Ethernet without dock

Peter
 
Posts: 14
Joined: Sat Dec 06, 2014 6:00 am

Ethernet without dock

Fri Jan 16, 2015 8:46 am

Hi,

I tried to wire up ethernet directly without using RJ45 jacks.
I added 33nF cpacitors on all signal wires for this. (see TI application note www.ti.com/lit/an/snla088a/snla088a.pdf )
Unfortunately I still do not get a link.

Weird thing however is that the ethernet connection does work when I attach the dock but still connect ethernet directly from the Pins instead of using the RJ45 jack.

Peter

Greenwire-Elektronik
 
Posts: 101
Joined: Thu Dec 04, 2014 6:31 am

Re: Ethernet without dock

Fri Jan 16, 2015 11:46 am

Can you somehow make a picture of your wiring?
Buy now - breakout board for VoCore to easy adapting your idea!

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Pyrofer
 
Posts: 61
Joined: Tue Oct 21, 2014 11:35 am

Re: Ethernet without dock

Sun Jan 18, 2015 4:55 pm

How many times is this going to come up???

The 1.8v centertap is required for things to work. I would expect that the dock has the magnetics with the 1.8v connection and having it there is enough to make things work. If you don't want the dock use a MagJack with magnetics built in and connect the 1.8v pin.
If the RJ45 connector is annoying then get the magnetics on their own, but you do need them.

Peter
 
Posts: 14
Joined: Sat Dec 06, 2014 6:00 am

Re: Ethernet without dock

Mon Jan 26, 2015 2:00 am

Hi Pyofer,

thanks for the reply, but I could not solve the problem yet.

The issue is: I can not use a MagJack. I simply have no space, and as in the TI application note linked in my original post, there seems to be an option for a board-to-board connection. I actually got it running on a different ARM board. The PHY of the vocore seems to be more stringent though.

According to the application note I added 33nF cpacitors on all signal wires. The note says magnetics are not needed in this case for a short connection.
What would I need to do with the 1.8V you mentioned?

Thanks!

Regards

Peter

Pyrofer
 
Posts: 61
Joined: Tue Oct 21, 2014 11:35 am

Re: Ethernet without dock

Mon Jan 26, 2015 11:35 am

Well, I am not sure what you would do with the 1.8v in your situation. Can you put a link to the appnote here?

How "short" is short? What connections are you using?

The Ethernet magnetics come in some TINY smd components so it might be possible to squeeze them in without an actual RJ45, you can probably salvage some from an old router or switch but they are cheap to buy.

What is it you are connecting to? Do you have details on that device? I am interested in what you are trying to achieve now :)

Pyrofer
 
Posts: 61
Joined: Tue Oct 21, 2014 11:35 am

Re: Ethernet without dock

Mon Jan 26, 2015 11:41 am

Ok, just looked at your link from the other post. Did you connect the pull-up resistors and capacitor?

Did you get rx/tx the right way round (stupid question, but just in case!)?

Did you connect to 1.8v or 3.3v as shown in the appnote?

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