Re: [Owfs-developers] Microchip acting as 1Wire

[<re...@du...>]

Hi,

 > I would like to ask if there are some experiences where the
 > Microchip's PICmicro=AE microcontroller devices (PICs) are programmed =
to
 > act (behave) as a 1-wire device (as DS2431, DS2433.... for example).


I've been experimenting on that, and although possible there are some=20
drawbacks.
As 1-wire master, anything is ok. the microchip creates the 'clock'=20
(within 1-wire specs) and reading data from the slave is easy.
However, to create a 1-wire slave, a microchip running at 4MHz=20
(1MHz/instruction) just isn't fast enough it seems. It can work, but=20
there are timing problems. The dallas 1-wire masters will create such=20
short pull-downs (1-2 us or so) that it is very hard for the slave to=20
detect. It may work, it may not, varying on conditions, cable length and=20
other factors, but i wasn't able to get it to work reliably. All other=20
stuff is pretty easy going, even like generating a serial id on first=20
time, or complying to the standard instruction set.
I feel that or you must pick a faster microchip, or some additional=20
electronics may be needed to improve the signal, which would in turn=20
quickly leads to using 2 i/o pins instead of one.
I am not really a elecrotechnician, more a programmer (although not=20
specialized in microchip), and at the time we could solve our problems=20
with standard-but-expensive dallas ic's.

regards,

rene


Petr Jakes wrote:
> Dear group,
>=20
> I think, according to the Maxim App Note 2420,
> http://www.maxim-ic.com/appnotes.cfm/appnote_number/2420
>=20
> such a solution can be used to control devices (motors etc.) over 1-wir=
e
> network.
>=20
> Petr Jakes
>=20
>=20
>=20
>=20
>=20
>=20
>=20
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