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Strong Pull Up for Parasitic Power mode on 1-Wire Devices — Parallax Forums

Strong Pull Up for Parasitic Power mode on 1-Wire Devices

ArchiverArchiver Posts: 46,084
edited 2002-02-10 00:13 in General Discussion
I just recieved my new I-Button DS1920 temperature chip and am
starting to experiment. Data sheets suggest a strong pull up on the
data pin during temp conversion. It must source 1mA. Since the stamp
pins can source up to 20mA could one use the data pin from the stamp
to power the DA1920 I-Button when it is in temperture conversion? I
could output it high for .5 sec while the conversion is taking
place. Or do I need to use a Mosfet like the data sheets suggest.

Comments

  • ArchiverArchiver Posts: 46,084
    edited 2002-02-08 02:55
    In a message dated 2/7/02 7:02:37 PM Central Standard Time,
    coondog45@h... writes:


    > I just recieved my new I-Button DS1920 temperature chip and am
    > starting to experiment. Data sheets suggest a strong pull up on the
    > data pin during temp conversion. It must source 1mA. Since the stamp
    > pins can source up to 20mA could one use the data pin from the stamp
    > to power the DA1920 I-Button when it is in temperture conversion? I
    > could output it high for .5 sec while the conversion is taking
    > place. Or do I need to use a Mosfet like the data sheets suggest.
    >

    There's a lot of code on the Parallax web site the demonstrates this. You
    simply need make the 1-Wire pin HIGH during the conversion. The next OW
    command will make the pin an input again. You might consider adding a series
    resistor (220 ohm) just to protect the Stamp from accidents.

    -- Jon Williams
    -- Parallax


    [noparse][[/noparse]Non-text portions of this message have been removed]
  • ArchiverArchiver Posts: 46,084
    edited 2002-02-08 16:03
    These are really well thought out devices. What are you building with it?
    Chris
    Original Message
    From: longbow42 [noparse]/noparse]mailto:[url=http://forums.parallaxinc.com/group/basicstamps/post?postID=SejdkUnoz8jMX4oMfjBuThQQ1YoitmUaVViNC57njGEcXLQPph7qp310fXLd9rgy8FRFl9U0U2chXg]coondog45@h...[/url
    Sent: Thursday, February 07, 2002 4:53 PM
    To: basicstamps@yahoogroups.com
    Subject: [noparse][[/noparse]basicstamps] Strong Pull Up for Parasitic Power mode on 1-Wire
    Devices


    I just recieved my new I-Button DS1920 temperature chip and am
    starting to experiment. Data sheets suggest a strong pull up on the
    data pin during temp conversion. It must source 1mA. Since the stamp
    pins can source up to 20mA could one use the data pin from the stamp
    to power the DA1920 I-Button when it is in temperture conversion? I
    could output it high for .5 sec while the conversion is taking
    place. Or do I need to use a Mosfet like the data sheets suggest.


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  • ArchiverArchiver Posts: 46,084
    edited 2002-02-09 23:56
    Thanks for your input. I am just tinkering with different devices and
    am attempting to make clocks, thermometers, accelerometers, etc for
    my recumbent bycicle. It has a strong 6 volt lead acid battery for
    the headlight system and I thought I'd take advantage of that large
    current source. Although I can buy commercial products for a fraction
    of the cost that I will spend, it is more fun to home brew.
    GPS might be next. LOL

    --- In basicstamps@y..., "Chris Loiacono \(E-mail\)" <chris01@t...>
    wrote:
    > These are really well thought out devices. What are you building
    with it?
    > Chris
    >
    >
    Original Message
    > From: longbow42 [noparse][[/noparse]mailto:coondog45@h...]
    > Sent: Thursday, February 07, 2002 4:53 PM
    > To: basicstamps@y...
    > Subject: [noparse][[/noparse]basicstamps] Strong Pull Up for Parasitic Power mode on 1-
    Wire
    > Devices
    >
    >
    > I just recieved my new I-Button DS1920 temperature chip and am
    > starting to experiment. Data sheets suggest a strong pull up on the
    > data pin during temp conversion. It must source 1mA. Since the stamp
    > pins can source up to 20mA could one use the data pin from the stamp
    > to power the DA1920 I-Button when it is in temperture conversion? I
    > could output it high for .5 sec while the conversion is taking
    > place. Or do I need to use a Mosfet like the data sheets suggest.
    >
    >
    > To UNSUBSCRIBE, just send mail to:
    > basicstamps-unsubscribe@y...
    > from the same email address that you subscribed. Text in the
    Subject and
    > Body of the message will be ignored.
    >
    >
    > Your use of Yahoo! Groups is subject to
    http://docs.yahoo.com/info/terms/
  • ArchiverArchiver Posts: 46,084
    edited 2002-02-10 00:13
    If you're interested in connecting a GPS receiver to your BS2p, be sure to
    checkout my article "Where In The World Is My BASIC Stamp?" in the March
    issue of Nuts & Volts magazine.

    -- Jon Williams
    -- Parallax


    In a message dated 2/9/02 5:57:46 PM Central Standard Time,
    coondog45@h... writes:


    > Thanks for your input. I am just tinkering with different devices and
    > am attempting to make clocks, thermometers, accelerometers, etc for
    > my recumbent bycicle. It has a strong 6 volt lead acid battery for
    > the headlight system and I thought I'd take advantage of that large
    > current source. Although I can buy commercial products for a fraction
    > of the cost that I will spend, it is more fun to home brew.
    >




    [noparse][[/noparse]Non-text portions of this message have been removed]
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