POE - Power Over Ethernet
Started by ●November 2, 2004
I'm looking into developing a product for classroom monitoring that
would communicate over ethernet and be powered by 802.3af
compliant "Power Over Ethernet". Since I'm not trying to reinvent the
wheel, I'm looking for a cheap microprocessor solution like the
Rabbit modules where I can get the ethernet and web server aspect pre-
built. The Rabbit looks better than some of the others as it looks
like I can get at the center-taps of the ethernet magnetics and also
at the spare pairs on the ethernet jack.
My question is: Is anybody out there already doing POE with a Rabbit?
I did a search on the archives and came up empty.
Reply by ●November 2, 20042004-11-02
--- In rabbit-semi@rabb..., "Larry Siedentop" <larry@t...>
wrote:
>
> I'm looking into developing a product for classroom monitoring
that
> would communicate over ethernet and be powered by 802.3af
> compliant "Power Over Ethernet".
I don't know if others have looked at this, but we have at least
thought about it.
In the 32xx series modules the integrated magnetics would not allow
it, but the ethernet connections do run to the connectors, so you
could put your own magnetics and ethernet connections on a carrier
PCB.
In the 37xx modules, you could rework the module to make the power
connection.
One problem we found and maybe we didn't look hard enough, is that
other infrastructure that supports power over ethernet is in the
industrial realm. And that means more expense for things like hubs.
We specialize in custom carrier PCBs for many of these modules, so
let me know if we can help.
Reply by ●November 2, 20042004-11-02
Bruce --
powerDsine (powerdsine.com) provides injectors to provide the PoE
power. Also TI has a chip to pull down and down-convert the power
into something reasonable , like 5 volts. (see www.ti.com/poe )
They make boards for switch manufactureres, and also stand alone
equipment that sits beetween network switch and the the nodes.
You can use the spare wires 4,5 and 7,8 for power if you don't want
to install chokes to tap-off the power from the tx/rx lines.
TI has a nice webcast tutorial explaining how things work.
You'll need an ethernet connector with wires for all the pins.
PoE will be coming to a office desk near you as Voice-over-ip
rolls out in the next few years. I'm sure major network switch
manufacterrs will be adding PoE to their product line. HTH,
*the other brian On Tue, 2 Nov 2004, basicnode wrote:
>
> --- In rabbit-semi@rabb..., "Larry Siedentop" <larry@t...>
> wrote:
> >
> > I'm looking into developing a product for classroom monitoring
> that
> > would communicate over ethernet and be powered by 802.3af
> > compliant "Power Over Ethernet".
>
> I don't know if others have looked at this, but we have at least
> thought about it.
>
> In the 32xx series modules the integrated magnetics would not allow
> it, but the ethernet connections do run to the connectors, so you
> could put your own magnetics and ethernet connections on a carrier
> PCB.
>
> In the 37xx modules, you could rework the module to make the power
> connection.
>
> One problem we found and maybe we didn't look hard enough, is that
> other infrastructure that supports power over ethernet is in the
> industrial realm. And that means more expense for things like hubs.
>
> We specialize in custom carrier PCBs for many of these modules, so
> let me know if we can help.
>
---------------------------------
brian witt Railroads, computers, sailboats, etc. bwitt@bwit...
powerDsine (powerdsine.com) provides injectors to provide the PoE
power. Also TI has a chip to pull down and down-convert the power
into something reasonable , like 5 volts. (see www.ti.com/poe )
They make boards for switch manufactureres, and also stand alone
equipment that sits beetween network switch and the the nodes.
You can use the spare wires 4,5 and 7,8 for power if you don't want
to install chokes to tap-off the power from the tx/rx lines.
TI has a nice webcast tutorial explaining how things work.
You'll need an ethernet connector with wires for all the pins.
PoE will be coming to a office desk near you as Voice-over-ip
rolls out in the next few years. I'm sure major network switch
manufacterrs will be adding PoE to their product line. HTH,
*the other brian On Tue, 2 Nov 2004, basicnode wrote:
>
> --- In rabbit-semi@rabb..., "Larry Siedentop" <larry@t...>
> wrote:
> >
> > I'm looking into developing a product for classroom monitoring
> that
> > would communicate over ethernet and be powered by 802.3af
> > compliant "Power Over Ethernet".
>
> I don't know if others have looked at this, but we have at least
> thought about it.
>
> In the 32xx series modules the integrated magnetics would not allow
> it, but the ethernet connections do run to the connectors, so you
> could put your own magnetics and ethernet connections on a carrier
> PCB.
>
> In the 37xx modules, you could rework the module to make the power
> connection.
>
> One problem we found and maybe we didn't look hard enough, is that
> other infrastructure that supports power over ethernet is in the
> industrial realm. And that means more expense for things like hubs.
>
> We specialize in custom carrier PCBs for many of these modules, so
> let me know if we can help.
>
---------------------------------
brian witt Railroads, computers, sailboats, etc. bwitt@bwit...
Reply by ●November 2, 20042004-11-02
Thanks, I've checked it out already. For those interested, the site
is
http://focus.ti.com/analog/docs/articles.tsp?
familyIdd&templateId=2&path=templatedata/cm/brc/data/200309_poe_tabl
e_ad&articleType=brc&DCMP=KNC-poe
The video is well worth watching to bring you up to speed.
What I'm trying to do is create an interface that is IEEE 802.3af
compliant, which means it's got to work if the power comes over the
spare pairs or over the data pairs. The specs of the 3700 module look
like I can get at the centertap of the magnetics, which is what I
need for the power over data pairs way to work. --- In rabbit-semi@rabb..., Brian Witt <bwitt@v...> wrote:
> Bruce --
>
> powerDsine (powerdsine.com) provides injectors to provide the PoE
> power. Also TI has a chip to pull down and down-convert the power
> into something reasonable , like 5 volts. (see www.ti.com/poe )
> They make boards for switch manufactureres, and also stand alone
> equipment that sits beetween network switch and the the nodes.
>
> You can use the spare wires 4,5 and 7,8 for power if you don't want
> to install chokes to tap-off the power from the tx/rx lines.
> TI has a nice webcast tutorial explaining how things work.
> You'll need an ethernet connector with wires for all the pins.
>
> PoE will be coming to a office desk near you as Voice-over-ip
> rolls out in the next few years. I'm sure major network switch
> manufacterrs will be adding PoE to their product line. > HTH,
> *the other brian > On Tue, 2 Nov 2004, basicnode wrote:
> >
> > --- In rabbit-semi@rabb..., "Larry Siedentop"
<larry@t...>
> > wrote:
> > >
> > > I'm looking into developing a product for classroom monitoring
> > that
> > > would communicate over ethernet and be powered by 802.3af
> > > compliant "Power Over Ethernet".
> >
> > I don't know if others have looked at this, but we have at least
> > thought about it.
> >
> > In the 32xx series modules the integrated magnetics would not
allow
> > it, but the ethernet connections do run to the connectors, so you
> > could put your own magnetics and ethernet connections on a
carrier
> > PCB.
> >
> > In the 37xx modules, you could rework the module to make the
power
> > connection.
> >
> > One problem we found and maybe we didn't look hard enough, is
that
> > other infrastructure that supports power over ethernet is in the
> > industrial realm. And that means more expense for things like
hubs.
> >
> > We specialize in custom carrier PCBs for many of these modules,
so
> > let me know if we can help.
> > --------------------------------
-
> brian witt Railroads, computers, sailboats, etc. bwitt@v...
Reply by ●November 2, 20042004-11-02
On Nov 2, 2004, at 2:24 PM, Larry Siedentop wrote:
> What I'm trying to do is create an interface that is IEEE 802.3af
> compliant, which means it's got to work if the power comes over the
> spare pairs or over the data pairs. The specs of the 3700 module look
> like I can get at the centertap of the magnetics, which is what I
> need for the power over data pairs way to work.
You might want to look at using the RCM3400 instead, and then you have
more control over the Ethernet connector and magnetics.
It shouldn't be too difficult to take the reference design that adds
Ethernet to the RCM3400 and add the appropriate PoE circuitry and
voltage regulator to provide a stable 3.3V power source. I think that
would be much easier than trying to hack the RCM3700's Ethernet
connector.
--
Tom Collins - tom@tom@...
Rabbit Software Developer/Consultant based in Napa, California
Info on the Sniffter hand-held Network Tester: http://sniffter.com/
> What I'm trying to do is create an interface that is IEEE 802.3af
> compliant, which means it's got to work if the power comes over the
> spare pairs or over the data pairs. The specs of the 3700 module look
> like I can get at the centertap of the magnetics, which is what I
> need for the power over data pairs way to work.
You might want to look at using the RCM3400 instead, and then you have
more control over the Ethernet connector and magnetics.
It shouldn't be too difficult to take the reference design that adds
Ethernet to the RCM3400 and add the appropriate PoE circuitry and
voltage regulator to provide a stable 3.3V power source. I think that
would be much easier than trying to hack the RCM3700's Ethernet
connector.
--
Tom Collins - tom@tom@...
Rabbit Software Developer/Consultant based in Napa, California
Info on the Sniffter hand-held Network Tester: http://sniffter.com/
