On Tue, 2005-04-12 at 09:50 +0400, Serg Oskin wrote:
> "CM" == Christian Magnusson wrote:
>
> CM> On Mon, 2005-04-11 at 21:59, Serg Oskin wrote:
> >> In Mon, 11/04/2005 21:04 +0200, Christian Magnusson wrote:
> >>
> >> > I was thinking some more about simultaneous reading... How about adding
> >> > a feature like "echo 10 > simultaneous/temperature_frequency" which
> >> > automatically send a calculation restart after 10 seconds. That would
> >> > result into always fresh temperature values even if user doesn't
> >> > announce that he will read right now.
> >>
> >> Why not to do it by means of crond or the user's application?..
>
> CM> That's my point... It shouldn't be needed to have any second application
> CM> running to update the values frequently.
>
> After somebody will want to receive simultaneous/temperature_starttime and
> simultaneous/temperature_stoptime so gradually in OWFS there will be the
> crond... :) I do not see sense to complicate OWFS by duplicating functions
> of other programs which are available in any Unix.
>
> BTW, on shell it is done within the limits of one program:
>
> ------------------------8<-----------------------------
> #!/bin/sh
>
> mycrond() {
> while : ; do
> if [ -f $OneWire/simultaneous/temperature ]; then
> echo 1 >$OneWire/simultaneous/temperature
> fi
> sleep 10
> done
> }
>
> mycrond &
> ...
> ...
> ------------------------8<------------------------------
>
Sure... It's an easy way to solve it, but when you are running things
on embedded systems you have to save your ram wherever you can.
Just starting /bin/sh will consume 484Kb on your WRT54G router... and
that's a lot when you only have a few Mb free space.
Adding such a feature to owfs will increase code-size with max 300bytes
I guess and ram-usage will probably just be a couple of Kb even if you
start a new thread which handles it. No additional dynamic library is
loaded since everything is already there from owfs or owserver.
I don't think it's very important to add it, but it could make things
easier in some cases.
How about people using iButtons as identification cards etc... There
are key-rings to attach the iButton and then it's just to hold up
the button to the reader. This requires a loop searching for new
devices all the time, and then when a device is found, read the
memory or content and eventually accept the user's iButton.
This directory search could also be a low-level function in owserver
where it's searching for new devices as often as possible.
It wouldn't be very a very good user experience when you have to hold
your iButton to the reader for several seconds before it's detected and
accepted.
Just a few thoughts... :)
--
Christian Magnusson <[EMAIL PROTECTED]>
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