Am 30.04.2015 um 04:11 schrieb Loren Amelang:
> On Wednesday, April 29, 2015 at 3:35 PM,
> owfs-developers-requ...@lists.sourceforge.net wrote:
>
> From: Jan Kandziora <j...@gmx.de> Subject: Re: [Owfs-developers]
> Temperature sensitive bus timing using DS18B20 ... AS A SIDE NOTE,
> you have DISABLED the kernel's w1 drivers if you don't use them? If
> not, you'll get a conflict between the kernel driver and OWFS
> accessing the host adaptor at the same time, leading to exactly the
> scenario you've described (magically disappearing chips).
>
> Jan,
>
> Just checking... Since I've never been clear about the relationship
> of my default Ubuntu install of owfs to w1...
>
> Are you saying that even if we don't edit owfs.conf to explicitly
> enable w1: --- # ...and owserver uses the real hardware, by default
> fake devices # This part must be changed on real installation #
> server: FAKE = DS18S20,DS2405 # LA140622 commented # # USB device:
> DS9490 #server: usb = all server: w1 # LA140622 added --- It will
> still be active? Or is that "server: w1" setting the default when you
> build your own owfs, and it is only the Ubuntu version that doesn't
> include it? In my system nothing was happening on the bus until I
> added the w1 line.
>
The kernel has it's own onewire subsystem, made for accessing battery
and backlight controller chips on some notebooks. But it's a
full-featured system and it always *CLAIMS* all the onewire host
adaptors which are present in the system.
That's something which happens automatically and you can't configure by
editing owfs.conf. You have two choices to configure OWFS and the kernel
driver properly:
* Either you tell OWFS to use the kernel driver instead of directly
accessing the hardware. That's the --w1 option or "w1" owfs.conf option.
You cannot use --usb, --i2c and so on in this case and lose the
functionality of being able to distinguish chips by bus.
* Or you disable the kernel driver -- at least the host adaptor types
you want to use for OWFS -- by unloading/blacklisting the kernel driver
modules. And use --usb, --i2c, and so on instead of --w1.
> I'm also confused by your "kernel driver and OWFS accessing the host
> adaptor at the same time" line. Doesn't "host adaptor" imply USB or
> some other hardware beyond the simple hardware I/O line that w1
> accesses? Maybe w1 could be considered the conceptual equivalent of
> USB or some other host adaptor, like it appears in my owfs.conf, but
> accessing a totally different hardware bus? Or have I missed some
> basic concept here?
>
The onewire host adaptor chip is the DS2482 or DS2490 etc.
If both the kernel w1 driver and the OWFS --usb or --i2c driver are
accessing the host adaptor chip at the same time, garbage on the onewire
bus is the result, as the commands from to sources are mixed with each
other.
Kind regards
Jan
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