Trouble making networking work with National Semiconductor DP83848J PHY

Hi David

I use DP83848K. I didn't compare the datasheets but I think they are basically the same device, J being the commercial grade and K the industrial.

My configuration is the following one:

- sopc system with Nios and 2 opercores MACs

- each MAC connects to a DP83484 PHY

- MAC has MII; PHY is connected in RMII mode; so I use a MII/RMII converter

- Micrium OS with InterNiche stack

- TCP/IP on one Ethernet port; tx/rx raw frames on the second one.

I haven't had problems in operating the phy and it worked immediately on my prototype board. I initially had a problem similar to yours (i.e could transmit on wire but not receive) but it actually was a problem with fpga hardware and HAL drivers: the interrupt line from MAC was not connected.

I'd suggest you probe the MII receive lines: if you can see data when the rx packet is being received, then the problem is not with the phy itself but in the way it has been connected to the MAC. You can debug the MAC registers and MAC driver and search for any generated rx error

Regards