DP83848J Connects at 10mbps and not 100mbps

Doug Richard

Other Parts Discussed in Thread: DP83848J

Hi folks. I am using the DP83848J in a project. I am able to communicate at 10mbps (UDP, TCP, DHCP). However I am not able to make a connection at 100mbps. I have connected my project directly to my PC and am able to establish a link at 100 but that is all. My board is set up for auto-negotiation.

I have heard a lot of talk about the position of the 49.9 ohm resistors needing to be as close to the DP83848J as possible. Mine are a little over a 1/4 of an inch away. Is this to far away?

Again when I hook my device to a 10mbps switch my applicaiton works. When I try to connect to anything faster my project does not work. Any help would be appreciated.

Doug

over 11 years ago

0 Patrick OFarrell over 11 years ago

TI__Mastermind 31600 points

Doug,

Having the terminations 1/4 of an inch from the device should not be a problem, in and of itself. Do you have the ability to read and write the DP83848 registers via the MDC/MDIO interface?

Patrick

0 Doug Richard over 11 years ago in reply to Patrick OFarrell

Prodigy 30 points

Thanks Patrick. I should be able to read registers from the DP83848. Any particular registers you want me to check?

Doug

0 Doug Richard over 11 years ago in reply to Doug Richard

Prodigy 30 points

Able to get the system up and running this morning. The application was originally written for a different PHYTER chip. One of the things it does at the beginning is look for the different PHYTER chips OUI. Being it won't find it it never properly initializes. Solution was to have it check for the DP83848's OUI. Came right up.

Thanks for your help Patrick. Snooping around the DP83848 registers got us to this point.

Yours,

Doug

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DP83848J Connects at 10mbps and not 100mbps