DP83869HM: link up issue

Hi Amy,

Thank you for sending the schematics and register reads/writes. In your initial configuration I see that you did:

01DFH=0060H     // Enable MII to Copper

0000H=3100H     // Auto-negotiation enabled

0004H=01E1H     // Advertising 10/100M Speeds

0009H=0000H     // De-advertising 1000M Speeds

0010H=5048H     // 

001FH=4000H     // Soft Reset

I believe you already know this, but just to be sure Register 0x1DF is an extended register. More information about how to read and write these registers can be found here.

Did you set Register 0x18 = 0xE? This muxes LED_0 to RX_ER which is necessary for MII communication (LED_0 would need to be connected to the MAC as well).

Regards,

Alvaro

Hi Alvaro,

Yes, I already know that registers other than 0-31 are extension registers, the operation should be correct, because 1DFH after writing 0060H, The CLK for RX and TX measurements is clock output, which meets the requirements of MII.

RX_ER is connected to LED_1, so bit4-7 of register 18H is set to 0xE, but the link fails. The following figure shows some register content information that is printed on a periodic basis, and it is not possible to locate the problem at this time.

Regards,

Amy

Hi Amy,

It seems like your MII connections are okay, could you provide me with a block diagram of your set up? What is the Link-Partner?

The MAC Side connections, valid or not, should not affect the link status. The link status is dependent on the MDI Side (connector side). 

Regards,

Alvaro

Hi Alvaro,

Our goal is to achieve the ability to convert data between fiber/network ports. Using the DP83869EVM board, set the straps pins into the 100M or 1000M Media Convertor mode as per the EVM user guide. Verify that the feature works by pinging between the computers as shown in the following figure. Taking this scheme eliminates the need to write code. Could you please analyze whether this scheme is feasible?? Or is there a problem with the idea? 

PS: With this scheme, does the computer network port need to be set to enable forced 100M or 1000M, disable the self-negotiation function?

Regards,

Amy

Hi Amy,

Thank you for the block diagram. This is 100% possible with the DP83869EVM. An important note with Media Conversion is that Auto-negotiation will happen on the Copper side but NOT on the Fiber side.

For example:

We want to achieve 100M Media Conversion, so you configure the OPMODE straps to 101, 100Base-T to 100Base-FX.

In your diagram, the 869EVM and PC are connected via the copper cable, which means auto-negotiation will happen. The 869EVM will tell the PC that it is only able to operate at 100 Mbps and they'll link up.

This will not happen between the 869 and the Optical Fiber port. You will need to configure the Fiber port to operate at 100 Mbps.

Regards,

Alvaro