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64k... but spec shows 512k on the proto board? — Parallax Forums

64k... but spec shows 512k on the proto board?

TJHJTJHJ Posts: 243
edited 2008-08-18 22:23 in Propeller 1
So I was trying to source some of the 64k eprom's on the protoboard.

So according to the schematic www.parallax.com/Portals/0/Downloads/docs/prod/prop/Propeller-ProtoBoard-v1.2.pdf
it shows the eprom as a AT24C512

When I dig up the data sheet on this part I found this.

www.atmel.com/dyn/resources/prod_documents/doc1116.pdf from Atmel. According to this sheet this is a 512k eprom. ORganized into 64k blocks. Printed on the chip it says AT512 confirming that it is in fact the AT24C512.

Does this make any sense or am I having a special moment?

Also if I am seeking to retain my ability to store data into the upper 32k to survive a download should I use this chip or is there a better solution?

Thanks,
TJ

Comments

  • cheapskatecheapskate Posts: 6
    edited 2008-08-11 19:41
    Are you confusing bits and bytes, AT24C512 is a 512k bit device which equals 64k bytes.
    As far as I know and tried the propeller tool loads only the first 32k bytes to eeprom so data above this should not be touched.
    Reseting a propeller only reads the first 32k bytes from eeprom to hub memory, no writes to eeprom
  • parts-man73parts-man73 Posts: 830
    edited 2008-08-11 19:42
    That's 512k "Bits" not "bytes" it's 64K Bytes.

    The first 32K of the boot EEPROM is over written every time you program it with the Propeller Tool. The upper 32K is untouched, you can use that for whatever you like from within your own program.

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    Brian

    uController.com - home of SpinStudio - the modular Development system for the Propeller

    PropNIC - Add ethernet ability to your Propeller! PropJoy - Plug in a joystick and play some games!

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  • jazzedjazzed Posts: 11,803
    edited 2008-08-11 20:01
    I won't repeat the answer, but this does inspire a question, sorry if it's too OT.

    PropII is rumored to use 32K longs; what kind common I2C of device would provide that capacity? Looks like the biggest I2C variant parts are 128Kx8. Will it work to gang two I2C devices for boot? There are other serial interface type devices that are bigger. We may need new drivers.

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  • TJHJTJHJ Posts: 243
    edited 2008-08-11 21:26
    Doh, Thanks
  • hippyhippy Posts: 1,981
    edited 2008-08-12 00:10
    @ Jazzed : I keep wondering too, but no answers or hints from Chip or others yet.

    It's not just a capacity issue but a boot time issue; 256KB is 8 times bigger than 32KB but 8 times longer to boot isn't likely to be acceptable. I suspect there's some 'devious plan' but no word of what it is. There's some quite large SPI Eeprom around. I guess it'll either be that or, if it can be fast enough, SD Card.

    Has the Unofficial Expo got a secluded room nearby where Parallax staff can be taken, wined, dined and then have answers beaten out them smile.gif
  • Paul BakerPaul Baker Posts: 6,351
    edited 2008-08-18 21:55
    No beatings necessary (though maybe I should wear my "Beatings will continue until moral improves" shirt), some details about the next chip will be revealed at the NE expo. Chip found some chips that look like they'll fit the bill but some research on availibility will be needed before we make the plunge.

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    Paul Baker
    Propeller Applications Engineer

    Parallax, Inc.
  • BaggersBaggers Posts: 3,019
    edited 2008-08-18 22:23
    Don't forget to divulge the info to us none states side people, who unfortunately can't make it to the NE expo [noparse];)[/noparse]

    PS, OBC, has the stuff arrived yet? email, me, I have a few other questions [noparse];)[/noparse]

    Baggers.

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