory, and set things up so a
hard reboot reinstalls them. It is not meant for end-users, but is not
too hard for a VAR to manage.

Devices with built-in wireless have a habit of leaving it on, and thus
draining the battery very quickly.


-----------------------------------------
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Robert E. Zaret, eMVP
PenFact, Inc.
500 Harrison Ave., Suite 3R
Boston, MA 02118
www.penfact.com