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Larger EEprom — Parallax Forums

Larger EEprom

James LongJames Long Posts: 1,181
edited 2006-09-09 02:41 in Propeller 1
Ok....I know it has been posted here before....but I can't seem to find it.

Is it possible to use a larger EEprom with the propeller?

Can I use a larger Eeprom for the basic memory storage...or can I only use it for expanded storage of information?

Please realise...I do not have my prop yet (it's in the mail) so break it down to simple terms for me.

Thanks for all who answer,

James L

Comments

  • Beau SchwabeBeau Schwabe Posts: 6,568
    edited 2006-09-08 20:08
    James Long,

    The largest memory that you can use without significantly altering the I2C addressing scheme (<--Read the Propeller will still be able to load it's Boot RAM from the same Memory IC) is a 24AA512.

    This will give you an additional 32K of upper scratch pad memory that the Propeller IDE doesn't touch, but you can access it from within your Propeller program. The Propeller program
    will reside in the lower 32K of memory.

    Of course there are no memory limits if you use an additional EEPROM device.

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    Beau Schwabe

    IC Layout Engineer
    Parallax, Inc.
  • James LongJames Long Posts: 1,181
    edited 2006-09-08 20:33
    Beau said...
    The largest memory that you can use without significantly altering the I2C addressing scheme (<--Read the Propeller will still be able to load it's Boot RAM from the same Memory IC) is a 24AA512.

    This will give you an additional 32K of upper scratch pad memory that the Propeller IDE doesn't touch, but you can access it from within your Propeller program. The Propeller program
    will reside in the lower 32K of memory.

    Of course there are no memory limits if you use an additional EEPROM device.
    Thanks, that is just the answer I needed.

    James L
  • Mike GreenMike Green Posts: 23,101
    edited 2006-09-08 20:36
    There is a larger EEPROM that could be used. Atmel makes the AT24C1024 which is a 3.3V I2C 128K byte EEPROM which should just "drop-in" in place of the existing 24AA256. It's available in both a PDIP and SOIC package. Microchip also makes a 128K byte EEPROM, the 24LC1025 which also should just "drop-in". The Microchip version provides two separate 64K non-contiguous "pages" while the Atmel version provides a contiguous 128K address space so the chips are not interchangable. As far as the Propeller is concerned, this doesn't matter.
  • Beau SchwabeBeau Schwabe Posts: 6,568
    edited 2006-09-08 21:14
    Mike,

    True, and I suppose you could use an even larger EEPROM that "snuck" a bit or two into the Control register.

    James,

    You just need to study the datasheet and see how the I2C device is addressed, and it needs to stay compatible with the 24AA256 currently used.

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    Beau Schwabe

    IC Layout Engineer
    Parallax, Inc.
  • Mike GreenMike Green Posts: 23,101
    edited 2006-09-08 21:25
    Beau,
    I have yet to find a larger I2C EEPROM on the market. I'm sure they will be there eventually. I have not actually used the Atmel devices with the Propeller. I have a PropStick and a Propeller Robot Controller yet to be assembled and some sample Atmel devices that will go in them.
    Mike
  • James LongJames Long Posts: 1,181
    edited 2006-09-09 00:42
    Ok...so as I read it...the size is not the determining factor.....but the interface (communication) requirements are.



    Thanks for the views and answers,

    James L
  • Beau SchwabeBeau Schwabe Posts: 6,568
    edited 2006-09-09 02:41
    James,

    That's Correct

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    Beau Schwabe

    IC Layout Engineer
    Parallax, Inc.
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