rosbif
Posts: 42
Joined: Wed May 13, 2015 9:26 am

Direct connection Ethernet (no RJ45)

Mon Mar 14, 2016 2:01 pm

I'm working on a project where I'd like to eliminate the RJ45 connector and wire the ethernet cable directly to the Pi.
Has anyone done this successfully?

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rpdom
Posts: 12496
Joined: Sun May 06, 2012 5:17 am
Location: Essex, UK

Re: Direct connection Ethernet (no RJ45)

Mon Mar 14, 2016 2:08 pm

rosbif wrote:I'm working on a project where I'd like to eliminate the RJ45 connector and wire the ethernet cable directly to the Pi.
Has anyone done this successfully?
That would be very difficult. The ethernet connector isn't just a plain socket. It has some line transformers inside (it's known as a Magjack). Many network cards have the transformers in a separate package near the socket, but to save money and space the Pi uses one with that built in. The only way to wire directly would be to add external transformers.

(The first small batch of Pis was fitted with the wrong socket and they had to be removed and the correct ones put in to make the ethernet work).

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saper_2
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Location: PL

Re: Direct connection Ethernet (no RJ45)

Mon Mar 14, 2016 10:55 pm

HI,

As rpdom said, the RJ45 socket is integrated with LAN transformer. But if you really want to do it, then I'll tell you that you need a Ethernet transformer with 1CT:1CT ratio - I recently I committed a circuit (schematic so far) using LAN9514...

rosbif
Posts: 42
Joined: Wed May 13, 2015 9:26 am

Re: Direct connection Ethernet (no RJ45)

Tue Mar 15, 2016 5:34 pm

Found an easier way - I'm using a flat cat5 cable with low profile RJ45's - just fits inside the enclosure and bends upwards with about 5mm protruding from the socket on the Pi

Jabulon
Posts: 18
Joined: Sun Jan 14, 2018 10:45 am

Re: Direct connection Ethernet (no RJ45)

Mon Feb 19, 2018 4:23 am

saper_2 wrote:
Mon Mar 14, 2016 10:55 pm
HI,

As rpdom said, the RJ45 socket is integrated with LAN transformer. But if you really want to do it, then I'll tell you that you need a Ethernet transformer with 1CT:1CT ratio - I recently I committed a circuit (schematic so far) using LAN9514...
How do i connect these trasformers you recomended, just conect all 8 wires to each leg inbeween the striped down pi and the router's rj45?
I also found these but i belove there is a resistor and cap aray in the Pi ethernet conector trasformer.
https://uk.rs-online.com/mobile/p/lan-e ... s/5225917/

Where can i get a complete circuit like the one inside the Pi ethernet conector and how do i wire it on the Pi's PCB pins exactly pls?

I am planning to reduce the profile/height of the RPi3
and remove amongst other components the Ethernet
casing/connector too but i want to connect it to a
router via Ethernet. So i am going to solder wires
directly onto the Pi3 PCB Ethernet connections and
then wire them with very short wires (15cm) to a
router's LAN port RJ45 connections.
Chalenge: I read and saw pics about an embedded "magnetics isolator" circuit inside the Pi3 Ethernet connector.
Questions:
1. Do i need this for such a small wire distance?
2. If yes which one do i buy and how do i wire it?
3. Do i need all 8 Ethernet wires (don't need Gbps
speeds here)?
4. Any other hints about this type of wiring?

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Imperf3kt
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Location: Australia

Re: Direct connection Ethernet (no RJ45)

Mon Feb 19, 2018 4:58 am

Why not just reuse the ethernet jack you removed from the Pi?
Its fiddly to solder but not impossible (I managed to do it)
Stephen Hawking, rest in peace.
8 January 1942 – 14 March 2018

Jabulon
Posts: 18
Joined: Sun Jan 14, 2018 10:45 am

Re: Direct connection Ethernet (no RJ45)

Mon Feb 19, 2018 9:17 am

Imperf3kt wrote:
Mon Feb 19, 2018 4:58 am
Why not just reuse the ethernet jack you removed from the Pi?
Its fiddly to solder but not impossible (I managed to do it)
Becuse like is said i want to lower the profile, its too bulky. I might have left it put if i was to go with that...

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Imperf3kt
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Location: Australia

Re: Direct connection Ethernet (no RJ45)

Mon Feb 19, 2018 10:40 am

You can cut it up and make it smaller. Only the rear half of the ethernet port is actually needed, the rest is wires for physical connection and plastic.
Stephen Hawking, rest in peace.
8 January 1942 – 14 March 2018

Jabulon
Posts: 18
Joined: Sun Jan 14, 2018 10:45 am

Re: Direct connection Ethernet (no RJ45)

Mon Feb 19, 2018 10:11 pm

Imperf3kt wrote:
Mon Feb 19, 2018 10:40 am
You can cut it up and make it smaller. Only the rear half of the ethernet port is actually needed, the rest is wires for physical connection and plastic.
This is what i was thinking too it seems like the simplest solution...

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