I haven't talked with Evgeniy recently, but did correspond extensively in
the past.
The W1 module polls the DS9490R at (I think) 1 second intervals to update
the temperature readings. Unfortunately it steals the entire 1-wire bus.
There were several solutions:
1. Remove DS9490R (rmmod ds9490r). You need to be root. If you are root,
libusb has some (non-portable) calls to remove a sensors and those are
already implemented in the owfs code. I think those calls failed in one
kernel version causing sudden grief.
2. Try to work with DS9490R. The current model (continuous polling) is not a
good fit with owfs. The number of 1-wire devices supported is small. And the
interface is truly ugly (sysfs anyone?) Evgeniy and I talked about
supporting a more general query on the w1 module. It would still be a little
awkward, send and receive a single byte sequence from a specified chip.
3. Evgeniy likes the netsys or (something like that) interface for talking
to w1. In fact I think that is his baby as well. I haven't taken the time to
learn it, yet.
4. In the past, owfs followed the datasheets in its communications. That
meant two calls if the process was to send an instruction, then read a
result. It is possible to make it all one process -- sending the
instruction, then 0xFFs and splitting the response to extract the result.
I've been adding a intervening layer to do this. This will allow the w1
module to be used in one-string mode. In fact this will be helpful for some
other adapters like the HA7Net web-scraping that have a large setup cost
and latency per packet.
So that is the status of the w1 interface. It's very linux-specific, and
even at best won't add any new function. I was more interested before we
managed to get I2C working, since there is a kernel module for that as well.
In short, just unload the ds9490r and everything will work. User-space
drivers are the way to go!
Paul Alfille
On 8/1/07, Jan Kandziora <[EMAIL PROTECTED]> wrote:
>
> Am Mittwoch, 1. August 2007 08:21 schrieb Matthias Urlichs:
> >
> > The simple solution is to blacklist the module (and/or unload it before
> > starting owserver) -- and ask your distro not to compile that module by
> > default. I have no idea if anybody uses it; it doesn't even support
> > hubs.
> >
> Well, from my point of view, the w1 kernel modules are in some kind of
> limbo,
> it hasn't changed much the last month.
>
> We discussed some minor items on this list a long time before with the w1
> author, Evgeniy Polyakov. Evgeniy is still active in linux kernel
> development, but his latest project was the distributed storage subsystem.
> I'm unsure if he has interest in w1 any more. If not, we could change the
> linux w1 subsystem so it doesn't interfere with owfs or make it an
> actually
> *useful* basic layer for owfs.
>
> Paul, could you ask him about that? From our last discussion, I had the
> impression I can't find the right words to talk to him.
>
> Kind regards
>
> Jan Kandziora
> --
> "And the next time you consider complaining that running Lucid Emacs
> 19.05 via NFS from a remote Linux machine in Paraguay doesn't seem to
> get the background colors right, you'll know who to thank."
> -- Matt Welsh
>
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