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memory mapping on eeprom — Parallax Forums

memory mapping on eeprom

mosquito56mosquito56 Posts: 387
edited 2009-06-11 14:28 in Propeller 1
· I have been cruising the site and found the idea of using the upper 32k of the eeprom for storage.·I would like to store my setting on·the eeprom but have no way to tell where the upper 32k starts. I looked for the chip on the protoboard at the parallax site but it just says 64k eeprom. The chip is so small I can't read what it is. How do I find the starting point of the upper 32k of the chip?
· I have searched the site but get so many returns I don't know what to search for.

The post "help writing spin code to propellor" was very helpful.
Don

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Comments

  • Peter JakackiPeter Jakacki Posts: 10,193
    edited 2009-06-10 22:17
    Don, does "upper 32k" not ring a bell mate? [noparse]:)[/noparse]

    Last time I checked 32kB in hex is $0000..$7FFF so the "upper" 32k of a 64k chip must be $8000..$FFFF or am I missing your point? If you are not sure whether it's a 32k or 64k then just read the first few locations at $8000 as they should be blank or different from those at $0000. If they are the same then the EEPROM is a 32k chip which ignores the msb of the address.

    *Peter*
  • Mike GreenMike Green Posts: 23,101
    edited 2009-06-10 22:18
    The boot EEPROM area is locations $0000 through $7FFF. The 64K EEPROM on the Protoboard supplies locations $0000 through $FFFF. That leaves locations $8000 through $FFFF that are completely available for the programmer to use.
  • mosquito56mosquito56 Posts: 387
    edited 2009-06-11 05:41
    Thanx Mike, I had an idea that might be the case but didn't want to take the chance of frying my eeprom. The simple i2c looks like it would work the same as fsrw. Also, I just couldn't find it even though I know I've seen it before.

    What bell are we talking about peter? Since a K is 1024 how would I know that 32k is $7fff. This memory stuff is really frying my brain, I just can't get a handle on it. I have no problem with hex but the memory stuff ouch.

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    ·······

    ······· "What do you mean, it doesn't have any tubes?"
    ······· "No such thing as a dumb question" unless it's on the internet


    Post Edited (mosquito56) : 6/11/2009 5:49:56 AM GMT
  • nohabnohab Posts: 96
    edited 2009-06-11 14:28
    32*1024=32768 in decimal, which is 8000 in hex. Since memory address start at 0 the highest address in 32k would be one less than $8000, ie $7fff
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