Hi!
Can DP83849I be set up to work as an ethernet extender in simplex mode? If so, how?
I managed to set it up as a standard 4-wire ethernet extender in duplex mode but unsuccessful in setting up in simplex. I was playing with AN_EN, AN1 and AN0 jumpers on both ports but no luck.
Cheers.
Kris
Hi Kris,
I see that you have posted an edit to your question in another thread: 
For continuity, I will reply here. If you want to use only single pair cable (two wires) to connect all end points then you will only be able to achieve communication in one direction i.e. one port of the extender will be receive only and the other will be transmit only. This is a unique use case because ethernet PHYs will not establish a link if they do not receive idle pulses from link partner. So when a single pair cable is used on the transmit only port, the receive pins will not received any idles and link will not be established. DP83849I can be forced to establish a 100Mbps link but verify that the end point link partners that you are using can also support such modes.
In order to do this, you will need to strap the PHY to work in forced 100Mbps extender mode as per the app note linked in the previous reply. In this mode, auto-negotiation will be disabled and the device will only link up at 100Mbps speed.
Next you will need to disable Auto-MDIX via straps on pin no 2 and 60 of the device. This will put the PHY in forced MDI mode.
Next, you can use the Force 100Mbps link to be good by writing to register 0x16bit[5].
Lastly, you will need to construct your cable in such a way that transmitters on one side of the cable are connected to receivers on the other side. Since Auto-MDIX feature is turned off the PHYs this will not be happen automatically.
Note that this is not the usual use case for cable extender mode and has not been verified. Please test this out on your setup to make sure that it meets your requirements.
-Regards
Aniruddha
