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Quick EEPROM question — Parallax Forums

Quick EEPROM question

W9GFOW9GFO Posts: 4,010
edited 2009-06-22 15:29 in Propeller 1
Does writing the exact same value to the same address in EEPROM affect how many times you can write to it before it becomes unreliable?

Rich H

Comments

  • Mike GreenMike Green Posts: 23,101
    edited 2009-06-22 00:02
    Yes

    It's common practice to read a location in EEPROM before modifying it so there's a write cycle only when the value changes.

    READ location,contents
    IF newContents <> contents THEN
    WRITE location,newContents
    ENDIF
  • W9GFOW9GFO Posts: 4,010
    edited 2009-06-22 00:46
    Thanks Mike

    Rich H
  • MagIO2MagIO2 Posts: 2,243
    edited 2009-06-22 03:27
    Isn't it even worse? I thought EEPROMs are deleting the whole page. So, even if you only write back one byte, the whole page is rewritten.

    Or do I mix this up with flash memory?
  • Mike HuseltonMike Huselton Posts: 746
    edited 2009-06-22 05:34
    That is the reason I use Ramtron FRAMs. A small extra expense for peace of mind.

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    JMH
  • mctriviamctrivia Posts: 3,772
    edited 2009-06-22 06:38
    the eeprom i use on the propmod are rated to 1M writes. Unless you are writing a lot to them wearing out is not a problem. Will last 10 years if you keep it under 273 writes a day.

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    propmod_us and propmod_1x1 are temporarily out of stock(selling faster then expected). Only $30. PCB available for $5

    Need to upload large images or movies for use in the forum. you can do so at uploader.propmodule.com for free.
  • MagIO2MagIO2 Posts: 2,243
    edited 2009-06-22 07:16
    Yep .. I use the Ramtrons as well.
    What driver do you use? The basic i2c seems to be a bit slow. Is there a driver which can read/write at max. speed of a Ramtron?

    Doesn't one write to an EEPROM count as 2 write cycles? First it has to be cleared, then the data is written. Plus .. the given number of write cycles is an average. I remember a AVR microcontroller that I used, which had a broken flash after a few month of development. Number of write cycles by far not reached.

    Post Edited (MagIO2) : 6/22/2009 7:23:36 AM GMT
  • HollyMinkowskiHollyMinkowski Posts: 1,398
    edited 2009-06-22 14:04
    @James Michael Huselton

    I went to the manufacturer's page to read up about those frams you mentioned. They claim
    "High Endurance 100 Trillion (1e14) Read/Writes".

    That is really superior to eeprom!
    Gonna call them and see if I can beg a sample or two.
    Thanks for mentioning them smile.gif
  • Mike HuseltonMike Huselton Posts: 746
    edited 2009-06-22 14:14
    Holly,

    They sent me samples 6 months ago for all of their FRAMS.
    If they give you trouble, send me an Instant Message or PM, as it is called. I have oodles of samples and carrier (adapter) boards.

    ▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
    JMH
  • HollyMinkowskiHollyMinkowski Posts: 1,398
    edited 2009-06-22 14:19
    @James Michael Huselton

    Thanks!
    If I can't get any samples I will PM you and you could send them to my house or where I work smile.gif
  • KyeKye Posts: 2,200
    edited 2009-06-22 14:24
    Where do you actually buy their products however? I couldn't find their stuff in stores like digikey.

    Maybe it was just one of the products I was looking for...

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    Nyamekye,
  • Mike HuseltonMike Huselton Posts: 746
    edited 2009-06-22 15:29
    Kye,

    Arrow Electronics is the distributor. Try www.findchips.com.

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    JMH
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