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Please verify before I order a bunch.... 64K eeprom — Parallax Forums

Please verify before I order a bunch.... 64K eeprom

eagletalontimeagletalontim Posts: 1,399
edited 2014-04-23 06:21 in Propeller 1
I just want to verify that the 24LC64-I/P-ND eeprom on digikey is good to use with the Prop just like the 24LC256. I had a few 256K laying around and tested everything using those, but I really only need 64K (I store extra stuff in the upper 32K).

http://www.digikey.com/product-detail/en/24LC64-I%2FP/24LC64-I%2FP-ND/273427

Thanks!

Comments

  • Duane C. JohnsonDuane C. Johnson Posts: 955
    edited 2014-04-22 19:32
    So you are only needing 8K bytes, not the usual 32K bytes as in the usual 24LC256 part?

    Duane J
  • eagletalontimeagletalontim Posts: 1,399
    edited 2014-04-22 19:38
    I thought the Prop uses the lower 32K to store the "program"? Hence the need for a 64K eeprom since the upper 32K is not used by the "program" unless writing custom data for later use.
  • kwinnkwinn Posts: 8,697
    edited 2014-04-22 19:39
    That chip is only 64Kbits or 8K bytes vs 256Kbits or 32K bytes for the 24LC256. If you want 32K bytes of storage above the prop program you need a 24LC512.

    Gotta watch those specs. The manufacturers want to make their stuff sound as good as possible so they specify 64K bits because it sounds better than 8K Bytes. Sneaky bunch they are.
  • tonyp12tonyp12 Posts: 1,951
    edited 2014-04-22 19:39
    They are not 64 Kb, they are 64 Kbits.
  • JonnyMacJonnyMac Posts: 9,105
    edited 2014-04-22 19:39
    The part number for a 64K EEPROM is 24xx512.

    http://www.digikey.com/product-detail/en/24LC512-I%2FP/24LC512-I%2FP-ND/523018

    EEPROMs are specified in K bits. 512 x 1024 = 524,288 / 8 = 65,536 = 64K bytes.
  • eagletalontimeagletalontim Posts: 1,399
    edited 2014-04-22 19:42
    ahhh. Wow, I completely missed that. I guess the 24LC256 will work for me then.... It seems to work for me so far. Maybe the borrowed EEPROM storage code is storing different than I thought....
  • Duane DegnDuane Degn Posts: 10,588
    edited 2014-04-22 20:02
    eagletalontim wrote: »
    ahhh. Wow, I completely missed that. I guess the 24LC256 will work for me then.... It seems to work for me so far. Maybe the borrowed EEPROM storage code is storing different than I thought....

    If you're going to purchase a bunch of EEPROM I think you ought to seriously consider getting 64KByte chips and not 32KByte like the 24L256. Being able to store data in the upper EEPROM where it won't be erased when a new program is loaded is a huge plus. Not all my projects need to use the uppper 32K of the EEPROM but enough do that I never purchase 32KByte EEPROMs anymore.

    I know I'm not the only one around here who rarely (if ever) use 32KByte EEPROMs.
  • Peter JakackiPeter Jakacki Posts: 10,193
    edited 2014-04-22 20:35
    Use the 64K byte chips as you can pick them up cheap, I've used these ones here for under 70 cents @100 off.

    As mentioned the upper 32K (32kB) are useful if you don't want information etc erased when you do a program load. I'm not quite sure why you missed the bits vs bytes thing, maybe you were in a "bit" too much of a hurry :)
  • infoinfo Posts: 31
    edited 2014-04-22 21:36
    Yup, you did get bunch of valid answers. The 64Kbytes requires only one i2c address. You still have another 7 available i2c addresses, so using anything smaller than 64KB would be good only if you wanted to mass produce million gizmos and could save a buck on using smaller storage part.
  • Duane C. JohnsonDuane C. Johnson Posts: 955
    edited 2014-04-23 05:43
    I've not seen any examples using less than 32KByte memories.

    Now my question:
    Can smaller memories be used at all?
    I.e. will the Propeller Tool program them correctly?
    Just asking!

    Duane J
  • Peter JakackiPeter Jakacki Posts: 10,193
    edited 2014-04-23 06:09
    Duane C. Johnson wrote: »
    I've not seen any examples using less than 32KByte memories.

    Now my question:
    Can smaller memories be used at all?
    I.e. will the Propeller Tool program them correctly?
    Just asking!

    Duane J

    Just asking, eh? I'd think that the code would continually be overwritten when the addresses wrapped around plus it would fail on verify anyway. The other problem is the page write size which is 64 bytes for a 32K EEPROM but smaller devices have smaller page sizes too.

    Now seeing 64KB are to be had for less than 70 cents I wonder what right minded soul would ever endeavour to consider using anything smaller than 32KB. Sorry, what were you asking? :)
  • Duane C. JohnsonDuane C. Johnson Posts: 955
    edited 2014-04-23 06:21
    Hi Peter;
    Peter Jakacki wrote: »
    Just asking, eh? I'd think that the code would continually be overwritten when the addresses wrapped around plus it would fail on verify anyway. The other problem is the page write size which is 64 bytes for a 32K EEPROM but smaller devices have smaller page sizes too.

    Now seeing 64KB are to be had for less than 70 cents I wonder what right minded soul would ever endeavour to consider using anything smaller than 32KB. Sorry, what were you asking? :)
    That clarifies things nicely.
    Thanks.

    Duane J
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