VoCore Ethernet with only capacitors
Posted: Sat May 23, 2015 4:45 pm
If you are like me and are a bit cheap / don't have any magnetics in the electronics lab and want ethernet right now. Then you can connect the ethernet with some capacitors you have laying around. Any capacitor from about 33nF to 0.1uF will be fine for this. 33nF is recommended.
It works just like using magnetics and is a perfect solution if you have networked devices on one pcb, I actually think this should have been made on the original board design so we could just connect the ethernet cable direct to the vocore without needing external magnetics, It is a recognized way to do ethernet without magnetics and I got this idea from reading a TI spec on how to use capacitors instead of magnetics (link below). This is a pretty clean solution if you just want to use something you have in your component box.
Page 5 of this shows the same schematic of what my changes are. VoCore already has the resistors, except they only go to ground and we need to pull them up to 3.3v and then add the capacitors.Connecting 2 vocore you only need one set of capacitors.
http://www.ti.com/lit/an/snla088a/snla088a.pdf
EDIT: use 33nF caps, not 0.1uF.
EDIT: Added picture of how I soldered it. I did this with a standard tip cheap ass soldering iron. So no excuses folks. The white stuff is "white out" to stiffen the wire, since its a single strand from a stranded cable.
It works just like using magnetics and is a perfect solution if you have networked devices on one pcb, I actually think this should have been made on the original board design so we could just connect the ethernet cable direct to the vocore without needing external magnetics, It is a recognized way to do ethernet without magnetics and I got this idea from reading a TI spec on how to use capacitors instead of magnetics (link below). This is a pretty clean solution if you just want to use something you have in your component box.
Page 5 of this shows the same schematic of what my changes are. VoCore already has the resistors, except they only go to ground and we need to pull them up to 3.3v and then add the capacitors.Connecting 2 vocore you only need one set of capacitors.
http://www.ti.com/lit/an/snla088a/snla088a.pdf
EDIT: use 33nF caps, not 0.1uF.
EDIT: Added picture of how I soldered it. I did this with a standard tip cheap ass soldering iron. So no excuses folks. The white stuff is "white out" to stiffen the wire, since its a single strand from a stranded cable.