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.
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
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]
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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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/
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]