Would it be possible to share a memory device between two 1-wire busses?
Some sort of synchronisation would be required so that it wasn't swapped
while being read / written but that shouldn't be too difficult (PIO based
semaphore). You could even use two devices so that both busses have a device
that can be read / written at any time. It wouldn't provide real time access
but could be used to transfer the results of measurements made by the
microcontroller.
Just a thought.
Mark
On Jan 3, 2008 5:29 PM, Paul Alfille <[EMAIL PROTECTED]> wrote:
> On website at http://owfs.org/index.php?page=hydroelectric-plant (I've
> included my responses).
>
> ---------- Forwarded message ----------
> On Dec 13, 2007 3:44 PM, [EMAIL PROTECTED] <[EMAIL PROTECTED]> wrote:
>
> > I have an old and small hydroelectric powerplant
> > ( http://sundsvik.dnsalias.org/) run on a shoestring budget.
> > It is remotely monitored and controlled by a
> > system mainly based on 1-wire devices using OWFS.
> >
>
>
> > Thankyou for a very nice piece of software.
> > The 1-wire devices have their limitations, they
> > are for instance not very good at measuring
> > precise intervals and totals and other things.
> > Therefore I would like to design a flexible
> > device based on a microcotroller for instance a
> > PIC that can draw on the advantages of the 1-wire
> > protocol and extend the capabilities of the devices offered by Maxim.
> > The device to emulate that first comes to my mind
> > is the DS18S20 which has a rather simple
> > architecture with a read/write scratchpad memory
> > area which is ideal for my purposes.
> > My questions to you are:
> > 1) Commands 0xBE and 0x4E: Can I in any simple
> > way read and write whole or parts of the
> > scratchpad memory with OWFS? Is there a
> > one-to-one relationship between the reported
> > temperature and the content of the temperature registers?
> >
>
> Well, we read scratchpad internally, and it would be easy to make it
> externally visible.
> I don't currently, because it might overwhelm new users, and changing the
> scratchpad would make other aspects inaccurate (like temperature
> resolution).
>
> 2) Are you aware of any project for emulating the
> > Dallas 1-wire devices? I hate to reinvent the wheel.
> >
>
> Louis Swart's LCD uses a PIC to emulate a 1-wire device. Maxim in general
> is protective of the 1-wire device technology (for the slaves, the masters
> are fair game).
>
> A. Have you looked at the DS27xx chips? They have temperature, current,
> accumulators, timers, voltages, even a bit of memory. Pretty cheap. Look
> specifically at the DS2760 DS2751 DS2770 and DS2780
>
> B. There is no reason to blindly emulate the DS1820 -- we can create an
> entry to your chip using the command codes you like. It has to speak 1-wire
> (reset, selection, etc) but the actual protocol needn't be constrained.
>
> C. If you really want to be different, we can make a unique adapter and
> chips that don't have to talk true 1-wire between them. We can work to make
> it fall generally in the same scheme.
>
> D. There might be other resources (smart people) if you ask this question
> ion the owfs-developer's list.
>
> E. Although Dallas is phasing them out, the DS2404 has dual inputs --
> 1-wire and 3-wire and can serve as a bridge to the PIC.
>
>
> > Thanks in advance
> > Håkan Elmqvist
> >
>
>
> -------------------------------------------------------------------------
> This SF.net email is sponsored by: Microsoft
> Defy all challenges. Microsoft(R) Visual Studio 2005.
> http://clk.atdmt.com/MRT/go/vse0120000070mrt/direct/01/
> _______________________________________________
> Owfs-developers mailing list
> Owfs-developers@lists.sourceforge.net
> https://lists.sourceforge.net/lists/listinfo/owfs-developers
>
>
-------------------------------------------------------------------------
This SF.net email is sponsored by: Microsoft
Defy all challenges. Microsoft(R) Visual Studio 2005.
http://clk.atdmt.com/MRT/go/vse0120000070mrt/direct/01/
_______________________________________________
Owfs-developers mailing list
Owfs-developers@lists.sourceforge.net
https://lists.sourceforge.net/lists/listinfo/owfs-developers
