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'[EE] Is it ok to use flash memory for data logger?'
2006\12\06@214435 by John Waters

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Hi All,

I'm designing a data logger that needs about 32K of RAM to store the acquired data. I'm thinking of using flash memory to replace the RAM, as this has the benefit that the user can switch off the power while the data will still retain. But my concern is, flash memory allows only a limited number of write operations while that for RAM is unlimited. As a data logger, there is always new data to write into the memory. Does it make sense to use flash memory for data storage in data logger?

Thanks in advance!

John

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2006\12\06@222822 by John Chung

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If you do intend to use the flash memory for
continuous writing try NOT do to it. There are a few
main reasons.

1) It is much harder to replace the MCU when the
memory
  goes bad instead of an external data eeprom chip
2) Cheaper to replace a data eeprom chip.
3) The memory in the MCU is very limited and not
enough
  for long duration of data logging. Use external
  memory.

Data in the flash or eeprom of the MCU should be used
for once in a while changes.

John

--- John Waters <spam_OUTjohn_fm_watersTakeThisOuTspamhotmail.com> wrote:

{Quote hidden}

_________________________________________________________________
> Enter the "Telus Mobility Xbox a Day" contest for
> your chance to WIN!  Telus
> Mobility is giving away an Microsoft Xbox® 360 every
> day from November 20 to
> December 31, 2006! Just download Windows Live (MSN)
> Messenger to your
> IM-capable TELUS mobile phone, and you could be a
> winner!  
> http://www.telusmobility.com/msnxbox/
>
> > -

2006\12\06@230716 by Paul Hutchinson

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> -----Original Message-----
> From: .....piclist-bouncesKILLspamspam@spam@mit.edu On Behalf Of John Waters
> Sent: Wednesday, December 06, 2006 9:45 PM
>
> Hi All,
>
> I'm designing a data logger that needs about 32K of RAM to store the
> acquired data. I'm thinking of using flash memory to replace the RAM, as
> this has the benefit that the user can switch off the power while
> the data
> will still retain. But my concern is, flash memory allows only a limited
> number of write operations while that for RAM is unlimited. As a data
> logger, there is always new data to write into the memory. Does it make
> sense to use flash memory for data storage in data logger?

I used I2C EEPROM in my last logger design because it has 100 times more
write life than flash. A single 24LC256 will give you 32Kbytes.

Paul

>
> Thanks in advance!
>
> John

2006\12\07@010920 by Bob Axtell

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John Waters wrote:
> Hi All,
>
> I'm designing a data logger that needs about 32K of RAM to store the
> acquired data. I'm thinking of using flash memory to replace the RAM,
> as this has the benefit that the user can switch off the power while
> the data will still retain. But my concern is, flash memory allows
> only a limited number of write operations while that for RAM is
> unlimited. As a data logger, there is always new data to write into
> the memory. Does it make sense to use flash memory for data storage in
> data logger?

Take a look  at RAMTRON devices. They have unlimited read/write cycles.
I have used them extensively, and have never seen one fail. They work
perfectly as a scratchpad, and they do NOT
have the flash "wait" delays or worries about the number of bytes in the
write queue. Write all the bytes you want, instantly.

Look at http://www.ramtron.com.  BTW: Mouser now handles these devices.

--Bob
{Quote hidden}

2006\12\13@031521 by tachyon 1

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I'm no expert in this area, but AFAIK, the write cycles of modern FLASH
is pretty high.
Probably higher than the liftime of your product. It is used in a lot of
high write applications.
It seems to me that a data logger would get a lot less writes to it than
a lot of USB keys.

 {Original Message removed}

2006\12\13@041844 by Peter Bindels

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If the logger is using the flash as a circular buffer most
disadvantages of flash disappear (flash seems to be adverse to write
hotspots as common in normal filesystems, but continual logging would
be pretty ok). Why not just include a battery though? Also, did you
consider FRAM?

On 13/12/06, tachyon_1spamKILLspamemail.com <.....tachyon_1KILLspamspam.....email.com> wrote:
>  I'm no expert in this area, but AFAIK, the write cycles of modern FLASH
> is pretty high.
> Probably higher than the liftime of your product. It is used in a lot of
> high write applications.
> It seems to me that a data logger would get a lot less writes to it than
> a lot of USB keys.
>
>  {Original Message removed}

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