OWFS opens the i2c bus as a character device (like serial) and does all
communication over that. Each line is then handled independently.
So I agree with Jan, the electrical properties of the switch would be the
first place to look.
As for how to test, try a single DS2483, first directly connected, then on
one of the switch lines.
Paul
On Mon, Jul 22, 2013 at 11:35 AM, Jan Kandziora <[email protected]> wrote:
> Am 22.07.2013 10:49, schrieb Robert Budde:
> >
> > So my question:
> >
> > - What to look for? I2C or Onewire?
> >
> I'd look for I²C first. Hook up a scope and check if the rising signal
> edges are edgy enough. I²C is picky about that. The transmission gates
> in the PCA954x may round the edges additionally. Which pullup resistors
> do you use? On the branch lines, too?
>
> Do you use the TDFN package of the DS2483? If yes, make sure to connect
> the pad to GND.
>
>
> > - The PCA954x should be transparent to the owfs-driver. Is there
> > are way to check for hickups? Is the owfs-driver strictly using the
> > i2c-kernel-api (just making sure there is no exception from that)?
> >
> As the error is hardware-related, I would check this with a logic tester
> after doing the scope check for signal edges.
>
>
>
> > - Is somebody successfully using this or a similar setup?
> >
> Well, no. But why do you use a I²C switch? The DS2482-800 has eight
> onewire outputs and is widely tested, should you really want a star
> topology. (I would go for a lobe topology instead in nearly all cases,
> as cable length is not the big problem with Onewire.)
>
>
> Kind regards
>
> Jan
>
>
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