DP83869HM: DP83869HM copper Ethernet port will not connect

Hi,

Register 0x05 indicates the Auto Negotiation Capabilities shared by Link Parnter. Above indicates all 0x00. Seems like Link-Parnter is not sending or have issue on the cable.


Can you connect two DP83869 and check ?

Regards,
Geet

Aha, I think I found the problem. I have the pairs connected backwards compared to the EVM. I have a different chip that also labeled the pairs with A,B,C and D, so I used that connection to the magnetics in the jack. It turns out the connection on the DP83869 is backwards.

I'll do some surgery on the board and see if that fixes the problem.

John S.

Good, you found the problem. Keep me posted incase you need further assistance.

Regards,
Geet

Hi Geet,

it turns out this was not the problem. Even though the EVM has the pair wired backwards, there is a note saying "Mirror Mode". So it actually is correct as long as the straps are set for mirror mode. So my connections are correct.

I was thinking maybe it had to do with auto-MDIX, so I hooked some scope probes up to the RJ45 transformer pins and it looks like the sequence of FLPs is what it should be. With no cable plugged in a I get FLPs on channel A then Channel B, then back to channel A etc. Just like other devices do. But when plugged into another device I don't see the alternating channel A/B, I get identical sequences of FLPs on both channels simultaneously. I have not seen this with anything else. I tried connecting to both a computer and switch and get the same results. So it is still not working.

At this time I'm not sure whether this is an auto-MDIX or auto-negotiation issue.

I just got in another board with the DP83869 (I'll talk about it in a different post) and its copper Ethernet connection works perfectly, I hooked the MDI connection up exactly the same on both boards so I'm not sure what is going on with this first board.

John S.

Hi John,

"But when plugged into another device I don't see the alternating channel A/B, I get identical sequences of FLPs on both channels simultaneously. I have not seen this with anything else. "

This may be as both DUT and Link-Partner both are transmitting the FLPs alternating on channel A and B.


When you say it's working on other Board ? This is EVM or your own board ??

Regards,
Geet

Yes, it certainly looks like both side are stepping on each others toes, BUT the auto-MDIX protocol is supposed to prevent that from happening. I looked at what happens with a bunch of other devices that are both "PC" type and the auto-MDIX does in fact eventually figure things out. The DP83869 seems to be the only one I have tried that does not work.

The "other board" is my own board, I don't have an EVM. And IT does properly connect even when connected to a "PC" type link partner. So it looks like it is not something inherent in the DP83869.

Thanks,

John S.

Auto-MDIX is supported on DP83869. Do Link Partner Auto Negotiation register showing some non zero content ?

Can you try connecting in 100M mode ?


Regards,
Geet

Hi John,

Any further updates ? Are you able to make it working ?

Regards,
Geet

Hi Geet,
I've given up on this on my board for now. I'm going to try and get this working on the EVM, once I can get the MDIO working. Tomorrow I'm getting some Adafruit tinket M0 boards in which a very tiny ARM processor board with USB interface which make very nice MDIO controllers. So if I don't get the inf file to get the onboard MDIO working, I'll hook up one of the Adafruit boards so I can start looking at registers. The board I designed already has one of these on it for the DP83869. With this I can work on the EVM until it works thern check register differences and find out what is wrong with my board.

John S.

Hi John S,


This is the first time we tried integrating MCU on DP83869 EVM to make it easy for the customers as they don't have to purchase seperate MSP430 Launch Pad. We are looking in where it got broken as it was tested in our labs before release.

In the time being, a easier and more tested route can be : MDIO-USB tool with MSP430F5529 LaunchPad : It's been used by 100's of our customers w/o any issue for many years.

Once you have working solution, you may try enabling the Adrafruit or some other solution of your choice.

Regards,
Geet