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5mhz cystal vs Xtal1 — Parallax Forums

5mhz cystal vs Xtal1

Oldbitcollector (Jeff)Oldbitcollector (Jeff) Posts: 8,091
edited 2007-04-16 05:10 in Propeller 1
I've ordered some EEPROMS from Microchip, so I'm gearing up to play with the idea of making my own memory cards/slot for my propeller setup. Since I'm using Protoboards, I'm not sure I can integrate that into the plan without modification of the board itself, so I'm thinking of building board #3 from the ground up on a breadboard. Looking at the Hydra specs, I see they used an XTAL1 vs the 5Mhz Crystal on the prop boards. Could someone share the advantages or disadvantages of this. Increases of speed, or loss of compatibility?

Thanks
Oldbit

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"Two things are infinite: the universe and human stupidity; and I'm not sure about the universe." -Albert Einstein

Comments

  • Mike GreenMike Green Posts: 23,101
    edited 2007-04-16 01:03
    The Hydra uses a 10MHz crystal instead of the 5MHz crystal used by the Demo Board and Protoboard. It uses PLL8 instead of PLL16 to get a resulting system clock of 80MHz just like all the other Propeller boards. There's no particular advantage or disadvantage to either. When Parallax put together a Propeller on a Stamp substrate for alpha testing, they used a 10MHz crystal because of the physically smaller size of the higher frequency crystal in a surface mount package. The Hydra's crystal is in a standard case that's the same size as the 5MHz crystal.
  • Oldbitcollector (Jeff)Oldbitcollector (Jeff) Posts: 8,091
    edited 2007-04-16 04:46
    Hmm... You've got me very tempted to just cut the power trace to the onboard epprom and install my own slot on my protoboard.

    Oldbitcollector

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    "Two things are infinite: the universe and human stupidity; and I'm not sure about the universe." -Albert Einstein
  • Mike GreenMike Green Posts: 23,101
    edited 2007-04-16 04:59
    Why cut the trace? You can add additional EEPROM to the Protoboard just by connecting it to pins 28 & 29 and setting the address select pins to something other than all zeros.
  • Oldbitcollector (Jeff)Oldbitcollector (Jeff) Posts: 8,091
    edited 2007-04-16 05:04
    Address select pins... Ok now you've lost me.. Where do I read? [noparse]:)[/noparse]


    <running for my propeller pdfs>

    Oldbitcollector

    ▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
    "Two things are infinite: the universe and human stupidity; and I'm not sure about the universe." -Albert Einstein
  • Paul BakerPaul Baker Posts: 6,351
    edited 2007-04-16 05:07
    The information Mike refered to is availible in the datasheet for the EEPROM.

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    Paul Baker
    Propeller Applications Engineer

    Parallax, Inc.
  • Oldbitcollector (Jeff)Oldbitcollector (Jeff) Posts: 8,091
    edited 2007-04-16 05:10
    THe only thing I hadn't gotten around to reading yet.... Thanks Paul


    Oldbitcollector

    ▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
    "Two things are infinite: the universe and human stupidity; and I'm not sure about the universe." -Albert Einstein
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