Hi Roberto,
yes this is basically two diodes and one capa.
Take a look on Maxim datasheets of devices supporting parasite power, you
will see the internal parasite circuit.
increasing the capacitor may store more charge for convertT, however, this
also impact the rising duration of the DQ signal outside the specs.
there are also some circuit that make use of a ds2406 to control the
charging of the capacitor.
you may also find additional info here:
http://stomach.v2.nl/docs/Hardware/1-Wire/app147.pdf
Pascal
2011/2/6 Roberto Spadim <[email protected]>
> how is the parasite power work?
> for example...
> it get power from data, store in a internal capacitor/inductor/batery and
> use it
> could i change bus and put a external capacitor/inductor/batery
> getting power from data and supply my device? (increase internal
> capacity) for example:
>
> DATA ----------diode---->|----capacitor---------------> DS1820 POWER
> PIN
> GROUND --------------------------------|
>
> DATA ------------------------------> DS1820 DATA PIN
> GROUND ---------------------------> DS1820 GROUND PIN
>
> 2011/2/6 Pascal Baerten <[email protected]>:
> > hi,
> >
> > simultaneous could work in parasite power with limitations:
> >
> > 1)owfs has to issue strongpullup and lock the bus for duration of
> conversion
> > after receiving the convertT command, the unpowered sensor(s) pump the
> > current from the DQ line.
> > to give more current, the master has to put the DQ wire to vcc with a
> strong
> > pullup for the duration of the conversion
> > the duration is the max conversion time needed by the slowest sensor
> model
> > connected.
> >
> > 2) maximum of number of parasite powered sensors: 7 sensors.
> > given that
> > a ds18b20 use up to 1,5mA during convertT and scratchpad
> > a ds18b20 work down to 3V
> > the recommended 1wire vcc is 5V -> the acceptable voltage drop is 2V
> > a busmaster strongpullup has a ~180ohm to vcc
> > -> max current: 2v/180ohms == 11mA
> > max sensors "pumping" 1,5mA simultaneously on DQ= 11/1,5= 7 sensors.
> >
> > this is valid only with strongpull capables 1wire masters.
> > using a hub based on ds2409 will support only one parasite powered sensor
> > converting at a time.
> >
> >
> >
> >
> > Pascal
> >
> >
> >
> > 2011/2/6 Roberto Spadim <[email protected]>
> >>
> >> hummm nice =]
> >> try power them with 5v and check, i think it work :)
> >>
> >> 2011/2/5 patyrk <[email protected]>:
> >> > Dnia 2011-02-05, sob o godzinie 20:59 -0200, Roberto Spadim pisze:
> >> >> i don't know how alias work
> >> >> but you have a directory /uncached/xxxxxxxxxxxx/temperature and
> >> >> /xxxxxxxxxxxx/temperature
> >> >> you should use the cached version, not the uncached
> >> >
> >> > ok, that's right I'm using cached version, the alias could be
> misleading
> >> > so the commands look like this
> >> >
> >> > owread -s 2485 28.E4B5BF020000/temperature
> >> >
> >> >
> >> > But for Paul wrote, I understand that it won't work now in owfs if
> >> > sensors are parasite powered.
> >> >
> >> >
> >> > --
> >> > p4trykx
> >> >
> >> >
> >> >>
> >> >> 2011/2/5 patyrk <[email protected]>:
> >> >> > Dnia 2011-02-05, sob o godzinie 11:23 -0500, Paul Alfille pisze:
> >> >> >> Yes, you need the cache to store the time markers.
> >> >> >
> >> >> > To Roberto:
> >> >> > Does owread -s 2485 patryk/temperature use the cache?
> >> >> >
> >> >> >
> >> >> >> If simultaneous works in passive mode, I'll make the change.
> >> >> > I think with all parasite XOR powered it will work. But I'm not
> >> >> > certain
> >> >> > what happens with mixed configuration.
> >> >> > Specs says this
> >> >> > If the DS18B20 is powered by an
> >> >> > external supply, the master can issue read time slots after the
> >> >> > Convert
> >> >> > T command and the DS18B20 will
> >> >> > respond by transmitting a 0 while the temperature conversion is in
> >> >> > progress and a 1 when the conversion
> >> >> > is done. In parasite power mode this notification technique cannot
> be
> >> >> > used since the bus is pulled high by
> >> >> > the strong pullup during the conversion.
> >> >> >
> >> >> > Is this "read time slots" optional?
> >> >> >
> >> >> > --
> >> >> > P4trykx
> >> >> >
> >> >> >
> >> >> >
> >> >> >
> >> >> >
> >> >> >
> >> >> >
> >> >> >
> >> >> >>
> >> >> >> On Sat, Feb 5, 2011 at 10:54 AM, Roberto Spadim
> >> >> >> <[email protected]> wrote:
> >> >> >> > maybe it works with cached version, not uncached
> >> >> >> >
> >> >> >> > 2011/2/5 patyrk <[email protected]>:
> >> >> >> >> Hello
> >> >> >> >> Fist, sorry for double messages. My e-mail client went nuts.
> >> >> >> >>
> >> >> >> >> I previously said that simultaneous temp. conversion is not
> >> >> >> >> possible
> >> >> >> >> with parasite power. Well, I was wrong. This mail is to sum up
> >> >> >> >> all that
> >> >> >> >> wrote before.
> >> >> >> >>
> >> >> >> >> The specs of ds18b20 aren't very clear about it. However there
> is
> >> >> >> >> a
> >> >> >> >> command skip rom mentioned on page 11
> >> >> >> >>
> >> >> >> >> SKIP ROM [CCh]
> >> >> >> >> The master can use this command to address all devices on the
> bus
> >> >> >> >> simultaneously without sending out
> >> >> >> >> any ROM code information. For example, the master can make all
> >> >> >> >> DS18B20s
> >> >> >> >> on the bus perform
> >> >> >> >> simultaneous temperature conversions by issuing a Skip ROM
> >> >> >> >> command
> >> >> >> >> followed by a Convert T [44h]
> >> >> >> >> command.
> >> >> >> >>
> >> >> >> >> Moreover I asked about this simultaneous conversion on some
> >> >> >> >> Polish uC
> >> >> >> >> board and 2 users replied that they use this feature and it
> works
> >> >> >> >> even
> >> >> >> >> with parasite power. So I thinks it would be nice to have this
> >> >> >> >> feature
> >> >> >> >> working in owfs because its very useful with many ds1820.
> >> >> >> >>
> >> >> >> >> I've found some messages form 2006 and 2008 on this list that
> say
> >> >> >> >> simultaneous is working. But it seems not to work in my case. I
> >> >> >> >> use
> >> >> >> >> ds2480b master connected to serial port and few ds18b20 and 2
> >> >> >> >> ds18s20.
> >> >> >> >>
> >> >> >> >> Maybe I'm using it wrong. This is my script
> >> >> >> >> #!/bin/sh
> >> >> >> >> owwrite -s 2485 /simultaneous/temperature "1"
> >> >> >> >>
> >> >> >> >> temp="temperature"
> >> >> >> >> owread -s 2485 patryk/"$temp"
> >> >> >> >> owread -s 2485 pokoj/"$temp"
> >> >> >> >> owread -s 2485 pokoj_grzejnik/"$temp"
> >> >> >> >> owread -s 2485 korytarz/"$temp"
> >> >> >> >> owread -s 2485 korytarz_grzejnik/"$temp"
> >> >> >> >> owread -s 2485 tata/"$temp"
> >> >> >> >> owread -s 2485 dziadek/"$temp"
> >> >> >> >> owread -s 2485 zielony/"$temp"
> >> >> >> >>
> >> >> >> >> echo "koniec"
> >> >> >> >>
> >> >> >> >>
> >> >> >> >> It takes about 10 seconds no matter if I use simultaneous.
> >> >> >> >> owwrite takie about 0.02 seconds that's to short.
> >> >> >> >>
> >> >> >> >>
> >> >> >> >> --
> >> >> >> >> p4trykx
> >> >> >> >>
> >> >> >> >>
> >> >> >> >>
> >> >> >> >>
> >> >> >> >>
> >> >> >> >>
> >> >> >> >>
> ------------------------------------------------------------------------------
> >> >> >> >> The modern datacenter depends on network connectivity to access
> >> >> >> >> resources
> >> >> >> >> and provide services. The best practices for maximizing a
> >> >> >> >> physical server's
> >> >> >> >> connectivity to a physical network are well understood - see
> how
> >> >> >> >> these
> >> >> >> >> rules translate into the virtual world?
> >> >> >> >> http://p.sf.net/sfu/oracle-sfdevnlfb
> >> >> >> >> _______________________________________________
> >> >> >> >> Owfs-developers mailing list
> >> >> >> >> [email protected]
> >> >> >> >> https://lists.sourceforge.net/lists/listinfo/owfs-developers
> >> >> >> >>
> >> >> >> >>
> >> >> >> >
> >> >> >> >
> >> >> >> >
> >> >> >> > --
> >> >> >> > Roberto Spadim
> >> >> >> > Spadim Technology / SPAEmpresarial
> >> >> >> >
> >> >> >> >
> >> >> >> >
> ------------------------------------------------------------------------------
> >> >> >> > The modern datacenter depends on network connectivity to access
> >> >> >> > resources
> >> >> >> > and provide services. The best practices for maximizing a
> physical
> >> >> >> > server's
> >> >> >> > connectivity to a physical network are well understood - see how
> >> >> >> > these
> >> >> >> > rules translate into the virtual world?
> >> >> >> > http://p.sf.net/sfu/oracle-sfdevnlfb
> >> >> >> > _______________________________________________
> >> >> >> > Owfs-developers mailing list
> >> >> >> > [email protected]
> >> >> >> > https://lists.sourceforge.net/lists/listinfo/owfs-developers
> >> >> >> >
> >> >> >>
> >> >> >>
> >> >> >>
> ------------------------------------------------------------------------------
> >> >> >> The modern datacenter depends on network connectivity to access
> >> >> >> resources
> >> >> >> and provide services. The best practices for maximizing a physical
> >> >> >> server's
> >> >> >> connectivity to a physical network are well understood - see how
> >> >> >> these
> >> >> >> rules translate into the virtual world?
> >> >> >> http://p.sf.net/sfu/oracle-sfdevnlfb
> >> >> >> _______________________________________________
> >> >> >> Owfs-developers mailing list
> >> >> >> [email protected]
> >> >> >> https://lists.sourceforge.net/lists/listinfo/owfs-developers
> >> >> >
> >> >> >
> >> >> >
> >> >> >
> >> >> >
> ------------------------------------------------------------------------------
> >> >> > The modern datacenter depends on network connectivity to access
> >> >> > resources
> >> >> > and provide services. The best practices for maximizing a physical
> >> >> > server's
> >> >> > connectivity to a physical network are well understood - see how
> >> >> > these
> >> >> > rules translate into the virtual world?
> >> >> > http://p.sf.net/sfu/oracle-sfdevnlfb
> >> >> > _______________________________________________
> >> >> > Owfs-developers mailing list
> >> >> > [email protected]
> >> >> > https://lists.sourceforge.net/lists/listinfo/owfs-developers
> >> >> >
> >> >> >
> >> >>
> >> >>
> >> >>
> >> >
> >> >
> >> >
> >> >
> >> >
> ------------------------------------------------------------------------------
> >> > The modern datacenter depends on network connectivity to access
> >> > resources
> >> > and provide services. The best practices for maximizing a physical
> >> > server's
> >> > connectivity to a physical network are well understood - see how these
> >> > rules translate into the virtual world?
> >> > http://p.sf.net/sfu/oracle-sfdevnlfb
> >> > _______________________________________________
> >> > Owfs-developers mailing list
> >> > [email protected]
> >> > https://lists.sourceforge.net/lists/listinfo/owfs-developers
> >> >
> >> >
> >>
> >>
> >>
> >> --
> >> Roberto Spadim
> >> Spadim Technology / SPAEmpresarial
> >>
> >>
> >>
> ------------------------------------------------------------------------------
> >> The modern datacenter depends on network connectivity to access
> resources
> >> and provide services. The best practices for maximizing a physical
> >> server's
> >> connectivity to a physical network are well understood - see how these
> >> rules translate into the virtual world?
> >> http://p.sf.net/sfu/oracle-sfdevnlfb
> >> _______________________________________________
> >> Owfs-developers mailing list
> >> [email protected]
> >> https://lists.sourceforge.net/lists/listinfo/owfs-developers
> >
> >
> >
> > --
> > Pascal
> > www.brain4home.eu
> > to subscribe, send a mail to <[email protected]>
> >
> >
> ------------------------------------------------------------------------------
> > The modern datacenter depends on network connectivity to access resources
> > and provide services. The best practices for maximizing a physical
> server's
> > connectivity to a physical network are well understood - see how these
> > rules translate into the virtual world?
> > http://p.sf.net/sfu/oracle-sfdevnlfb
> > _______________________________________________
> > Owfs-developers mailing list
> > [email protected]
> > https://lists.sourceforge.net/lists/listinfo/owfs-developers
> >
> >
>
>
>
> --
> Roberto Spadim
> Spadim Technology / SPAEmpresarial
>
>
> ------------------------------------------------------------------------------
> The modern datacenter depends on network connectivity to access resources
> and provide services. The best practices for maximizing a physical server's
> connectivity to a physical network are well understood - see how these
> rules translate into the virtual world?
> http://p.sf.net/sfu/oracle-sfdevnlfb
> _______________________________________________
> Owfs-developers mailing list
> [email protected]
> https://lists.sourceforge.net/lists/listinfo/owfs-developers
>
--
Pascal
www.brain4home.eu
to subscribe, send a mail to <[email protected]>
------------------------------------------------------------------------------
The modern datacenter depends on network connectivity to access resources
and provide services. The best practices for maximizing a physical server's
connectivity to a physical network are well understood - see how these
rules translate into the virtual world?
http://p.sf.net/sfu/oracle-sfdevnlfb
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