> -----Original Message-----
> From: piclist-bounces@mit.edu [mailto:piclist-bounces@mit.edu] On Behalf
> Of Ruben J=F6nsson
> Sent: 03 March 2011 18:27
> To: Microcontroller discussion list - Public.
> Subject: Re: [PIC] 1 wire parasite mode
>=20
> >
> > On a one wire bus the so-called "strong pull-up" is only applied very
> > briefly prior to communicating with a peripheral.  It is not a resistiv=
e
> > pull-up as such, since nothing is expected to pull the bus low when it'=
s
> > applied.
> >
> > Regards
> >
> > Mike
> >
>=20
> No, it is applied when one or more parasitically powered 1-wire devices
> need to
> do a lengthy operation which consumes relatively much current (more than
> the
> pullup resistor can supply), like temperature measurement, voltage
> measurement
> or writing to eeprom.
>=20
> There is no need to apply a strong pullup for communication. There is an
> internal capacitor in each device that supplies power when the bus is low
> during communication.

I didn't say the strong pull-up was required for communication, or at least=
 I certainly didn't mean to imply that.  As you say, the strong pull-up is =
to power the device during operation, after which you can release the stron=
g pull-up and communicate with it to get the result.

Regards

Mike

=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D
This e-mail is intended for the person it is addressed to only. The
information contained in it may be confidential and/or protected by
law. If you are not the intended recipient of this message, you must
not make any use of this information, or copy or show it to any
person. Please contact us immediately to tell us that you have
received this e-mail, and return the original to us. Any use,
forwarding, printing or copying of this message is strictly prohibited.
No part of this message can be considered a request for goods or
services.
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D

--=20
http://www.piclist.com PIC/SX FAQ & list archive
View/change your membership options at
http://mailman.mit.edu/mailman/listinfo/piclist
.