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Which RAM for a small frame buffer (8KB) — Parallax Forums

Which RAM for a small frame buffer (8KB)

inakiinaki Posts: 262
edited 2005-12-08 23:46 in General Discussion
I need to add some RAM to a SX project.
The space I need is about 8KB. It is intended to be used as a 8KB frame buffer for a printer.
The CPU·would be·a SX48 although I would like also to work with a SX28.

In your opinion/experience which would be a suitable RAM to use ?
I would like·to take as few pins as possible.
Speed is not a concern here but the fastest the better. smilewinkgrin.gif

·

Comments

  • Paul BakerPaul Baker Posts: 6,351
    edited 2005-12-08 18:25
    Ramtron's FRAM.

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    ·1+1=10
  • Jon WilliamsJon Williams Posts: 6,491
    edited 2005-12-08 18:31
    Terry Hitt (Bean) is working on a project that uses a 32K RAM connected directly to an SX48 -- perhaps he'll share details.

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    Jon Williams
    Applications Engineer, Parallax
  • BeanBean Posts: 8,129
    edited 2005-12-08 18:45
    inaki,
    · Yeah I'm working on a project that uses the cypress CY62256 chip. But it requires 26 I/O pins. I'm using the SX48 clocked at 4Mhz (for low power). It's was pretty easy to use. It is 70nSec so at 4Mhz I just need use one·NOP delay to access it. You can get them from digikey for $3.40 each in a 28 Pin DIP http://www.digikey.com/scripts/DkSearch/dksus.dll?Detail?Ref=170619&Row=161333&Site=US

    · If your interested I can whip-up a schematic and code (SX/B) for you.

    Bean.

    ▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
    "SX-Video·Module" Now available from Parallax for only $28.95

    http://www.parallax.com/detail.asp?product_id=30012

    "SX-Video OSD module" Now available from Parallax for only·$49.95
    http://www.parallax.com/detail.asp?product_id=30015

    Product web site: www.sxvm.com

    Those that would give up freedom for security will have neither.


    Post Edited (Bean (Hitt Consulting)) : 12/8/2005 6:49:06 PM GMT
  • Paul BakerPaul Baker Posts: 6,351
    edited 2005-12-08 18:51
    The cypress memory is indeed very good, its cheap fast and large. I didn't mention them because they require so many pins, for 8K unmultiplexed addressing youll need: 8 data, 13 address, plus control (2-3 pins) for a total of 23-24 pins, by no means a "few pins" solution.

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    ·1+1=10
  • Chris SavageChris Savage Parallax Engineering Posts: 14,406
    edited 2005-12-08 19:15
    Terry,

    ·· Is that chip a 32K SRAM?· I recognize the 62256 from 32K SRAMs I used in the Z80 days an assume it's the same configuration.

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    Chris Savage
    Parallax Tech Support
    csavage@parallax.com
  • BeanBean Posts: 8,129
    edited 2005-12-08 19:16
    Paul,
    Your right about the ungodly number of pins required. I have no experience with the Ramtron parts, but one of these days I hope to experiment with them (plus they are non-volatile). I need to use a slow clock for power reasons so a serial ram would be a little slow for my project.


    Chris,
    Yup, it's static ram.

    Bean.

    ▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
    "SX-Video·Module" Now available from Parallax for only $28.95

    http://www.parallax.com/detail.asp?product_id=30012

    "SX-Video OSD module" Now available from Parallax for only·$49.95
    http://www.parallax.com/detail.asp?product_id=30015

    Product web site: www.sxvm.com

    Those that would give up freedom for security will have neither.


    Post Edited (Bean (Hitt Consulting)) : 12/8/2005 7:24:50 PM GMT
    SXB
    SXB
    cypress ram.SXB
    4K
  • Chris SavageChris Savage Parallax Engineering Posts: 14,406
    edited 2005-12-08 19:25
    Okay, yeah I checked the link and was verifying the configuration.

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    Chris Savage
    Parallax Tech Support
    csavage@parallax.com
  • Paul BakerPaul Baker Posts: 6,351
    edited 2005-12-08 19:55
    I got some samples of the 32K serial, and they were sending me the parallel 128K chip, but they neglected to write my apartment number on the address so it showed up as a delivery exception w/ FedEX, after the second delivery attempt FedEx called Ramtron who in turn instructed FedEx to destroy the package 2 hours before I went to go pick up the package! grrr. I don't know if I want to wait another 6+ months for a new sample with the chance they'll screw up my address again. PS the serial version is very nice. But I'll use NewarkInOne as my supplier because I am happy with thier service.

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    ·1+1=10

    Post Edited (Paul Baker) : 12/8/2005 7:59:59 PM GMT
  • inakiinaki Posts: 262
    edited 2005-12-08 21:07
    I think a serial solution would be better for my needs, 26 pins is too much.

    In the RAMTRON site there are two flavors of serial: serial 'two wires' and SPI.

    Then there are 2.8V, 3V an 5V, each with different packages.

    Paul, which one did you try with the SX ?
  • Paul BakerPaul Baker Posts: 6,351
    edited 2005-12-08 21:36
    FM25256 256Kb 8SOIC 15MHz 4.0V-5.5V SPI

    The FM25640 is the 8K (64Kb) version of the same chip (its bus speed is 5MHz)

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  • Chris SavageChris Savage Parallax Engineering Posts: 14,406
    edited 2005-12-08 23:37
    Paul,

    ·· You've probably posted this before, but what is the part number of the serial version of the 32K RAM chip you used/ordered?· Thanks.

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    Chris Savage
    Parallax Tech Support
    csavage@parallax.com
  • Paul BakerPaul Baker Posts: 6,351
    edited 2005-12-08 23:46
    ROFL thanks Chris you just made my day, its the first line of the post just before yours [noparse]:)[/noparse])) The 256 is the kilobits, or 32 kilobytes.

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    ·1+1=10

    Post Edited (Paul Baker) : 12/9/2005 1:49:04 PM GMT
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