W5100 Not Sending Link Pulses

Question

Hello, I am using the W5100 in a PCB design for a high profile project. I am currently able to write to the ethernet controller through SPI, but the link light on both the switch and the RJ-45 on my board are not lighting up. I have probed the trasnmitt output and have discovered that there are no link pulses being transmitted from the controller. There are link pulses that I am able to get on my board through the RJ-45 from the switch. I have 4 different boards and they all are acting the exact same way. Is there a chance that the front part of this chip is defective? Without any link pulses coming from the controller, it is impossible for both devices to auto negotiate and the link will not be made. Has this issue ever happened before, and if so how was it resolved? I used the schematic from the Arduino Ethernet boards. I have gone over the boards multiple times and cannot find a significant difference in the schematic. 770×690 91.1 KB 1073×677 98.1 KB

tamucobb · Answer

I actually made the changes to 50 ohms on my board and there is no link signal coming from the ethernet controller. Is there any other explanation for this? I have powered the chip and without the ethernet plugged into the RJ-45 there are no link pulses on the RX or TX line. There should be link pulses constantly sent from the controller in order to negotiate with another device. There is none coming from the controller. Could the controllers be defective?