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SPI SRAMs

Discussion in 'Electronic Components' started by Brendan Gillatt, Sep 16, 2007.

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    I have a fairly odd need here.
    Basically, I would like to extend the RAM of a PIC18F from 4KB to around
    20KB so that I can create some sortof framebuffer for a 130x130 lcd
    screen. Being simple chips, PICs can't address external RAM like, say,
    an 8051 can. I would like to keep the pincount down as _low_ as
    possible, with speed less of a priority. I was just wandering: is there
    such thing on the market as an SPI SRAM?

    If so is there anywhere that will supply to the UK in small volumes -
    <5? I've scoured the usual part suppliers - Farnell, Maplin, RS, Arrow
    and can't find any.

    If not I guess I'll just use another PIC as an SRAM controller set up as
    an SPI slave.

    - --
    Brendan Gillatt
    brendan {at} brendangillatt {dot} co {dot} uk
    http://www.brendangillatt.co.uk
    PGP Key: http://pgp.mit.edu:11371/pks/lookup?op=get&search=0xBACD7433
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  2. TT_Man

    TT_Man Guest

    Atmel do SPI based data flash, up to 64Mbits soic8 AT45DBxxx series. These
    will soon be available from Farnell....
     
  3. Chris Jones

    Chris Jones Guest

    Or you could go straight to an ARM-based chip which has the RAM in it.
    There are some from NXP with 32 and 64kB, though I have not used them.
    Farnell has a special offer on the non-RoHS version of the 32kB one
    (7342640), under £5. I have been trying the ADuC7020 series myself, but
    those have only 8kB SRAM I think.

    Chris
     
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    I was looking at the LPC2106 chips from NXP, I just don't really want to
    set up yet annother tool chain =]

    ARMs are definately on my to-learn list.

    - --
    Brendan Gillatt
    brendan {at} brendangillatt {dot} co {dot} uk
    http://www.brendangillatt.co.uk
    PGP Key: http://pgp.mit.edu:11371/pks/lookup?op=get&search=0xBACD7433
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    Ah, they look perfect if they'll read/write fast enough. Thanks for your
    reply.

    - --
    Brendan Gillatt
    brendan {at} brendangillatt {dot} co {dot} uk
    http://www.brendangillatt.co.uk
    PGP Key: http://pgp.mit.edu:11371/pks/lookup?op=get&search=0xBACD7433
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  6. Chris Jones

    Chris Jones Guest

    But it is still (mostly) flash, and so will wear out eventually.

    Chris
     
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