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DS1307 Pullups — Parallax Forums

DS1307 Pullups

NewzedNewzed Posts: 2,503
edited 2007-09-30 17:00 in Propeller 1
I am trying to design a new module which uses Prop Pins 0-2 and 4-7.· One of the items on the module is a DS1307.· I normally take the SDA and SCL pullups to my 3.3VDC source.· Since Pin 3 is available, is there any reason I can not tie the two pullups to Pin 3 and just keep that pin high.· it would certainly tidy up the layout.

Sid

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Don't have VGA?
Newzed@aol.com
·

Comments

  • deSilvadeSilva Posts: 2,967
    edited 2007-09-30 12:48
    It is very uncommon, but of course possible - and don't forget the resistors in the first place smile.gif
  • NewzedNewzed Posts: 2,503
    edited 2007-09-30 14:13
    I know it is possible, but will it work?· The pullups are 10K and when the SDA and/or SCL pin goes low, max current thru the pullup pin would be about .33ma.

    Sid

    ▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
    Yesterday is history, tomorrow is a mystery, and today is a gift.

    That is why they call it the present.

    Don't have VGA?
    Newzed@aol.com
    ·
  • deSilvadeSilva Posts: 2,967
    edited 2007-09-30 17:00
    The max current for a Prop pin is 40 mA = x 1500.
    However 10k is just a conventional value used out of convenience. Any value between 3k3 and 33k should work, and some even say 1k to 100k. So just pick a higher value (47k?) and the current drain will be negligeable.

    Post Edited (deSilva) : 9/30/2007 5:14:13 PM GMT
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